ruff: enable TC — flake8-type-checking (#11368)

## Problem

`TYPE_CHECKING` is used inconsistently across Python tests.

## Summary of changes
- Update `ruff`: 0.7.0 -> 0.11.2
- Enable TC (flake8-type-checking):
https://docs.astral.sh/ruff/rules/#flake8-type-checking-tc
- (auto)fix all new issues

poetry.lock

@@ -3111,30 +3111,30 @@ six = "*"
 
 [[package]]
 name = "ruff"
-version = "0.7.0"
+version = "0.11.2"
 description = "An extremely fast Python linter and code formatter, written in Rust."
 optional = false
 python-versions = ">=3.7"
 groups = ["dev"]
 files = [
-    {file = "ruff-0.7.0-py3-none-linux_armv6l.whl", hash = "sha256:0cdf20c2b6ff98e37df47b2b0bd3a34aaa155f59a11182c1303cce79be715628"},
+    {file = "ruff-0.11.2-py3-none-linux_armv6l.whl", hash = "sha256:c69e20ea49e973f3afec2c06376eb56045709f0212615c1adb0eda35e8a4e477"},
-    {file = "ruff-0.7.0-py3-none-macosx_10_12_x86_64.whl", hash = "sha256:496494d350c7fdeb36ca4ef1c9f21d80d182423718782222c29b3e72b3512737"},
+    {file = "ruff-0.11.2-py3-none-macosx_10_12_x86_64.whl", hash = "sha256:2c5424cc1c4eb1d8ecabe6d4f1b70470b4f24a0c0171356290b1953ad8f0e272"},
-    {file = "ruff-0.7.0-py3-none-macosx_11_0_arm64.whl", hash = "sha256:214b88498684e20b6b2b8852c01d50f0651f3cc6118dfa113b4def9f14faaf06"},
+    {file = "ruff-0.11.2-py3-none-macosx_11_0_arm64.whl", hash = "sha256:ecf20854cc73f42171eedb66f006a43d0a21bfb98a2523a809931cda569552d9"},
-    {file = "ruff-0.7.0-py3-none-manylinux_2_17_aarch64.manylinux2014_aarch64.whl", hash = "sha256:630fce3fefe9844e91ea5bbf7ceadab4f9981f42b704fae011bb8efcaf5d84be"},
+    {file = "ruff-0.11.2-py3-none-manylinux_2_17_aarch64.manylinux2014_aarch64.whl", hash = "sha256:0c543bf65d5d27240321604cee0633a70c6c25c9a2f2492efa9f6d4b8e4199bb"},
-    {file = "ruff-0.7.0-py3-none-manylinux_2_17_armv7l.manylinux2014_armv7l.whl", hash = "sha256:211d877674e9373d4bb0f1c80f97a0201c61bcd1e9d045b6e9726adc42c156aa"},
+    {file = "ruff-0.11.2-py3-none-manylinux_2_17_armv7l.manylinux2014_armv7l.whl", hash = "sha256:20967168cc21195db5830b9224be0e964cc9c8ecf3b5a9e3ce19876e8d3a96e3"},
-    {file = "ruff-0.7.0-py3-none-manylinux_2_17_i686.manylinux2014_i686.whl", hash = "sha256:194d6c46c98c73949a106425ed40a576f52291c12bc21399eb8f13a0f7073495"},
+    {file = "ruff-0.11.2-py3-none-manylinux_2_17_i686.manylinux2014_i686.whl", hash = "sha256:955a9ce63483999d9f0b8f0b4a3ad669e53484232853054cc8b9d51ab4c5de74"},
-    {file = "ruff-0.7.0-py3-none-manylinux_2_17_ppc64.manylinux2014_ppc64.whl", hash = "sha256:82c2579b82b9973a110fab281860403b397c08c403de92de19568f32f7178598"},
+    {file = "ruff-0.11.2-py3-none-manylinux_2_17_ppc64.manylinux2014_ppc64.whl", hash = "sha256:86b3a27c38b8fce73bcd262b0de32e9a6801b76d52cdb3ae4c914515f0cef608"},
-    {file = "ruff-0.7.0-py3-none-manylinux_2_17_ppc64le.manylinux2014_ppc64le.whl", hash = "sha256:9af971fe85dcd5eaed8f585ddbc6bdbe8c217fb8fcf510ea6bca5bdfff56040e"},
+    {file = "ruff-0.11.2-py3-none-manylinux_2_17_ppc64le.manylinux2014_ppc64le.whl", hash = "sha256:a3b66a03b248c9fcd9d64d445bafdf1589326bee6fc5c8e92d7562e58883e30f"},
-    {file = "ruff-0.7.0-py3-none-manylinux_2_17_s390x.manylinux2014_s390x.whl", hash = "sha256:b641c7f16939b7d24b7bfc0be4102c56562a18281f84f635604e8a6989948914"},
+    {file = "ruff-0.11.2-py3-none-manylinux_2_17_s390x.manylinux2014_s390x.whl", hash = "sha256:0397c2672db015be5aa3d4dac54c69aa012429097ff219392c018e21f5085147"},
-    {file = "ruff-0.7.0-py3-none-manylinux_2_17_x86_64.manylinux2014_x86_64.whl", hash = "sha256:d71672336e46b34e0c90a790afeac8a31954fd42872c1f6adaea1dff76fd44f9"},
+    {file = "ruff-0.11.2-py3-none-manylinux_2_17_x86_64.manylinux2014_x86_64.whl", hash = "sha256:869bcf3f9abf6457fbe39b5a37333aa4eecc52a3b99c98827ccc371a8e5b6f1b"},
-    {file = "ruff-0.7.0-py3-none-musllinux_1_2_aarch64.whl", hash = "sha256:ab7d98c7eed355166f367597e513a6c82408df4181a937628dbec79abb2a1fe4"},
+    {file = "ruff-0.11.2-py3-none-musllinux_1_2_aarch64.whl", hash = "sha256:2a2b50ca35457ba785cd8c93ebbe529467594087b527a08d487cf0ee7b3087e9"},
-    {file = "ruff-0.7.0-py3-none-musllinux_1_2_armv7l.whl", hash = "sha256:1eb54986f770f49edb14f71d33312d79e00e629a57387382200b1ef12d6a4ef9"},
+    {file = "ruff-0.11.2-py3-none-musllinux_1_2_armv7l.whl", hash = "sha256:7c69c74bf53ddcfbc22e6eb2f31211df7f65054bfc1f72288fc71e5f82db3eab"},
-    {file = "ruff-0.7.0-py3-none-musllinux_1_2_i686.whl", hash = "sha256:dc452ba6f2bb9cf8726a84aa877061a2462afe9ae0ea1d411c53d226661c601d"},
+    {file = "ruff-0.11.2-py3-none-musllinux_1_2_i686.whl", hash = "sha256:6e8fb75e14560f7cf53b15bbc55baf5ecbe373dd5f3aab96ff7aa7777edd7630"},
-    {file = "ruff-0.7.0-py3-none-musllinux_1_2_x86_64.whl", hash = "sha256:4b406c2dce5be9bad59f2de26139a86017a517e6bcd2688da515481c05a2cb11"},
+    {file = "ruff-0.11.2-py3-none-musllinux_1_2_x86_64.whl", hash = "sha256:842a472d7b4d6f5924e9297aa38149e5dcb1e628773b70e6387ae2c97a63c58f"},
-    {file = "ruff-0.7.0-py3-none-win32.whl", hash = "sha256:f6c968509f767776f524a8430426539587d5ec5c662f6addb6aa25bc2e8195ec"},
+    {file = "ruff-0.11.2-py3-none-win32.whl", hash = "sha256:aca01ccd0eb5eb7156b324cfaa088586f06a86d9e5314b0eb330cb48415097cc"},
-    {file = "ruff-0.7.0-py3-none-win_amd64.whl", hash = "sha256:ff4aabfbaaba880e85d394603b9e75d32b0693152e16fa659a3064a85df7fce2"},
+    {file = "ruff-0.11.2-py3-none-win_amd64.whl", hash = "sha256:3170150172a8f994136c0c66f494edf199a0bbea7a409f649e4bc8f4d7084080"},
-    {file = "ruff-0.7.0-py3-none-win_arm64.whl", hash = "sha256:10842f69c245e78d6adec7e1db0a7d9ddc2fff0621d730e61657b64fa36f207e"},
+    {file = "ruff-0.11.2-py3-none-win_arm64.whl", hash = "sha256:52933095158ff328f4c77af3d74f0379e34fd52f175144cefc1b192e7ccd32b4"},
-    {file = "ruff-0.7.0.tar.gz", hash = "sha256:47a86360cf62d9cd53ebfb0b5eb0e882193fc191c6d717e8bef4462bc3b9ea2b"},
+    {file = "ruff-0.11.2.tar.gz", hash = "sha256:ec47591497d5a1050175bdf4e1a4e6272cddff7da88a2ad595e1e326041d8d94"},
 ]
 
 [[package]]
@@ -3844,4 +3844,4 @@ cffi = ["cffi (>=1.11)"]
 [metadata]
 lock-version = "2.1"
 python-versions = "^3.11"
-content-hash = "715fc8c896dcfa1b15054deeddcdec557ef93af91b26e1c8e4688fe4dbef5296"
+content-hash = "fb50cb6b291169dce3188560cdb31a14af95647318f8f0f0d718131dbaf1817a"

pyproject.toml

@@ -53,7 +53,7 @@ jsonnet = "^0.21.0-rc2"
 
 [tool.poetry.group.dev.dependencies]
 mypy = "==1.13.0"
-ruff = "^0.7.0"
+ruff = "^0.11.2"
 
 [build-system]
 requires = ["poetry-core>=1.0.0"]
@@ -109,4 +109,5 @@ select = [
     "W", # pycodestyle
     "B", # bugbear
     "UP", # pyupgrade
+    "TC", # flake8-type-checking
 ]

scripts/download_basebackup.py

@@ -8,9 +8,12 @@
 from __future__ import annotations
 
 import argparse
+from typing import TYPE_CHECKING
 
 import psycopg2
-from psycopg2.extensions import connection as PgConnection
+
+if TYPE_CHECKING:
+    from psycopg2.extensions import connection as PgConnection
 
 
 def main(args: argparse.Namespace):

scripts/force_layer_download.py

@@ -7,13 +7,13 @@ import logging
 import signal
 import sys
 from collections import defaultdict
-from collections.abc import Awaitable
 from dataclasses import dataclass
 from typing import TYPE_CHECKING
 
 import aiohttp
 
 if TYPE_CHECKING:
+    from collections.abc import Awaitable
     from typing import Any
 
 

test_runner/cloud_regress/test_cloud_regress.py

@@ -4,11 +4,15 @@ Run the regression tests on the cloud instance of Neon
 
 from __future__ import annotations
 
-from pathlib import Path
+from typing import TYPE_CHECKING
 
 import pytest
-from fixtures.neon_fixtures import RemotePostgres
+
-from fixtures.pg_version import PgVersion
+if TYPE_CHECKING:
+    from pathlib import Path
+
+    from fixtures.neon_fixtures import RemotePostgres
+    from fixtures.pg_version import PgVersion
 
 
 @pytest.mark.timeout(7200)

test_runner/fixtures/auth_tokens.py

@@ -2,11 +2,12 @@ from __future__ import annotations
 
 from dataclasses import dataclass
 from enum import StrEnum
-from typing import Any
+from typing import TYPE_CHECKING, Any
 
 import jwt
 
-from fixtures.common_types import TenantId
+if TYPE_CHECKING:
+    from fixtures.common_types import TenantId
 
 
 @dataclass

test_runner/fixtures/benchmark_fixture.py

@@ -15,18 +15,20 @@ from typing import TYPE_CHECKING
 
 import allure
 import pytest
-from _pytest.config import Config
-from _pytest.config.argparsing import Parser
-from _pytest.fixtures import FixtureRequest
-from _pytest.terminal import TerminalReporter
 
-from fixtures.common_types import TenantId, TimelineId
 from fixtures.log_helper import log
-from fixtures.neon_fixtures import NeonPageserver
 
 if TYPE_CHECKING:
     from collections.abc import Callable, Iterator, Mapping
 
+    from _pytest.config import Config
+    from _pytest.config.argparsing import Parser
+    from _pytest.fixtures import FixtureRequest
+    from _pytest.terminal import TerminalReporter
+
+    from fixtures.common_types import TenantId, TimelineId
+    from fixtures.neon_fixtures import NeonPageserver
+
 
 """
 This file contains fixtures for micro-benchmarks.

test_runner/fixtures/compare_fixtures.py

@@ -11,7 +11,6 @@ from pathlib import Path
 from typing import TYPE_CHECKING, final
 
 import pytest
-from _pytest.fixtures import FixtureRequest
 from typing_extensions import override
 
 from fixtures.benchmark_fixture import MetricReport, NeonBenchmarker
@@ -24,11 +23,14 @@ from fixtures.neon_fixtures import (
     VanillaPostgres,
     wait_for_last_flush_lsn,
 )
-from fixtures.pg_stats import PgStatTable
 
 if TYPE_CHECKING:
     from collections.abc import Iterator
 
+    from _pytest.fixtures import FixtureRequest
+
+    from fixtures.pg_stats import PgStatTable
+
 
 class PgCompare(ABC):
     """Common interface of all postgres implementations, useful for benchmarks.

test_runner/fixtures/compute_reconfigure.py

@@ -4,8 +4,6 @@ import concurrent.futures
 from typing import TYPE_CHECKING
 
 import pytest
-from pytest_httpserver import HTTPServer
-from werkzeug.wrappers.request import Request
 from werkzeug.wrappers.response import Response
 
 from fixtures.common_types import TenantId
@@ -15,6 +13,9 @@ if TYPE_CHECKING:
     from collections.abc import Callable
     from typing import Any
 
+    from pytest_httpserver import HTTPServer
+    from werkzeug.wrappers.request import Request
+
 
 class ComputeReconfigure:
     def __init__(self, server: HTTPServer):

test_runner/fixtures/fast_import.py

@@ -147,7 +147,7 @@ def fast_import(
         pg_distrib_dir,
         pg_version,
         workdir,
-        cleanup=not cast(bool, pytestconfig.getoption("--preserve-database-files")),
+        cleanup=not cast("bool", pytestconfig.getoption("--preserve-database-files")),
     ) as fi:
         yield fi
 

test_runner/fixtures/h2server.py

@@ -10,7 +10,6 @@ import asyncio
 import collections
 import io
 import json
-from collections.abc import AsyncIterable
 from typing import TYPE_CHECKING, final
 
 import pytest_asyncio
@@ -31,6 +30,7 @@ from h2.settings import SettingCodes
 from typing_extensions import override
 
 if TYPE_CHECKING:
+    from collections.abc import AsyncIterable
     from typing import Any
 
 

test_runner/fixtures/metrics.py

@@ -1,12 +1,15 @@
 from __future__ import annotations
 
 from collections import defaultdict
+from typing import TYPE_CHECKING
 
 from prometheus_client.parser import text_string_to_metric_families
-from prometheus_client.samples import Sample
 
 from fixtures.log_helper import log
 
+if TYPE_CHECKING:
+    from prometheus_client.samples import Sample
+
 
 class Metrics:
     metrics: dict[str, list[Sample]]

test_runner/fixtures/neon_cli.py

@@ -7,7 +7,6 @@ import subprocess
 import tempfile
 import textwrap
 from itertools import chain, product
-from pathlib import Path
 from typing import TYPE_CHECKING, cast
 
 import toml
@@ -15,14 +14,15 @@ import toml
 from fixtures.common_types import Lsn, TenantId, TimelineId
 from fixtures.log_helper import log
 from fixtures.pageserver.common_types import IndexPartDump
-from fixtures.pg_version import PgVersion
 
 if TYPE_CHECKING:
+    from pathlib import Path
     from typing import (
         Any,
-        cast,
     )
 
+    from fixtures.pg_version import PgVersion
+
 
 # Used to be an ABC. abc.ABC removed due to linter without name change.
 class AbstractNeonCli:
@@ -36,7 +36,7 @@ class AbstractNeonCli:
         self.extra_env = extra_env
         self.binpath = binpath
 
-    COMMAND: str = cast(str, None)  # To be overwritten by the derived class.
+    COMMAND: str = cast("str", None)  # To be overwritten by the derived class.
 
     def raw_cli(
         self,

test_runner/fixtures/neon_fixtures.py

@@ -14,14 +14,12 @@ import threading
 import time
 import uuid
 from collections import defaultdict
-from collections.abc import Iterable, Iterator
 from contextlib import closing, contextmanager
 from dataclasses import dataclass
 from datetime import datetime
 from enum import StrEnum
 from functools import cached_property
 from pathlib import Path
-from types import TracebackType
 from typing import TYPE_CHECKING, cast
 from urllib.parse import quote, urlparse
 
@@ -34,19 +32,12 @@ import psycopg2.sql
 import pytest
 import requests
 import toml
-from _pytest.config import Config
-from _pytest.config.argparsing import Parser
-from _pytest.fixtures import FixtureRequest
 from jwcrypto import jwk
-from mypy_boto3_kms import KMSClient
-from mypy_boto3_s3 import S3Client
 
 # Type-related stuff
 from psycopg2.extensions import connection as PgConnection
 from psycopg2.extensions import cursor as PgCursor
 from psycopg2.extensions import make_dsn, parse_dsn
-from pytest_httpserver import HTTPServer
-from urllib3.util.retry import Retry
 
 from fixtures import overlayfs
 from fixtures.auth_tokens import AuthKeys, TokenScope
@@ -60,7 +51,6 @@ from fixtures.common_types import (
 )
 from fixtures.compute_migrations import NUM_COMPUTE_MIGRATIONS
 from fixtures.endpoint.http import EndpointHttpClient
-from fixtures.h2server import H2Server
 from fixtures.log_helper import log
 from fixtures.metrics import Metrics, MetricsGetter, parse_metrics
 from fixtures.neon_cli import NeonLocalCli, Pagectl
@@ -78,7 +68,6 @@ from fixtures.pageserver.utils import (
     wait_for_last_record_lsn,
 )
 from fixtures.paths import get_test_repo_dir, shared_snapshot_dir
-from fixtures.pg_version import PgVersion
 from fixtures.port_distributor import PortDistributor
 from fixtures.remote_storage import (
     LocalFsStorage,
@@ -108,10 +97,21 @@ from fixtures.utils import (
 from .neon_api import NeonAPI, NeonApiEndpoint
 
 if TYPE_CHECKING:
-    from collections.abc import Callable
+    from collections.abc import Callable, Iterable, Iterator
+    from types import TracebackType
     from typing import Any, Self, TypeVar
 
+    from _pytest.config import Config
+    from _pytest.config.argparsing import Parser
+    from _pytest.fixtures import FixtureRequest
+    from mypy_boto3_kms import KMSClient
+    from mypy_boto3_s3 import S3Client
+    from pytest_httpserver import HTTPServer
+    from urllib3.util.retry import Retry
+
+    from fixtures.h2server import H2Server
     from fixtures.paths import SnapshotDirLocked
+    from fixtures.pg_version import PgVersion
 
     T = TypeVar("T")
 
@@ -497,9 +497,9 @@ class NeonEnvBuilder:
         else:
             self.pageserver_wal_receiver_protocol = PageserverWalReceiverProtocol.INTERPRETED
 
-        assert test_name.startswith(
+        assert test_name.startswith("test_"), (
-            "test_"
+            "Unexpectedly instantiated from outside a test function"
-        ), "Unexpectedly instantiated from outside a test function"
+        )
         self.test_name = test_name
         self.compatibility_neon_binpath = compatibility_neon_binpath
         self.compatibility_pg_distrib_dir = compatibility_pg_distrib_dir
@@ -508,12 +508,12 @@ class NeonEnvBuilder:
         self.mixdir = self.test_output_dir / "mixdir_neon"
 
         if self.version_combination is not None:
-            assert (
+            assert self.compatibility_neon_binpath is not None, (
-                self.compatibility_neon_binpath is not None
+                "the environment variable COMPATIBILITY_NEON_BIN is required when using mixed versions"
-            ), "the environment variable COMPATIBILITY_NEON_BIN is required when using mixed versions"
+            )
-            assert (
+            assert self.compatibility_pg_distrib_dir is not None, (
-                self.compatibility_pg_distrib_dir is not None
+                "the environment variable COMPATIBILITY_POSTGRES_DISTRIB_DIR is required when using mixed versions"
-            ), "the environment variable COMPATIBILITY_POSTGRES_DISTRIB_DIR is required when using mixed versions"
+            )
             self.mixdir.mkdir(mode=0o755, exist_ok=True)
             self._mix_versions()
             self.test_may_use_compatibility_snapshot_binaries = True
@@ -795,9 +795,9 @@ class NeonEnvBuilder:
         work = ident_state_dir / "work"
         assert upper.is_dir()
         assert work.is_dir()
-        assert (
+        assert self.test_overlay_dir not in dst.parents, (
-            self.test_overlay_dir not in dst.parents
+            "otherwise workdir cleanup below wouldn't work"
-        ), "otherwise workdir cleanup below wouldn't work"
+        )
         # find index, still not mutating state
         idxmap = {
             existing_ident: idx
@@ -863,9 +863,9 @@ class NeonEnvBuilder:
         self.pageserver_remote_storage = ret
 
     def enable_safekeeper_remote_storage(self, kind: RemoteStorageKind):
-        assert (
+        assert self.safekeepers_remote_storage is None, (
-            self.safekeepers_remote_storage is None
+            "safekeepers_remote_storage already configured"
-        ), "safekeepers_remote_storage already configured"
+        )
 
         self.safekeepers_remote_storage = self._configure_and_create_remote_storage(
             kind, RemoteStorageUser.SAFEKEEPER
@@ -1421,9 +1421,9 @@ class NeonEnv:
         assert that there is only one. Tests with multiple pageservers should always use
         get_pageserver with an explicit ID.
         """
-        assert (
+        assert len(self.pageservers) == 1, (
-            len(self.pageservers) == 1
+            "env.pageserver must only be used with single pageserver NeonEnv"
-        ), "env.pageserver must only be used with single pageserver NeonEnv"
+        )
         return self.pageservers[0]
 
     def get_pageserver(self, id: int | None) -> NeonPageserver:
@@ -1614,7 +1614,7 @@ def neon_simple_env(
         compatibility_pg_distrib_dir=compatibility_pg_distrib_dir,
         pg_version=pg_version,
         run_id=run_id,
-        preserve_database_files=cast(bool, pytestconfig.getoption("--preserve-database-files")),
+        preserve_database_files=cast("bool", pytestconfig.getoption("--preserve-database-files")),
         test_name=request.node.name,
         test_output_dir=test_output_dir,
         pageserver_virtual_file_io_engine=pageserver_virtual_file_io_engine,
@@ -1683,7 +1683,7 @@ def neon_env_builder(
         combination=combination,
         pg_version=pg_version,
         run_id=run_id,
-        preserve_database_files=cast(bool, pytestconfig.getoption("--preserve-database-files")),
+        preserve_database_files=cast("bool", pytestconfig.getoption("--preserve-database-files")),
         pageserver_virtual_file_io_engine=pageserver_virtual_file_io_engine,
         test_name=request.node.name,
         test_output_dir=test_output_dir,
@@ -3577,9 +3577,9 @@ class NeonProxy(PgProtocol):
 
     @backoff.on_exception(backoff.expo, requests.exceptions.RequestException, max_time=10)
     def _wait_until_ready(self):
-        assert (
+        assert self._popen and self._popen.poll() is None, (
-            self._popen and self._popen.poll() is None
+            "Proxy exited unexpectedly. Check test log."
-        ), "Proxy exited unexpectedly. Check test log."
+        )
         requests.get(f"http://{self.host}:{self.http_port}/v1/status")
 
     def http_query(self, query, args, **kwargs):
@@ -3787,9 +3787,9 @@ class NeonAuthBroker:
 
     @backoff.on_exception(backoff.expo, requests.exceptions.RequestException, max_time=10)
     def _wait_until_ready(self):
-        assert (
+        assert self._popen and self._popen.poll() is None, (
-            self._popen and self._popen.poll() is None
+            "Proxy exited unexpectedly. Check test log."
-        ), "Proxy exited unexpectedly. Check test log."
+        )
         requests.get(f"http://{self.host}:{self.http_port}/v1/status")
 
     async def query(self, query, args, **kwargs):
@@ -4069,9 +4069,9 @@ class Endpoint(PgProtocol, LogUtils):
                     m = re.search(r"=\s*(\S+)", line)
                     assert m is not None, f"malformed config line {line}"
                     size = m.group(1)
-                    assert size_to_bytes(size) >= size_to_bytes(
+                    assert size_to_bytes(size) >= size_to_bytes("1MB"), (
-                        "1MB"
+                        "LFC size cannot be set less than 1MB"
-                    ), "LFC size cannot be set less than 1MB"
+                    )
             lfc_path_escaped = str(lfc_path).replace("'", "''")
             config_lines = [
                 f"neon.file_cache_path = '{lfc_path_escaped}'",
@@ -4082,12 +4082,12 @@ class Endpoint(PgProtocol, LogUtils):
             ] + config_lines
         else:
             for line in config_lines:
-                assert (
+                assert line.find("neon.max_file_cache_size") == -1, (
-                    line.find("neon.max_file_cache_size") == -1
+                    "Setting LFC parameters is not allowed when LFC is disabled"
-                ), "Setting LFC parameters is not allowed when LFC is disabled"
+                )
-                assert (
+                assert line.find("neon.file_cache_size_limit") == -1, (
-                    line.find("neon.file_cache_size_limit") == -1
+                    "Setting LFC parameters is not allowed when LFC is disabled"
-                ), "Setting LFC parameters is not allowed when LFC is disabled"
+                )
 
         self.config(config_lines)
 
@@ -4925,9 +4925,9 @@ class StorageScrubber:
                     healthy = False
             else:
                 for _, warnings in with_warnings.items():
-                    assert (
+                    assert len(warnings) > 0, (
-                        len(warnings) > 0
+                        "with_warnings value should not be empty, running without verbose mode?"
-                    ), "with_warnings value should not be empty, running without verbose mode?"
+                    )
                     if not self._check_line_list_allowed(warnings):
                         healthy = False
                         break
@@ -4941,9 +4941,9 @@ class StorageScrubber:
                     healthy = False
             else:
                 for _, errors in with_errors.items():
-                    assert (
+                    assert len(errors) > 0, (
-                        len(errors) > 0
+                        "with_errors value should not be empty, running without verbose mode?"
-                    ), "with_errors value should not be empty, running without verbose mode?"
+                    )
                     if not self._check_line_list_allowed(errors):
                         healthy = False
                         break

test_runner/fixtures/pageserver/allowed_errors.py

@@ -5,7 +5,10 @@ from __future__ import annotations
 import argparse
 import re
 import sys
-from collections.abc import Iterable
+from typing import TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from collections.abc import Iterable
 
 
 def scan_pageserver_log_for_errors(

test_runner/fixtures/pageserver/http.py

@@ -7,8 +7,7 @@ import string
 import time
 from collections import defaultdict
 from dataclasses import dataclass
-from datetime import datetime
+from typing import TYPE_CHECKING, Any
-from typing import Any
 
 import requests
 from requests.adapters import HTTPAdapter
@@ -26,6 +25,9 @@ from fixtures.metrics import Metrics, MetricsGetter, parse_metrics
 from fixtures.pg_version import PgVersion
 from fixtures.utils import EnhancedJSONEncoder, Fn
 
+if TYPE_CHECKING:
+    from datetime import datetime
+
 
 class PageserverApiException(Exception):
     def __init__(self, message, status_code: int):

test_runner/fixtures/pageserver/many_tenants.py

@@ -4,18 +4,19 @@ import concurrent.futures
 from typing import TYPE_CHECKING
 
 import fixtures.pageserver.remote_storage
-from fixtures.common_types import TenantId, TimelineId
 from fixtures.log_helper import log
-from fixtures.neon_fixtures import (
-    NeonEnv,
-    NeonEnvBuilder,
-)
 from fixtures.remote_storage import LocalFsStorage, RemoteStorageKind
 
 if TYPE_CHECKING:
     from collections.abc import Callable
     from typing import Any
 
+    from fixtures.common_types import TenantId, TimelineId
+    from fixtures.neon_fixtures import (
+        NeonEnv,
+        NeonEnvBuilder,
+    )
+
 
 def single_timeline(
     neon_env_builder: NeonEnvBuilder,

test_runner/fixtures/pageserver/remote_storage.py

@@ -5,11 +5,9 @@ import os
 import queue
 import shutil
 import threading
-from pathlib import Path
 from typing import TYPE_CHECKING
 
 from fixtures.common_types import TenantId, TimelineId
-from fixtures.neon_fixtures import NeonEnv
 from fixtures.pageserver.common_types import (
     InvalidFileName,
     parse_layer_file_name,
@@ -17,8 +15,11 @@ from fixtures.pageserver.common_types import (
 from fixtures.remote_storage import LocalFsStorage
 
 if TYPE_CHECKING:
+    from pathlib import Path
     from typing import Any
 
+    from fixtures.neon_fixtures import NeonEnv
+
 
 def duplicate_one_tenant(env: NeonEnv, template_tenant: TenantId, new_tenant: TenantId):
     remote_storage = env.pageserver_remote_storage

test_runner/fixtures/pageserver/utils.py

@@ -3,13 +3,6 @@ from __future__ import annotations
 import time
 from typing import TYPE_CHECKING
 
-from mypy_boto3_s3.type_defs import (
-    DeleteObjectOutputTypeDef,
-    EmptyResponseMetadataTypeDef,
-    ListObjectsV2OutputTypeDef,
-    ObjectTypeDef,
-)
-
 from fixtures.common_types import Lsn, TenantId, TenantShardId, TimelineId
 from fixtures.log_helper import log
 from fixtures.pageserver.http import PageserverApiException, PageserverHttpClient
@@ -19,6 +12,13 @@ from fixtures.utils import wait_until
 if TYPE_CHECKING:
     from typing import Any
 
+    from mypy_boto3_s3.type_defs import (
+        DeleteObjectOutputTypeDef,
+        EmptyResponseMetadataTypeDef,
+        ListObjectsV2OutputTypeDef,
+        ObjectTypeDef,
+    )
+
 
 def assert_tenant_state(
     pageserver_http: PageserverHttpClient,
@@ -241,9 +241,9 @@ def wait_for_upload_queue_empty(
             found = False
             for f in finished:
                 if all([s.labels[label] == f.labels[label] for label in remaining_labels]):
-                    assert (
+                    assert not found, (
-                        not found
+                        "duplicate match, remaining_labels don't uniquely identify sample"
-                    ), "duplicate match, remaining_labels don't uniquely identify sample"
+                    )
                     tl.append((s.labels, int(s.value) - int(f.value)))
                     found = True
             if not found:

test_runner/fixtures/parametrize.py

@@ -6,13 +6,14 @@ from typing import TYPE_CHECKING
 import allure
 import pytest
 import toml
-from _pytest.python import Metafunc
 
 from fixtures.pg_version import PgVersion
 
 if TYPE_CHECKING:
     from typing import Any
 
+    from _pytest.python import Metafunc
+
 
 """
 Dynamically parametrize tests by different parameters

test_runner/fixtures/paths.py

@@ -6,7 +6,6 @@ import subprocess
 import threading
 from fcntl import LOCK_EX, LOCK_UN, flock
 from pathlib import Path
-from types import TracebackType
 from typing import TYPE_CHECKING
 
 import pytest
@@ -18,6 +17,7 @@ from fixtures.utils import allure_attach_from_dir
 
 if TYPE_CHECKING:
     from collections.abc import Iterator
+    from types import TracebackType
 
 
 BASE_DIR = Path(__file__).parents[2]
@@ -101,9 +101,9 @@ def compatibility_snapshot_dir() -> Iterator[Path]:
     if os.getenv("REMOTE_ENV"):
         return
     compatibility_snapshot_dir_env = os.environ.get("COMPATIBILITY_SNAPSHOT_DIR")
-    assert (
+    assert compatibility_snapshot_dir_env is not None, (
-        compatibility_snapshot_dir_env is not None
+        "COMPATIBILITY_SNAPSHOT_DIR is not set. It should be set to `compatibility_snapshot_pg(PG_VERSION)` path generateted by test_create_snapshot (ideally generated by the previous version of Neon)"
-    ), "COMPATIBILITY_SNAPSHOT_DIR is not set. It should be set to `compatibility_snapshot_pg(PG_VERSION)` path generateted by test_create_snapshot (ideally generated by the previous version of Neon)"
+    )
     compatibility_snapshot_dir = Path(compatibility_snapshot_dir_env).resolve()
     yield compatibility_snapshot_dir
 

test_runner/fixtures/remote_storage.py

@@ -7,22 +7,24 @@ import os
 import re
 from dataclasses import dataclass
 from enum import StrEnum
-from pathlib import Path
 from typing import TYPE_CHECKING
 
 import boto3
 import toml
 from moto.server import ThreadedMotoServer
-from mypy_boto3_s3 import S3Client
 from typing_extensions import override
 
-from fixtures.common_types import TenantId, TenantShardId, TimelineId
 from fixtures.log_helper import log
 from fixtures.pageserver.common_types import IndexPartDump
 
 if TYPE_CHECKING:
+    from pathlib import Path
     from typing import Any
 
+    from mypy_boto3_s3 import S3Client
+
+    from fixtures.common_types import TenantId, TenantShardId, TimelineId
+
 
 TIMELINE_INDEX_PART_FILE_NAME = "index_part.json"
 TENANT_HEATMAP_FILE_NAME = "heatmap-v1.json"
@@ -448,9 +450,9 @@ class RemoteStorageKind(StrEnum):
         env_secret_key = os.getenv("AWS_SECRET_ACCESS_KEY")
         env_access_token = os.getenv("AWS_SESSION_TOKEN")
         env_profile = os.getenv("AWS_PROFILE")
-        assert (
+        assert (env_access_key and env_secret_key and env_access_token) or env_profile, (
-            env_access_key and env_secret_key and env_access_token
+            "need to specify either access key and secret access key or profile"
-        ) or env_profile, "need to specify either access key and secret access key or profile"
+        )
 
         bucket_name = bucket_name or os.getenv("REMOTE_STORAGE_S3_BUCKET")
         assert bucket_name is not None, "no remote storage bucket name provided"

test_runner/fixtures/reruns.py

@@ -3,12 +3,11 @@ from __future__ import annotations
 from collections.abc import MutableMapping
 from typing import TYPE_CHECKING, cast
 
-import pytest
-
 if TYPE_CHECKING:
     from collections.abc import MutableMapping
     from typing import Any
 
+    import pytest
     from _pytest.config import Config
 
 

test_runner/fixtures/safekeeper/utils.py

@@ -1,10 +1,14 @@
 from __future__ import annotations
 
-from fixtures.common_types import TenantId, TimelineId
+from typing import TYPE_CHECKING
+
 from fixtures.log_helper import log
-from fixtures.safekeeper.http import SafekeeperHttpClient
 from fixtures.utils import wait_until
 
+if TYPE_CHECKING:
+    from fixtures.common_types import TenantId, TimelineId
+    from fixtures.safekeeper.http import SafekeeperHttpClient
+
 
 def wait_walreceivers_absent(
     sk_http_cli: SafekeeperHttpClient, tenant_id: TenantId, timeline_id: TimelineId

test_runner/fixtures/slow.py

@@ -3,12 +3,13 @@ from __future__ import annotations
 from typing import TYPE_CHECKING
 
 import pytest
-from _pytest.config import Config
-from _pytest.config.argparsing import Parser
 
 if TYPE_CHECKING:
     from typing import Any
 
+    from _pytest.config import Config
+    from _pytest.config.argparsing import Parser
+
 
 """
 This plugin allows tests to be marked as slow using pytest.mark.slow. By default slow

test_runner/fixtures/storage_controller_proxy.py

@@ -5,9 +5,7 @@ from typing import TYPE_CHECKING
 
 import pytest
 import requests
-from pytest_httpserver import HTTPServer
 from werkzeug.datastructures import Headers
-from werkzeug.wrappers.request import Request
 from werkzeug.wrappers.response import Response
 
 from fixtures.log_helper import log
@@ -15,6 +13,9 @@ from fixtures.log_helper import log
 if TYPE_CHECKING:
     from typing import Any
 
+    from pytest_httpserver import HTTPServer
+    from werkzeug.wrappers.request import Request
+
 
 class StorageControllerProxy:
     def __init__(self, server: HTTPServer):

test_runner/fixtures/utils.py

@@ -19,7 +19,6 @@ from urllib.parse import urlencode
 import allure
 import pytest
 import zstandard
-from psycopg2.extensions import cursor
 from typing_extensions import override
 
 from fixtures.common_types import Id, Lsn
@@ -34,6 +33,8 @@ if TYPE_CHECKING:
     from collections.abc import Iterable
     from typing import IO
 
+    from psycopg2.extensions import cursor
+
     from fixtures.common_types import TimelineId
     from fixtures.neon_fixtures import PgBin
 
@@ -512,7 +513,9 @@ def assert_no_errors(log_file: Path, service: str, allowed_errors: list[str]):
     for _lineno, error in errors:
         log.info(f"not allowed {service} error: {error.strip()}")
 
-    assert not errors, f"First log error on {service}: {errors[0]}\nHint: use scripts/check_allowed_errors.sh to test any new allowed_error you add"
+    assert not errors, (
+        f"First log error on {service}: {errors[0]}\nHint: use scripts/check_allowed_errors.sh to test any new allowed_error you add"
+    )
 
 
 def assert_pageserver_backups_equal(left: Path, right: Path, skip_files: set[str]):
@@ -550,18 +553,18 @@ def assert_pageserver_backups_equal(left: Path, right: Path, skip_files: set[str
 
     left_list, right_list = map(build_hash_list, [left, right])
 
-    assert len(left_list) == len(
+    assert len(left_list) == len(right_list), (
-        right_list
+        f"unexpected number of files on tar files, {len(left_list)} != {len(right_list)}"
-    ), f"unexpected number of files on tar files, {len(left_list)} != {len(right_list)}"
+    )
 
     mismatching: set[str] = set()
 
     for left_tuple, right_tuple in zip(left_list, right_list, strict=False):
         left_path, left_hash = left_tuple
         right_path, right_hash = right_tuple
-        assert (
+        assert left_path == right_path, (
-            left_path == right_path
+            f"file count matched, expected these to be same paths: {left_path}, {right_path}"
-        ), f"file count matched, expected these to be same paths: {left_path}, {right_path}"
+        )
         if left_hash != right_hash:
             mismatching.add(left_path)
 

test_runner/fixtures/workload.py

@@ -3,7 +3,6 @@ from __future__ import annotations
 import threading
 from typing import TYPE_CHECKING
 
-from fixtures.common_types import TenantId, TimelineId
 from fixtures.log_helper import log
 from fixtures.neon_fixtures import (
     Endpoint,
@@ -17,6 +16,8 @@ from fixtures.pageserver.utils import wait_for_last_record_lsn
 if TYPE_CHECKING:
     from typing import Any
 
+    from fixtures.common_types import TenantId, TimelineId
+
 # neon_local doesn't handle creating/modifying endpoints concurrently, so we use a mutex
 # to ensure we don't do that: this enables running lots of Workloads in parallel safely.
 ENDPOINT_LOCK = threading.Lock()

test_runner/logical_repl/test_clickhouse.py

@@ -7,14 +7,17 @@ from __future__ import annotations
 import hashlib
 import os
 import time
+from typing import TYPE_CHECKING
 
 import clickhouse_connect
 import psycopg2
 import pytest
 from fixtures.log_helper import log
-from fixtures.neon_fixtures import RemotePostgres
 from fixtures.utils import wait_until
 
+if TYPE_CHECKING:
+    from fixtures.neon_fixtures import RemotePostgres
+
 
 def query_clickhouse(
     client,

test_runner/logical_repl/test_debezium.py

@@ -7,14 +7,17 @@ from __future__ import annotations
 import json
 import os
 import time
+from typing import TYPE_CHECKING
 
 import psycopg2
 import pytest
 import requests
 from fixtures.log_helper import log
-from fixtures.neon_fixtures import RemotePostgres
 from fixtures.utils import wait_until
 
+if TYPE_CHECKING:
+    from fixtures.neon_fixtures import RemotePostgres
+
 
 class DebeziumAPI:
     """

test_runner/performance/pageserver/util.py

@@ -7,18 +7,19 @@ from __future__ import annotations
 from typing import TYPE_CHECKING
 
 import fixtures.pageserver.many_tenants as many_tenants
-from fixtures.common_types import TenantId, TimelineId
 from fixtures.log_helper import log
-from fixtures.neon_fixtures import (
-    NeonEnv,
-    NeonEnvBuilder,
-)
 from fixtures.pageserver.utils import wait_until_all_tenants_state
 
 if TYPE_CHECKING:
     from collections.abc import Callable
     from typing import Any
 
+    from fixtures.common_types import TenantId, TimelineId
+    from fixtures.neon_fixtures import (
+        NeonEnv,
+        NeonEnvBuilder,
+    )
+
 
 def ensure_pageserver_ready_for_benchmarking(env: NeonEnv, n_tenants: int):
     """

test_runner/performance/test_branch_creation.py

@@ -7,16 +7,19 @@ import threading
 import time
 import timeit
 from contextlib import closing
+from typing import TYPE_CHECKING
 
 import pytest
 from fixtures.benchmark_fixture import MetricReport, NeonBenchmarker
 from fixtures.common_types import Lsn
-from fixtures.compare_fixtures import NeonCompare
 from fixtures.log_helper import log
-from fixtures.neon_fixtures import NeonPageserver
 from fixtures.pageserver.utils import wait_for_last_record_lsn
 from fixtures.utils import wait_until
-from prometheus_client.samples import Sample
+
+if TYPE_CHECKING:
+    from fixtures.compare_fixtures import NeonCompare
+    from fixtures.neon_fixtures import NeonPageserver
+    from prometheus_client.samples import Sample
 
 
 def _record_branch_creation_durations(neon_compare: NeonCompare, durs: list[float]):
@@ -45,9 +48,9 @@ def test_branch_creation_heavy_write(neon_compare: NeonCompare, n_branches: int)
     tenant, _ = env.create_tenant(
         conf={
             "gc_period": "5 s",
-            "gc_horizon": f"{4 * 1024 ** 2}",
+            "gc_horizon": f"{4 * 1024**2}",
-            "checkpoint_distance": f"{2 * 1024 ** 2}",
+            "checkpoint_distance": f"{2 * 1024**2}",
-            "compaction_target_size": f"{1024 ** 2}",
+            "compaction_target_size": f"{1024**2}",
             "compaction_threshold": "2",
             # set PITR interval to be small, so we can do GC
             "pitr_interval": "5 s",
@@ -82,10 +85,10 @@ def test_branch_creation_heavy_write(neon_compare: NeonCompare, n_branches: int)
         env.create_branch(f"b{i + 1}", ancestor_branch_name=f"b{p}", tenant_id=tenant)
         dur = timeit.default_timer() - timer
 
-        log.info(f"Creating branch b{i+1} took {dur}s")
+        log.info(f"Creating branch b{i + 1} took {dur}s")
         branch_creation_durations.append(dur)
 
-        threads.append(threading.Thread(target=run_pgbench, args=(f"b{i+1}",), daemon=True))
+        threads.append(threading.Thread(target=run_pgbench, args=(f"b{i + 1}",), daemon=True))
         threads[-1].start()
 
     for thread in threads:

test_runner/performance/test_branching.py

@@ -2,13 +2,16 @@ from __future__ import annotations
 
 import timeit
 from pathlib import Path
+from typing import TYPE_CHECKING
 
 from fixtures.benchmark_fixture import PgBenchRunResult
-from fixtures.compare_fixtures import NeonCompare
 from fixtures.neon_fixtures import fork_at_current_lsn
 
 from performance.test_perf_pgbench import utc_now_timestamp
 
+if TYPE_CHECKING:
+    from fixtures.compare_fixtures import NeonCompare
+
 # -----------------------------------------------------------------------
 # Start of `test_compare_child_and_root_*` tests
 # -----------------------------------------------------------------------

test_runner/performance/test_bulk_tenant_create.py

@@ -1,10 +1,13 @@
 from __future__ import annotations
 
 import timeit
+from typing import TYPE_CHECKING
 
 import pytest
 from fixtures.benchmark_fixture import MetricReport
-from fixtures.neon_fixtures import NeonEnvBuilder
+
+if TYPE_CHECKING:
+    from fixtures.neon_fixtures import NeonEnvBuilder
 
 # Run bulk tenant creation test.
 #

test_runner/performance/test_compaction.py

@@ -1,12 +1,15 @@
 from __future__ import annotations
 
 from contextlib import closing
+from typing import TYPE_CHECKING
 
 import pytest
-from fixtures.compare_fixtures import NeonCompare
 from fixtures.log_helper import log
 from fixtures.neon_fixtures import wait_for_last_flush_lsn
 
+if TYPE_CHECKING:
+    from fixtures.compare_fixtures import NeonCompare
+
 
 #
 # Test compaction and image layer creation performance.

test_runner/performance/test_compare_pg_stats.py

@@ -3,13 +3,16 @@ from __future__ import annotations
 import os
 import threading
 import time
+from typing import TYPE_CHECKING
 
 import pytest
-from fixtures.compare_fixtures import PgCompare
-from fixtures.pg_stats import PgStatTable
 
 from performance.test_perf_pgbench import get_durations_matrix, get_scales_matrix
 
+if TYPE_CHECKING:
+    from fixtures.compare_fixtures import PgCompare
+    from fixtures.pg_stats import PgStatTable
+
 
 def get_seeds_matrix(default: int = 100):
     seeds = os.getenv("TEST_PG_BENCH_SEEDS_MATRIX", default=str(default))

test_runner/performance/test_compute_ctl_api.py

@@ -1,10 +1,13 @@
 from __future__ import annotations
 
 import datetime
+from typing import TYPE_CHECKING
 
 import pytest
 from fixtures.benchmark_fixture import MetricReport, NeonBenchmarker
-from fixtures.neon_fixtures import NeonEnv
+
+if TYPE_CHECKING:
+    from fixtures.neon_fixtures import NeonEnv
 
 
 @pytest.mark.timeout(120)

test_runner/performance/test_compute_startup.py

@@ -1,9 +1,13 @@
 from __future__ import annotations
 
+from typing import TYPE_CHECKING
+
 import pytest
 import requests
 from fixtures.benchmark_fixture import MetricReport, NeonBenchmarker
-from fixtures.neon_fixtures import NeonEnvBuilder, PgBin
+
+if TYPE_CHECKING:
+    from fixtures.neon_fixtures import NeonEnvBuilder, PgBin
 
 
 # Just start and measure duration.

test_runner/performance/test_copy.py

@@ -2,11 +2,13 @@ from __future__ import annotations
 
 from contextlib import closing
 from io import BufferedReader, RawIOBase
-from typing import final
+from typing import TYPE_CHECKING, final
 
-from fixtures.compare_fixtures import PgCompare
 from typing_extensions import override
 
+if TYPE_CHECKING:
+    from fixtures.compare_fixtures import PgCompare
+
 
 @final
 class CopyTestData(RawIOBase):

test_runner/performance/test_dup_key.py

@@ -1,11 +1,14 @@
 from __future__ import annotations
 
 from contextlib import closing
+from typing import TYPE_CHECKING
 
 import pytest
-from fixtures.compare_fixtures import PgCompare
 from pytest_lazyfixture import lazy_fixture
 
+if TYPE_CHECKING:
+    from fixtures.compare_fixtures import PgCompare
+
 
 @pytest.mark.parametrize(
     "env",

test_runner/performance/test_gc_feedback.py

@@ -1,11 +1,14 @@
 from __future__ import annotations
 
 import json
+from typing import TYPE_CHECKING
 
 import pytest
 from fixtures.benchmark_fixture import MetricReport, NeonBenchmarker
 from fixtures.log_helper import log
-from fixtures.neon_fixtures import NeonEnvBuilder
+
+if TYPE_CHECKING:
+    from fixtures.neon_fixtures import NeonEnvBuilder
 
 
 def gc_feedback_impl(neon_env_builder: NeonEnvBuilder, zenbenchmark: NeonBenchmarker, mode: str):
@@ -18,9 +21,9 @@ def gc_feedback_impl(neon_env_builder: NeonEnvBuilder, zenbenchmark: NeonBenchma
             # disable default GC and compaction
             "gc_period": "1000 m",
             "compaction_period": "0 s",
-            "gc_horizon": f"{1024 ** 2}",
+            "gc_horizon": f"{1024**2}",
-            "checkpoint_distance": f"{1024 ** 2}",
+            "checkpoint_distance": f"{1024**2}",
-            "compaction_target_size": f"{1024 ** 2}",
+            "compaction_target_size": f"{1024**2}",
             # set PITR interval to be small, so we can do GC
             "pitr_interval": "10 s",
             # "compaction_threshold": "3",

test_runner/performance/test_gist_build.py

@@ -1,8 +1,10 @@
 from __future__ import annotations
 
 from contextlib import closing
+from typing import TYPE_CHECKING
 
-from fixtures.compare_fixtures import PgCompare
+if TYPE_CHECKING:
+    from fixtures.compare_fixtures import PgCompare
 
 
 #

test_runner/performance/test_hot_page.py

@@ -1,11 +1,14 @@
 from __future__ import annotations
 
 from contextlib import closing
+from typing import TYPE_CHECKING
 
 import pytest
-from fixtures.compare_fixtures import PgCompare
 from pytest_lazyfixture import lazy_fixture
 
+if TYPE_CHECKING:
+    from fixtures.compare_fixtures import PgCompare
+
 
 @pytest.mark.parametrize(
     "env",

test_runner/performance/test_hot_table.py

@@ -1,11 +1,14 @@
 from __future__ import annotations
 
 from contextlib import closing
+from typing import TYPE_CHECKING
 
 import pytest
-from fixtures.compare_fixtures import PgCompare
 from pytest_lazyfixture import lazy_fixture
 
+if TYPE_CHECKING:
+    from fixtures.compare_fixtures import PgCompare
+
 
 @pytest.mark.parametrize(
     "env",

test_runner/performance/test_latency.py

@@ -1,18 +1,21 @@
 from __future__ import annotations
 
 import threading
+from typing import TYPE_CHECKING
 
 import pytest
-from fixtures.compare_fixtures import PgCompare
-from fixtures.neon_fixtures import PgProtocol
 
 from performance.test_perf_pgbench import get_scales_matrix
 from performance.test_wal_backpressure import record_read_latency
 
+if TYPE_CHECKING:
+    from fixtures.compare_fixtures import PgCompare
+    from fixtures.neon_fixtures import PgProtocol
+
 
 def start_write_workload(pg: PgProtocol, scale: int = 10):
     with pg.connect().cursor() as cur:
-        cur.execute(f"create table big as select generate_series(1,{scale*100_000})")
+        cur.execute(f"create table big as select generate_series(1,{scale * 100_000})")
 
 
 # Measure latency of reads on one table, while lots of writes are happening on another table.
@@ -24,7 +27,7 @@ def test_measure_read_latency_heavy_write_workload(neon_with_baseline: PgCompare
     pg = env.pg
 
     with pg.connect().cursor() as cur:
-        cur.execute(f"create table small as select generate_series(1,{scale*100_000})")
+        cur.execute(f"create table small as select generate_series(1,{scale * 100_000})")
 
     write_thread = threading.Thread(target=start_write_workload, args=(pg, scale * 100))
     write_thread.start()

test_runner/performance/test_logical_replication.py

@@ -1,7 +1,6 @@
 from __future__ import annotations
 
 import time
-from collections.abc import Iterator
 from contextlib import contextmanager
 from typing import TYPE_CHECKING, cast
 
@@ -14,6 +13,7 @@ from fixtures.log_helper import log
 from fixtures.neon_fixtures import logical_replication_sync
 
 if TYPE_CHECKING:
+    from collections.abc import Iterator
     from subprocess import Popen
     from typing import AnyStr
 

test_runner/performance/test_parallel_copy.py

@@ -2,8 +2,10 @@ from __future__ import annotations
 
 import asyncio
 from io import BytesIO
+from typing import TYPE_CHECKING
 
-from fixtures.neon_fixtures import Endpoint, NeonEnv
+if TYPE_CHECKING:
+    from fixtures.neon_fixtures import Endpoint, NeonEnv
 
 
 async def repeat_bytes(buf, repetitions: int):

test_runner/performance/test_parallel_copy_to.py

@@ -2,9 +2,11 @@ from __future__ import annotations
 
 import asyncio
 from io import BytesIO
+from typing import TYPE_CHECKING
 
-from fixtures.compare_fixtures import PgCompare
+if TYPE_CHECKING:
-from fixtures.neon_fixtures import PgProtocol
+    from fixtures.compare_fixtures import PgCompare
+    from fixtures.neon_fixtures import PgProtocol
 
 
 async def repeat_bytes(buf, repetitions: int):

test_runner/performance/test_perf_ingest_using_pgcopydb.py

@@ -134,8 +134,8 @@ def run_command_and_log_output(command, log_file_path: Path):
     # Define a list of necessary environment variables for pgcopydb
     custom_env_vars = {
         "LD_LIBRARY_PATH": f"{os.getenv('PGCOPYDB_LIB_PATH')}:{os.getenv('PG_16_LIB_PATH')}",
-        "PGCOPYDB_SOURCE_PGURI": cast(str, os.getenv("BENCHMARK_INGEST_SOURCE_CONNSTR")),
+        "PGCOPYDB_SOURCE_PGURI": cast("str", os.getenv("BENCHMARK_INGEST_SOURCE_CONNSTR")),
-        "PGCOPYDB_TARGET_PGURI": cast(str, os.getenv("BENCHMARK_INGEST_TARGET_CONNSTR")),
+        "PGCOPYDB_TARGET_PGURI": cast("str", os.getenv("BENCHMARK_INGEST_TARGET_CONNSTR")),
         "PGOPTIONS": "-c idle_in_transaction_session_timeout=0 -c maintenance_work_mem=8388608 -c max_parallel_maintenance_workers=7",
     }
     # Combine the current environment with custom variables

test_runner/performance/test_perf_olap.py

@@ -3,12 +3,15 @@ from __future__ import annotations
 import os
 from dataclasses import dataclass
 from pathlib import Path
+from typing import TYPE_CHECKING
 
 import pytest
-from _pytest.mark import ParameterSet
-from fixtures.compare_fixtures import RemoteCompare
 from fixtures.log_helper import log
 
+if TYPE_CHECKING:
+    from _pytest.mark import ParameterSet
+    from fixtures.compare_fixtures import RemoteCompare
+
 
 @dataclass
 class LabelledQuery:

test_runner/performance/test_perf_oltp_large_tenant.py

@@ -4,14 +4,17 @@ import os
 import timeit
 from contextlib import closing
 from pathlib import Path
+from typing import TYPE_CHECKING
 
 import pytest
 from fixtures.benchmark_fixture import PgBenchRunResult
-from fixtures.compare_fixtures import PgCompare
 from fixtures.log_helper import log
 
 from performance.test_perf_pgbench import get_durations_matrix, utc_now_timestamp
 
+if TYPE_CHECKING:
+    from fixtures.compare_fixtures import PgCompare
+
 
 def get_custom_scripts(
     default: str = "insert_webhooks.sql@2 select_any_webhook_with_skew.sql@4 select_recent_webhook.sql@4",

test_runner/performance/test_perf_pgbench.py

@@ -6,12 +6,15 @@ import os
 import timeit
 from datetime import datetime
 from pathlib import Path
+from typing import TYPE_CHECKING
 
 import pytest
 from fixtures.benchmark_fixture import MetricReport, PgBenchInitResult, PgBenchRunResult
-from fixtures.compare_fixtures import PgCompare
 from fixtures.utils import get_scale_for_db
 
+if TYPE_CHECKING:
+    from fixtures.compare_fixtures import PgCompare
+
 
 @enum.unique
 class PgBenchLoadType(enum.Enum):

test_runner/performance/test_perf_pgvector_queries.py

@@ -1,10 +1,14 @@
 from __future__ import annotations
 
+from typing import TYPE_CHECKING
+
 import pytest
-from fixtures.compare_fixtures import PgCompare
 
 from performance.test_perf_pgbench import PgBenchLoadType, get_durations_matrix, run_test_pgbench
 
+if TYPE_CHECKING:
+    from fixtures.compare_fixtures import PgCompare
+
 
 # The following test runs on an existing database that has pgvector extension installed
 # and a table with 1 million embedding vectors loaded and indexed with HNSW.

test_runner/performance/test_physical_replication.py

@@ -2,10 +2,8 @@ from __future__ import annotations
 
 import csv
 import os
-import subprocess
 import time
 import traceback
-from pathlib import Path
 from typing import TYPE_CHECKING
 
 import psycopg2
@@ -15,14 +13,16 @@ from fixtures.benchmark_fixture import MetricReport
 from fixtures.common_types import Lsn
 from fixtures.log_helper import log
 from fixtures.neon_api import connection_parameters_to_env
-from fixtures.pg_version import PgVersion
 
 if TYPE_CHECKING:
+    import subprocess
+    from pathlib import Path
     from typing import Any
 
     from fixtures.benchmark_fixture import NeonBenchmarker
     from fixtures.neon_api import NeonAPI
     from fixtures.neon_fixtures import PgBin
+    from fixtures.pg_version import PgVersion
 
 
 # Granularity of ~0.5 sec
@@ -186,7 +186,7 @@ def test_replication_start_stop(
     prefix = "pgbench_agg"
     num_replicas = 2
     configuration_test_time_sec = 10 * 60
-    pgbench_duration = f"-T{2 ** num_replicas * configuration_test_time_sec}"
+    pgbench_duration = f"-T{2**num_replicas * configuration_test_time_sec}"
     error_occurred = False
 
     project = neon_api.create_project(pg_version)

test_runner/performance/test_random_writes.py

@@ -2,11 +2,14 @@ from __future__ import annotations
 
 import random
 from contextlib import closing
+from typing import TYPE_CHECKING
 
 from fixtures.benchmark_fixture import MetricReport
-from fixtures.compare_fixtures import PgCompare
 from fixtures.utils import query_scalar
 
+if TYPE_CHECKING:
+    from fixtures.compare_fixtures import PgCompare
+
 
 # This is a clear-box test that demonstrates the worst case scenario for the
 # "1 segment per layer" implementation of the pageserver. It writes to random

test_runner/performance/test_seqscans.py

@@ -4,13 +4,16 @@
 from __future__ import annotations
 
 from contextlib import closing
+from typing import TYPE_CHECKING
 
 import pytest
 from fixtures.benchmark_fixture import MetricReport
-from fixtures.compare_fixtures import PgCompare
 from fixtures.log_helper import log
 from pytest_lazyfixture import lazy_fixture
 
+if TYPE_CHECKING:
+    from fixtures.compare_fixtures import PgCompare
+
 
 @pytest.mark.parametrize(
     "rows,iters,workers",

test_runner/performance/test_storage_controller_scale.py

@@ -5,10 +5,10 @@ import random
 import time
 from collections import defaultdict
 from enum import StrEnum
+from typing import TYPE_CHECKING
 
 import pytest
 from fixtures.common_types import TenantId, TenantShardId, TimelineArchivalState, TimelineId
-from fixtures.compute_reconfigure import ComputeReconfigure
 from fixtures.log_helper import log
 from fixtures.neon_fixtures import (
     NeonEnv,
@@ -22,6 +22,9 @@ from fixtures.pageserver.http import PageserverApiException, PageserverHttpClien
 from fixtures.pg_version import PgVersion
 from fixtures.utils import wait_until
 
+if TYPE_CHECKING:
+    from fixtures.compute_reconfigure import ComputeReconfigure
+
 
 def get_consistent_node_shard_counts(env: NeonEnv, total_shards) -> defaultdict[str, int]:
     """
@@ -171,7 +174,7 @@ def test_storage_controller_many_tenants(
 
         rss = env.storage_controller.get_metric_value("process_resident_memory_bytes")
         assert rss is not None
-        log.info(f"Resident memory: {rss} ({ rss / total_shards} per shard)")
+        log.info(f"Resident memory: {rss} ({rss / total_shards} per shard)")
         assert rss < expect_memory_per_shard * total_shards
 
     def assert_all_tenants_scheduled_in_home_az():
@@ -186,15 +189,15 @@ def test_storage_controller_many_tenants(
                     assert preferred_az == shard["preferred_az_id"]
 
                 # Attachment should be in the preferred AZ
-                assert shard["preferred_az_id"] == az_selector(
+                assert shard["preferred_az_id"] == az_selector(shard["node_attached"]), (
-                    shard["node_attached"]
+                    f"Shard {shard['tenant_shard_id']} not in {shard['preferred_az_id']}"
-                ), f"Shard {shard['tenant_shard_id']} not in {shard['preferred_az_id']}"
+                )
 
                 # Secondary locations should not be in the preferred AZ
                 for node_secondary in shard["node_secondary"]:
-                    assert (
+                    assert shard["preferred_az_id"] != az_selector(node_secondary), (
-                        shard["preferred_az_id"] != az_selector(node_secondary)
+                        f"Shard {shard['tenant_shard_id']} secondary should be in {shard['preferred_az_id']}"
-                    ), f"Shard {shard['tenant_shard_id']} secondary should be in {shard['preferred_az_id']}"
+                    )
 
                 # There should only be one secondary location (i.e. no migrations in flight)
                 assert len(shard["node_secondary"]) == 1
@@ -531,9 +534,9 @@ def test_storage_controller_many_tenants(
         for node in nodes:
             if node["id"] in node_ids:
                 checked_any = True
-                assert (
+                assert node["availability"] == expected_availability, (
-                    node["availability"] == expected_availability
+                    f"Node {node['id']} is not {expected_availability} yet: {node['availability']}"
-                ), f"Node {node['id']} is not {expected_availability} yet: {node['availability']}"
+                )
 
         assert checked_any
 
@@ -550,9 +553,9 @@ def test_storage_controller_many_tenants(
         desc = env.storage_controller.tenant_describe(tenant_id)
         for shard in desc["shards"]:
             # Attachment should be outside the AZ where we killed the pageservers
-            assert (
+            assert az_selector(shard["node_attached"]) != victim_az, (
-                az_selector(shard["node_attached"]) != victim_az
+                f"Shard {shard['tenant_shard_id']} still in {victim_az} (node {shard['node_attached']})"
-            ), f"Shard {shard['tenant_shard_id']} still in {victim_az} (node {shard['node_attached']})"
+            )
 
     # Bring back the pageservers
     for ps in killed_pageservers:

test_runner/performance/test_wal_backpressure.py

@@ -4,7 +4,6 @@ import statistics
 import threading
 import time
 import timeit
-from collections.abc import Generator
 from typing import TYPE_CHECKING
 
 import pytest
@@ -17,7 +16,7 @@ from fixtures.neon_fixtures import NeonEnvBuilder, PgBin, flush_ep_to_pageserver
 from performance.test_perf_pgbench import get_durations_matrix, get_scales_matrix
 
 if TYPE_CHECKING:
-    from collections.abc import Callable
+    from collections.abc import Callable, Generator
     from typing import Any
 
 
@@ -37,9 +36,9 @@ def pg_compare(request) -> Generator[PgCompare, None, None]:
 
         yield fixture
     else:
-        assert (
+        assert len(x) == 2, (
-            len(x) == 2
+            f"request param ({request.param}) should have a format of `neon_{{safekeepers_enable_fsync}}`"
-        ), f"request param ({request.param}) should have a format of `neon_{{safekeepers_enable_fsync}}`"
+        )
 
         # `NeonCompare` interface
         neon_env_builder = request.getfixturevalue("neon_env_builder")
@@ -278,7 +277,7 @@ def record_read_latency(
                 t2 = timeit.default_timer()
 
                 log.info(
-                    f"Executed read query {read_query}, got {cur.fetchall()}, read time {t2-t1:.2f}s"
+                    f"Executed read query {read_query}, got {cur.fetchall()}, read time {t2 - t1:.2f}s"
                 )
                 read_latencies.append(t2 - t1)
             except Exception as err:

test_runner/performance/test_write_amplification.py

@@ -14,8 +14,10 @@
 from __future__ import annotations
 
 from contextlib import closing
+from typing import TYPE_CHECKING
 
-from fixtures.compare_fixtures import PgCompare
+if TYPE_CHECKING:
+    from fixtures.compare_fixtures import PgCompare
 
 
 def test_write_amplification(neon_with_baseline: PgCompare):

test_runner/pg_clients/test_pg_clients.py

@@ -3,11 +3,14 @@ from __future__ import annotations
 import shutil
 from pathlib import Path
 from tempfile import NamedTemporaryFile
+from typing import TYPE_CHECKING
 
 import pytest
-from fixtures.neon_fixtures import RemotePostgres
 from fixtures.utils import subprocess_capture
 
+if TYPE_CHECKING:
+    from fixtures.neon_fixtures import RemotePostgres
+
 
 @pytest.mark.remote_cluster
 @pytest.mark.parametrize(

test_runner/regress/test_ancestor_branch.py

@@ -1,10 +1,14 @@
 from __future__ import annotations
 
+from typing import TYPE_CHECKING
+
 from fixtures.common_types import TimelineId
 from fixtures.log_helper import log
-from fixtures.neon_fixtures import NeonEnvBuilder
 from fixtures.utils import query_scalar
 
+if TYPE_CHECKING:
+    from fixtures.neon_fixtures import NeonEnvBuilder
+
 
 #
 # Create ancestor branches off the main branch.

test_runner/regress/test_attach_tenant_config.py

@@ -1,19 +1,23 @@
 from __future__ import annotations
 
-from collections.abc import Generator
 from dataclasses import dataclass
+from typing import TYPE_CHECKING
 
 import pytest
 from fixtures.common_types import TenantId
 from fixtures.log_helper import log
-from fixtures.neon_fixtures import (
-    NeonEnv,
-    NeonEnvBuilder,
-)
-from fixtures.pageserver.http import PageserverHttpClient, TenantConfig
 from fixtures.remote_storage import LocalFsStorage, RemoteStorageKind
 from fixtures.utils import wait_until
 
+if TYPE_CHECKING:
+    from collections.abc import Generator
+
+    from fixtures.neon_fixtures import (
+        NeonEnv,
+        NeonEnvBuilder,
+    )
+    from fixtures.pageserver.http import PageserverHttpClient, TenantConfig
+
 
 @pytest.fixture
 def positive_env(neon_env_builder: NeonEnvBuilder) -> NeonEnv:
@@ -53,9 +57,9 @@ def negative_env(neon_env_builder: NeonEnvBuilder) -> Generator[NegativeTests, N
 
     yield NegativeTests(env, tenant_id, config_pre_detach)
 
-    assert tenant_id not in [
+    assert tenant_id not in [TenantId(t["id"]) for t in ps_http.tenant_list()], (
-        TenantId(t["id"]) for t in ps_http.tenant_list()
+        "tenant should not be attached after negative test"
-    ], "tenant should not be attached after negative test"
+    )
 
     env.pageserver.allowed_errors.extend(
         [
@@ -214,9 +218,9 @@ def test_fully_custom_config(positive_env: NeonEnv):
     # also self-test that our fully_custom_config covers all of them
     initial_tenant_config = get_config(ps_http, env.initial_tenant)
     assert initial_tenant_config.tenant_specific_overrides == {}
-    assert set(initial_tenant_config.effective_config.keys()) == set(
+    assert set(initial_tenant_config.effective_config.keys()) == set(fully_custom_config.keys()), (
-        fully_custom_config.keys()
+        "ensure we cover all config options"
-    ), "ensure we cover all config options"
+    )
 
     # create a new tenant to test overrides
     (tenant_id, _) = env.create_tenant()
@@ -237,17 +241,15 @@ def test_fully_custom_config(positive_env: NeonEnv):
 
         # some more self-validation: assert that none of the values in our
         # fully custom config are the same as the default values
-        assert set(our_tenant_config.effective_config.keys()) == set(
+        assert set(our_tenant_config.effective_config.keys()) == set(fully_custom_config.keys()), (
-            fully_custom_config.keys()
+            "ensure we cover all config options"
-        ), "ensure we cover all config options"
+        )
-        assert (
+        assert {
-            {
+            k: initial_tenant_config.effective_config[k] != our_tenant_config.effective_config[k]
-                k: initial_tenant_config.effective_config[k]
+            for k in fully_custom_config.keys()
-                != our_tenant_config.effective_config[k]
+        } == {k: True for k in fully_custom_config.keys()}, (
-                for k in fully_custom_config.keys()
+            "ensure our custom config has different values than the default config for all config options, so we know we overrode everything"
-            }
+        )
-            == {k: True for k in fully_custom_config.keys()}
-        ), "ensure our custom config has different values than the default config for all config options, so we know we overrode everything"
 
         # ensure customizations survive reattach
         env.pageserver.tenant_detach(tenant_id)

test_runner/regress/test_auth_broker.py

@@ -23,13 +23,13 @@ async def test_auth_broker_happy(
     # local proxy mock just echos back the request
     # check that we forward the correct data
 
-    assert (
+    assert res["headers"]["authorization"] == f"Bearer {token.serialize()}", (
-        res["headers"]["authorization"] == f"Bearer {token.serialize()}"
+        "JWT should be forwarded"
-    ), "JWT should be forwarded"
+    )
 
-    assert (
+    assert "anonymous" in res["headers"]["neon-connection-string"], (
-        "anonymous" in res["headers"]["neon-connection-string"]
+        "conn string should be forwarded"
-    ), "conn string should be forwarded"
+    )
 
     assert json.loads(res["body"]) == {
         "query": "foo",

test_runner/regress/test_backpressure.py

@@ -3,11 +3,14 @@ from __future__ import annotations
 import threading
 import time
 from contextlib import closing, contextmanager
+from typing import TYPE_CHECKING
 
 import psycopg2.extras
 import pytest
 from fixtures.log_helper import log
-from fixtures.neon_fixtures import Endpoint, NeonEnvBuilder
+
+if TYPE_CHECKING:
+    from fixtures.neon_fixtures import Endpoint, NeonEnvBuilder
 
 pytest_plugins = "fixtures.neon_fixtures"
 

test_runner/regress/test_bad_connection.py

@@ -2,13 +2,16 @@ from __future__ import annotations
 
 import random
 import time
+from typing import TYPE_CHECKING
 
 import psycopg2.errors
 import pytest
 from fixtures.log_helper import log
-from fixtures.neon_fixtures import NeonEnvBuilder
 from fixtures.utils import USE_LFC
 
+if TYPE_CHECKING:
+    from fixtures.neon_fixtures import NeonEnvBuilder
+
 
 @pytest.mark.timeout(600)
 def test_compute_pageserver_connection_stress(neon_env_builder: NeonEnvBuilder):

test_runner/regress/test_basebackup_error.py

@@ -1,7 +1,11 @@
 from __future__ import annotations
 
+from typing import TYPE_CHECKING
+
 import pytest
-from fixtures.neon_fixtures import NeonEnv
+
+if TYPE_CHECKING:
+    from fixtures.neon_fixtures import NeonEnv
 
 
 #

test_runner/regress/test_branch_and_gc.py

@@ -2,14 +2,17 @@ from __future__ import annotations
 
 import threading
 import time
+from typing import TYPE_CHECKING
 
 import pytest
 from fixtures.common_types import Lsn, TimelineId
 from fixtures.log_helper import log
-from fixtures.neon_fixtures import NeonEnv
 from fixtures.pageserver.http import TimelineCreate406
 from fixtures.utils import query_scalar, skip_in_debug_build
 
+if TYPE_CHECKING:
+    from fixtures.neon_fixtures import NeonEnv
+
 
 # Test the GC implementation when running with branching.
 # This test reproduces the issue https://github.com/neondatabase/neon/issues/707.
@@ -58,9 +61,9 @@ def test_branch_and_gc(neon_simple_env: NeonEnv):
             # disable background GC
             "gc_period": "0s",
             # small checkpoint distance to create more delta layer files
-            "checkpoint_distance": f"{1024 ** 2}",
+            "checkpoint_distance": f"{1024**2}",
             # set the target size to be large to allow the image layer to cover the whole key space
-            "compaction_target_size": f"{1024 ** 3}",
+            "compaction_target_size": f"{1024**3}",
             # tweak the default settings to allow quickly create image layers and L1 layers
             "compaction_period": "1 s",
             "compaction_threshold": "2",
@@ -134,9 +137,9 @@ def test_branch_creation_before_gc(neon_simple_env: NeonEnv):
             # disable background GC
             "gc_period": "0s",
             # small checkpoint distance to create more delta layer files
-            "checkpoint_distance": f"{1024 ** 2}",
+            "checkpoint_distance": f"{1024**2}",
             # set the target size to be large to allow the image layer to cover the whole key space
-            "compaction_target_size": f"{1024 ** 3}",
+            "compaction_target_size": f"{1024**3}",
             # tweak the default settings to allow quickly create image layers and L1 layers
             "compaction_period": "1 s",
             "compaction_threshold": "2",

test_runner/regress/test_branch_behind.py

@@ -1,12 +1,16 @@
 from __future__ import annotations
 
+from typing import TYPE_CHECKING
+
 import pytest
 from fixtures.common_types import Lsn, TimelineId
 from fixtures.log_helper import log
-from fixtures.neon_fixtures import NeonEnvBuilder
 from fixtures.pageserver.http import TimelineCreate406
 from fixtures.utils import print_gc_result, query_scalar
 
+if TYPE_CHECKING:
+    from fixtures.neon_fixtures import NeonEnvBuilder
+
 
 #
 # Create a couple of branches off the main branch, at a historical point in time.

test_runner/regress/test_branching.py

@@ -4,16 +4,11 @@ import random
 import threading
 import time
 from concurrent.futures import ThreadPoolExecutor
+from typing import TYPE_CHECKING
 
 import pytest
 from fixtures.common_types import Lsn, TimelineId
 from fixtures.log_helper import log
-from fixtures.neon_fixtures import (
-    Endpoint,
-    NeonEnv,
-    NeonEnvBuilder,
-    PgBin,
-)
 from fixtures.pageserver.http import PageserverApiException
 from fixtures.pageserver.utils import wait_until_tenant_active
 from fixtures.utils import query_scalar
@@ -21,6 +16,14 @@ from performance.test_perf_pgbench import get_scales_matrix
 from requests import RequestException
 from requests.exceptions import RetryError
 
+if TYPE_CHECKING:
+    from fixtures.neon_fixtures import (
+        Endpoint,
+        NeonEnv,
+        NeonEnvBuilder,
+        PgBin,
+    )
+
 
 # Test branch creation
 #
@@ -43,9 +46,9 @@ def test_branching_with_pgbench(
     tenant, _ = env.create_tenant(
         conf={
             "gc_period": "5 s",
-            "gc_horizon": f"{1024 ** 2}",
+            "gc_horizon": f"{1024**2}",
-            "checkpoint_distance": f"{1024 ** 2}",
+            "checkpoint_distance": f"{1024**2}",
-            "compaction_target_size": f"{1024 ** 2}",
+            "compaction_target_size": f"{1024**2}",
             # set PITR interval to be small, so we can do GC
             "pitr_interval": "5 s",
         }

test_runner/regress/test_broken_timeline.py

@@ -124,14 +124,14 @@ def test_timeline_init_break_before_checkpoint(neon_env_builder: NeonEnvBuilder)
 
     # Creating the timeline didn't finish. The other timelines on tenant should still be present and work normally.
     new_tenant_timelines = env.neon_cli.timeline_list(tenant_id)
-    assert (
+    assert new_tenant_timelines == old_tenant_timelines, (
-        new_tenant_timelines == old_tenant_timelines
+        f"Pageserver after restart should ignore non-initialized timelines for tenant {tenant_id}"
-    ), f"Pageserver after restart should ignore non-initialized timelines for tenant {tenant_id}"
+    )
 
     timeline_dirs = [d for d in timelines_dir.iterdir()]
-    assert (
+    assert timeline_dirs == initial_timeline_dirs, (
-        timeline_dirs == initial_timeline_dirs
+        "pageserver should clean its temp timeline files on timeline creation failure"
-    ), "pageserver should clean its temp timeline files on timeline creation failure"
+    )
 
 
 # The "exit" case is for a reproducer of issue 6007: an unclean shutdown where we can't do local fs cleanups
@@ -176,14 +176,14 @@ def test_timeline_init_break_before_checkpoint_recreate(
 
     # Creating the timeline didn't finish. The other timelines on tenant should still be present and work normally.
     new_tenant_timelines = env.neon_cli.timeline_list(tenant_id)
-    assert (
+    assert new_tenant_timelines == old_tenant_timelines, (
-        new_tenant_timelines == old_tenant_timelines
+        f"Pageserver after restart should ignore non-initialized timelines for tenant {tenant_id}"
-    ), f"Pageserver after restart should ignore non-initialized timelines for tenant {tenant_id}"
+    )
 
     timeline_dirs = [d for d in timelines_dir.iterdir()]
-    assert (
+    assert timeline_dirs == initial_timeline_dirs, (
-        timeline_dirs == initial_timeline_dirs
+        "pageserver should clean its temp timeline files on timeline creation failure"
-    ), "pageserver should clean its temp timeline files on timeline creation failure"
+    )
 
     # creating the branch should have worked now
     new_timeline_id = TimelineId(
@@ -211,11 +211,11 @@ def test_timeline_create_break_after_dir_creation(neon_env_builder: NeonEnvBuild
     # Creating the timeline didn't finish. The other timelines on tenant should still be present and work normally.
     # "New" timeline is not present in the list, allowing pageserver to retry the same request
     new_tenant_timelines = env.neon_cli.timeline_list(tenant_id)
-    assert (
+    assert new_tenant_timelines == old_tenant_timelines, (
-        new_tenant_timelines == old_tenant_timelines
+        f"Pageserver after restart should ignore non-initialized timelines for tenant {tenant_id}"
-    ), f"Pageserver after restart should ignore non-initialized timelines for tenant {tenant_id}"
+    )
 
     timeline_dirs = [d for d in timelines_dir.iterdir()]
-    assert (
+    assert timeline_dirs == initial_timeline_dirs, (
-        timeline_dirs == initial_timeline_dirs
+        "pageserver should clean its temp timeline files on timeline creation failure"
-    ), "pageserver should clean its temp timeline files on timeline creation failure"
+    )

test_runner/regress/test_build_info_metric.py

@@ -1,7 +1,11 @@
 from __future__ import annotations
 
+from typing import TYPE_CHECKING
+
 from fixtures.metrics import parse_metrics
-from fixtures.neon_fixtures import NeonEnvBuilder, NeonProxy
+
+if TYPE_CHECKING:
+    from fixtures.neon_fixtures import NeonEnvBuilder, NeonProxy
 
 
 def test_build_info_metric(neon_env_builder: NeonEnvBuilder, link_proxy: NeonProxy):

test_runner/regress/test_change_pageserver.py

@@ -1,11 +1,14 @@
 from __future__ import annotations
 
 import asyncio
+from typing import TYPE_CHECKING
 
 from fixtures.log_helper import log
-from fixtures.neon_fixtures import NeonEnvBuilder
 from fixtures.remote_storage import RemoteStorageKind
 
+if TYPE_CHECKING:
+    from fixtures.neon_fixtures import NeonEnvBuilder
+
 
 def test_change_pageserver(neon_env_builder: NeonEnvBuilder):
     """

test_runner/regress/test_clog_truncate.py

@@ -1,11 +1,14 @@
 from __future__ import annotations
 
 import os
+from typing import TYPE_CHECKING
 
 from fixtures.log_helper import log
-from fixtures.neon_fixtures import NeonEnvBuilder
 from fixtures.utils import query_scalar, wait_until
 
+if TYPE_CHECKING:
+    from fixtures.neon_fixtures import NeonEnvBuilder
+
 
 #
 # Test compute node start after clog truncation

test_runner/regress/test_close_fds.py

@@ -6,9 +6,12 @@ import subprocess
 import threading
 import time
 from contextlib import closing
+from typing import TYPE_CHECKING
 
 from fixtures.log_helper import log
-from fixtures.neon_fixtures import NeonEnv
+
+if TYPE_CHECKING:
+    from fixtures.neon_fixtures import NeonEnv
 
 
 def lsof_path() -> str:

test_runner/regress/test_compaction.py

@@ -177,7 +177,7 @@ def test_pageserver_gc_compaction_smoke(neon_env_builder: NeonEnvBuilder, with_b
         "compaction_period": "5s",
         # No PiTR interval and small GC horizon
         "pitr_interval": "0s",
-        "gc_horizon": f"{1024 ** 2}",
+        "gc_horizon": f"{1024**2}",
         "lsn_lease_length": "0s",
     }
 
@@ -867,7 +867,7 @@ def test_image_layer_compression(neon_env_builder: NeonEnvBuilder, enabled: bool
     )
     assert bytes_in is not None
     assert bytes_out is not None
-    log.info(f"Compression ratio: {bytes_out/bytes_in} ({bytes_out} in, {bytes_out} out)")
+    log.info(f"Compression ratio: {bytes_out / bytes_in} ({bytes_out} in, {bytes_out} out)")
 
     if enabled:
         # We are writing high compressible repetitive plain text, expect excellent compression

test_runner/regress/test_compatibility.py

@@ -7,12 +7,12 @@ import subprocess
 import tempfile
 from dataclasses import dataclass
 from pathlib import Path
+from typing import TYPE_CHECKING
 
 import fixtures.utils
 import pytest
 import toml
 from fixtures.common_types import TenantId, TimelineId
-from fixtures.compute_reconfigure import ComputeReconfigure
 from fixtures.log_helper import log
 from fixtures.neon_fixtures import (
     NeonEnv,
@@ -28,6 +28,9 @@ from fixtures.pg_version import PgVersion
 from fixtures.remote_storage import RemoteStorageKind, S3Storage, s3_storage
 from fixtures.workload import Workload
 
+if TYPE_CHECKING:
+    from fixtures.compute_reconfigure import ComputeReconfigure
+
 #
 # A test suite that help to prevent unintentionally breaking backward or forward compatibility between Neon releases.
 # - `test_create_snapshot` a script wrapped in a test that creates a data snapshot.
@@ -232,7 +235,9 @@ def test_backward_compatibility(
         else:
             raise
 
-    assert not breaking_changes_allowed, "Breaking changes are allowed by ALLOW_BACKWARD_COMPATIBILITY_BREAKAGE, but the test has passed without any breakage"
+    assert not breaking_changes_allowed, (
+        "Breaking changes are allowed by ALLOW_BACKWARD_COMPATIBILITY_BREAKAGE, but the test has passed without any breakage"
+    )
 
 
 @check_ondisk_data_compatibility_if_enabled
@@ -260,12 +265,12 @@ def test_forward_compatibility(
         # Use previous version's production binaries (pageserver, safekeeper, pg_distrib_dir, etc.).
         # But always use the current version's neon_local binary.
         # This is because we want to test the compatibility of the data format, not the compatibility of the neon_local CLI.
-        assert (
+        assert neon_env_builder.compatibility_neon_binpath is not None, (
-            neon_env_builder.compatibility_neon_binpath is not None
+            "the environment variable COMPATIBILITY_NEON_BIN is required"
-        ), "the environment variable COMPATIBILITY_NEON_BIN is required"
+        )
-        assert (
+        assert neon_env_builder.compatibility_pg_distrib_dir is not None, (
-            neon_env_builder.compatibility_pg_distrib_dir is not None
+            "the environment variable COMPATIBILITY_POSTGRES_DISTRIB_DIR is required"
-        ), "the environment variable COMPATIBILITY_POSTGRES_DISTRIB_DIR is required"
+        )
         neon_env_builder.neon_binpath = neon_env_builder.compatibility_neon_binpath
         neon_env_builder.pg_distrib_dir = neon_env_builder.compatibility_pg_distrib_dir
 
@@ -311,7 +316,9 @@ def test_forward_compatibility(
         else:
             raise
 
-    assert not breaking_changes_allowed, "Breaking changes are allowed by ALLOW_FORWARD_COMPATIBILITY_BREAKAGE, but the test has passed without any breakage"
+    assert not breaking_changes_allowed, (
+        "Breaking changes are allowed by ALLOW_FORWARD_COMPATIBILITY_BREAKAGE, but the test has passed without any breakage"
+    )
 
 
 def check_neon_works(env: NeonEnv, test_output_dir: Path, sql_dump_path: Path, repo_dir: Path):

test_runner/regress/test_compute_catalog.py

@@ -103,22 +103,22 @@ def test_compute_catalog(neon_simple_env: NeonEnv):
     objects = client.dbs_and_roles()
 
     # Assert that 'cloud_admin' role exists in the 'roles' list
-    assert any(
+    assert any(role["name"] == "cloud_admin" for role in objects["roles"]), (
-        role["name"] == "cloud_admin" for role in objects["roles"]
+        "The 'cloud_admin' role is missing"
-    ), "The 'cloud_admin' role is missing"
+    )
 
     # Assert that 'postgres' database exists in the 'databases' list
-    assert any(
+    assert any(db["name"] == "postgres" for db in objects["databases"]), (
-        db["name"] == "postgres" for db in objects["databases"]
+        "The 'postgres' database is missing"
-    ), "The 'postgres' database is missing"
+    )
 
     # Check other databases
     for test_db in TEST_DB_NAMES:
         db = next((db for db in objects["databases"] if db["name"] == test_db["name"]), None)
         assert db is not None, f"The '{test_db['name']}' database is missing"
-        assert (
+        assert db["owner"] == test_db["owner"], (
-            db["owner"] == test_db["owner"]
+            f"The '{test_db['name']}' database has incorrect owner"
-        ), f"The '{test_db['name']}' database has incorrect owner"
+        )
 
         ddl = client.database_schema(database=test_db["name"])
 
@@ -135,9 +135,9 @@ def test_compute_catalog(neon_simple_env: NeonEnv):
         client.database_schema(database="nonexistentdb")
         raise AssertionError("Expected HTTPError was not raised")
     except requests.exceptions.HTTPError as e:
-        assert (
+        assert e.response.status_code == 404, (
-            e.response.status_code == 404
+            f"Expected 404 status code, but got {e.response.status_code}"
-        ), f"Expected 404 status code, but got {e.response.status_code}"
+        )
 
 
 def test_compute_create_drop_dbs_and_roles(neon_simple_env: NeonEnv):

test_runner/regress/test_compute_metrics.py

@@ -13,21 +13,21 @@ import _jsonnet
 import pytest
 import requests
 import yaml
-from fixtures.endpoint.http import EndpointHttpClient
 from fixtures.log_helper import log
 from fixtures.metrics import parse_metrics
 from fixtures.paths import BASE_DIR, COMPUTE_CONFIG_DIR
 from fixtures.utils import wait_until
-from prometheus_client.samples import Sample
 
 if TYPE_CHECKING:
     from collections.abc import Callable
     from types import TracebackType
     from typing import Self, TypedDict
 
+    from fixtures.endpoint.http import EndpointHttpClient
     from fixtures.neon_fixtures import NeonEnv
     from fixtures.pg_version import PgVersion
     from fixtures.port_distributor import PortDistributor
+    from prometheus_client.samples import Sample
 
     class Metric(TypedDict):
         metric_name: str

test_runner/regress/test_compute_migrations.py

@@ -1,6 +1,5 @@
 from __future__ import annotations
 
-from pathlib import Path
 from typing import TYPE_CHECKING, cast
 
 import pytest
@@ -9,6 +8,8 @@ from fixtures.metrics import parse_metrics
 from fixtures.utils import wait_until
 
 if TYPE_CHECKING:
+    from pathlib import Path
+
     from fixtures.neon_fixtures import NeonEnv
 
 

test_runner/regress/test_compute_reconfigure.py

@@ -1,8 +1,12 @@
 from __future__ import annotations
 
-from fixtures.neon_fixtures import NeonEnv
+from typing import TYPE_CHECKING
+
 from fixtures.utils import wait_until
 
+if TYPE_CHECKING:
+    from fixtures.neon_fixtures import NeonEnv
+
 
 def test_compute_reconfigure(neon_simple_env: NeonEnv):
     """

test_runner/regress/test_config.py

@@ -2,8 +2,10 @@ from __future__ import annotations
 
 import os
 from contextlib import closing
+from typing import TYPE_CHECKING
 
-from fixtures.neon_fixtures import NeonEnv, NeonEnvBuilder
+if TYPE_CHECKING:
+    from fixtures.neon_fixtures import NeonEnv, NeonEnvBuilder
 
 
 #

test_runner/regress/test_createuser.py

@@ -1,8 +1,12 @@
 from __future__ import annotations
 
-from fixtures.neon_fixtures import NeonEnv
+from typing import TYPE_CHECKING
+
 from fixtures.utils import query_scalar
 
+if TYPE_CHECKING:
+    from fixtures.neon_fixtures import NeonEnv
+
 
 #
 # Test CREATE USER to check shared catalog restore

test_runner/regress/test_ddl_forwarding.py

@@ -1,21 +1,21 @@
 from __future__ import annotations
 
-from types import TracebackType
 from typing import TYPE_CHECKING
 
 import psycopg2
 import pytest
 from fixtures.log_helper import log
-from fixtures.neon_fixtures import NeonEnv, VanillaPostgres
 from psycopg2.errors import UndefinedObject
-from pytest_httpserver import HTTPServer
-from werkzeug.wrappers.request import Request
 from werkzeug.wrappers.response import Response
 
 if TYPE_CHECKING:
+    from types import TracebackType
     from typing import Any, Self
 
     from fixtures.httpserver import ListenAddress
+    from fixtures.neon_fixtures import NeonEnv, VanillaPostgres
+    from pytest_httpserver import HTTPServer
+    from werkzeug.wrappers.request import Request
 
 
 def handle_db(dbs, roles, operation):

test_runner/regress/test_disk_usage_eviction.py

@@ -3,7 +3,6 @@ from __future__ import annotations
 import enum
 import time
 from collections import Counter
-from collections.abc import Iterable
 from dataclasses import dataclass
 from enum import StrEnum
 from typing import TYPE_CHECKING
@@ -18,14 +17,16 @@ from fixtures.neon_fixtures import (
     PgBin,
     wait_for_last_flush_lsn,
 )
-from fixtures.pageserver.http import PageserverHttpClient
 from fixtures.pageserver.utils import wait_for_upload_queue_empty
 from fixtures.remote_storage import RemoteStorageKind
 from fixtures.utils import human_bytes, wait_until
 
 if TYPE_CHECKING:
+    from collections.abc import Iterable
     from typing import Any
 
+    from fixtures.pageserver.http import PageserverHttpClient
+
 
 GLOBAL_LRU_LOG_LINE = "tenant_min_resident_size-respecting LRU would not relieve pressure, evicting more following global LRU policy"
 
@@ -323,9 +324,9 @@ def finish_tenant_creation(
 
     layers = pageserver_http.layer_map_info(tenant_id, timeline_id)
     # log.info(f"{layers}")
-    assert (
+    assert len(layers.historic_layers) >= min_expected_layers, (
-        len(layers.historic_layers) >= min_expected_layers
+        "evictions happen at layer granularity, but we often assert at byte-granularity"
-    ), "evictions happen at layer granularity, but we often assert at byte-granularity"
+    )
 
     return pgbench_init_lsn
 
@@ -421,9 +422,9 @@ def test_pageserver_evicts_until_pressure_is_relieved(
 
     assert 0 <= actual_change, "nothing can load layers during this test"
     assert actual_change >= target, "must evict more than half"
-    assert (
+    assert response["Finished"]["assumed"]["projected_after"]["freed_bytes"] >= actual_change, (
-        response["Finished"]["assumed"]["projected_after"]["freed_bytes"] >= actual_change
+        "report accurately evicted bytes"
-    ), "report accurately evicted bytes"
+    )
     assert response["Finished"]["assumed"]["failed"]["count"] == 0, "zero failures expected"
 
 
@@ -448,18 +449,18 @@ def test_pageserver_respects_overridden_resident_size(
     large_tenant = max(du_by_timeline, key=du_by_timeline.__getitem__)
     small_tenant = min(du_by_timeline, key=du_by_timeline.__getitem__)
     assert du_by_timeline[large_tenant] > du_by_timeline[small_tenant]
-    assert (
+    assert du_by_timeline[large_tenant] - du_by_timeline[small_tenant] > 5 * env.layer_size, (
-        du_by_timeline[large_tenant] - du_by_timeline[small_tenant] > 5 * env.layer_size
+        "ensure this test will do more than 1 eviction"
-    ), "ensure this test will do more than 1 eviction"
+    )
 
     # Give the larger tenant a haircut while preventing the smaller tenant from getting one.
     # To prevent the smaller from getting a haircut, we set min_resident_size to its current size.
     # To ensure the larger tenant is getting a haircut, any non-zero `target` will do.
     min_resident_size = du_by_timeline[small_tenant]
     target = 1
-    assert (
+    assert du_by_timeline[large_tenant] > min_resident_size, (
-        du_by_timeline[large_tenant] > min_resident_size
+        "ensure the larger tenant will get a haircut"
-    ), "ensure the larger tenant will get a haircut"
+    )
     env.neon_env.storage_controller.pageserver_api().update_tenant_config(
         small_tenant[0], {"min_resident_size_override": min_resident_size}
     )
@@ -490,17 +491,17 @@ def test_pageserver_respects_overridden_resident_size(
     actual_change = total_on_disk - later_total_on_disk
     assert 0 <= actual_change, "nothing can load layers during this test"
     assert actual_change >= target, "eviction must always evict more than target"
-    assert (
+    assert response["Finished"]["assumed"]["projected_after"]["freed_bytes"] >= actual_change, (
-        response["Finished"]["assumed"]["projected_after"]["freed_bytes"] >= actual_change
+        "report accurately evicted bytes"
-    ), "report accurately evicted bytes"
+    )
     assert response["Finished"]["assumed"]["failed"]["count"] == 0, "zero failures expected"
 
-    assert (
+    assert later_du_by_timeline[small_tenant] == du_by_timeline[small_tenant], (
-        later_du_by_timeline[small_tenant] == du_by_timeline[small_tenant]
+        "small tenant sees no haircut"
-    ), "small tenant sees no haircut"
+    )
-    assert (
+    assert later_du_by_timeline[large_tenant] < du_by_timeline[large_tenant], (
-        later_du_by_timeline[large_tenant] < du_by_timeline[large_tenant]
+        "large tenant gets a haircut"
-    ), "large tenant gets a haircut"
+    )
     assert du_by_timeline[large_tenant] - later_du_by_timeline[large_tenant] >= target
 
 
@@ -579,9 +580,9 @@ def test_partial_evict_tenant(eviction_env: EvictionEnv, order: EvictionOrder):
 
     later_du_by_timeline = env.du_by_timeline(env.pageserver)
     for tenant, later_tenant_usage in later_du_by_timeline.items():
-        assert (
+        assert later_tenant_usage < du_by_timeline[tenant], (
-            later_tenant_usage < du_by_timeline[tenant]
+            "all tenants should have lost some layers"
-        ), "all tenants should have lost some layers"
+        )
 
     # with relative order what matters is the amount of layers, with a
     # fudge factor of whether the eviction bothers tenants with highest
@@ -665,9 +666,9 @@ def test_fast_growing_tenant(neon_env_builder: NeonEnvBuilder, pg_bin: PgBin, or
         ratio = after / originally
         ratios.append(ratio)
 
-    assert (
+    assert len(ratios) == 4, (
-        len(ratios) == 4
+        "rest of the assertions expect 3 + 1 timelines, ratios, scales, all in order"
-    ), "rest of the assertions expect 3 + 1 timelines, ratios, scales, all in order"
+    )
     log.info(f"{ratios}")
 
     if order == EvictionOrder.RELATIVE_ORDER_EQUAL:
@@ -829,9 +830,9 @@ def test_statvfs_pressure_min_avail_bytes(eviction_env: EvictionEnv):
 
     def more_than_min_avail_bytes_freed():
         post_eviction_total_size, _, _ = env.timelines_du(env.pageserver)
-        assert (
+        assert total_size - post_eviction_total_size >= min_avail_bytes, (
-            total_size - post_eviction_total_size >= min_avail_bytes
+            f"we requested at least {min_avail_bytes} worth of free space"
-        ), f"we requested at least {min_avail_bytes} worth of free space"
+        )
 
     wait_until(more_than_min_avail_bytes_freed, timeout=5)
 
@@ -878,6 +879,6 @@ def test_secondary_mode_eviction(eviction_env_ha: EvictionEnv):
 
     post_eviction_total_size, _, _ = env.timelines_du(ps_secondary)
 
-    assert (
+    assert total_size - post_eviction_total_size >= evict_bytes, (
-        total_size - post_eviction_total_size >= evict_bytes
+        "we requested at least evict_bytes worth of free space"
-    ), "we requested at least evict_bytes worth of free space"
+    )

test_runner/regress/test_download_extensions.py

@@ -3,17 +3,16 @@ from __future__ import annotations
 import os
 import shutil
 import tarfile
-from pathlib import Path
 from typing import TYPE_CHECKING
 
 import pytest
 import zstandard
 from fixtures.log_helper import log
 from fixtures.metrics import parse_metrics
-from pytest_httpserver import HTTPServer
 from werkzeug.wrappers.response import Response
 
 if TYPE_CHECKING:
+    from pathlib import Path
     from typing import Any
 
     from fixtures.httpserver import ListenAddress
@@ -21,6 +20,7 @@ if TYPE_CHECKING:
         NeonEnvBuilder,
     )
     from fixtures.pg_version import PgVersion
+    from pytest_httpserver import HTTPServer
     from werkzeug.wrappers.request import Request
 
 

test_runner/regress/test_endpoint_crash.py

@@ -1,10 +1,14 @@
 from __future__ import annotations
 
+from typing import TYPE_CHECKING
+
 import pytest
-from fixtures.neon_fixtures import NeonEnvBuilder
 from fixtures.pg_version import PgVersion
 from fixtures.utils import WITH_SANITIZERS, run_only_on_postgres
 
+if TYPE_CHECKING:
+    from fixtures.neon_fixtures import NeonEnvBuilder
+
 
 @pytest.mark.parametrize(
     "sql_func",

test_runner/regress/test_explain_with_lfc_stats.py

@@ -1,12 +1,15 @@
 from __future__ import annotations
 
 from pathlib import Path
+from typing import TYPE_CHECKING
 
 import pytest
 from fixtures.log_helper import log
-from fixtures.neon_fixtures import NeonEnv
 from fixtures.utils import USE_LFC
 
+if TYPE_CHECKING:
+    from fixtures.neon_fixtures import NeonEnv
+
 
 @pytest.mark.skipif(not USE_LFC, reason="LFC is disabled, skipping")
 def test_explain_with_lfc_stats(neon_simple_env: NeonEnv):

test_runner/regress/test_fsm_truncate.py

@@ -1,6 +1,9 @@
 from __future__ import annotations
 
-from fixtures.neon_fixtures import NeonEnvBuilder
+from typing import TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from fixtures.neon_fixtures import NeonEnvBuilder
 
 
 def test_fsm_truncate(neon_env_builder: NeonEnvBuilder):

test_runner/regress/test_fullbackup.py

@@ -1,7 +1,7 @@
 from __future__ import annotations
 
 import os
-from pathlib import Path
+from typing import TYPE_CHECKING
 
 from fixtures.common_types import Lsn
 from fixtures.log_helper import log
@@ -10,9 +10,13 @@ from fixtures.neon_fixtures import (
     PgBin,
     VanillaPostgres,
 )
-from fixtures.port_distributor import PortDistributor
 from fixtures.utils import query_scalar, subprocess_capture
 
+if TYPE_CHECKING:
+    from pathlib import Path
+
+    from fixtures.port_distributor import PortDistributor
+
 num_rows = 1000
 
 

test_runner/regress/test_gc_aggressive.py

@@ -3,8 +3,8 @@ from __future__ import annotations
 import asyncio
 import concurrent.futures
 import random
+from typing import TYPE_CHECKING
 
-from fixtures.common_types import TimelineId
 from fixtures.log_helper import log
 from fixtures.neon_fixtures import (
     Endpoint,
@@ -14,6 +14,9 @@ from fixtures.neon_fixtures import (
 )
 from fixtures.remote_storage import RemoteStorageKind
 
+if TYPE_CHECKING:
+    from fixtures.common_types import TimelineId
+
 # Test configuration
 #
 # Create a table with {NUM_ROWS} rows, and perform {UPDATES_TO_PERFORM} random

test_runner/regress/test_import.py

@@ -6,17 +6,11 @@ import re
 import shutil
 import tarfile
 from contextlib import closing
-from pathlib import Path
+from typing import TYPE_CHECKING
 
 import pytest
 from fixtures.common_types import Lsn, TenantId, TimelineId
 from fixtures.log_helper import log
-from fixtures.neon_fixtures import (
-    Endpoint,
-    NeonEnv,
-    NeonEnvBuilder,
-    PgBin,
-)
 from fixtures.pageserver.utils import (
     timeline_delete_wait_completed,
     wait_for_last_record_lsn,
@@ -24,6 +18,16 @@ from fixtures.pageserver.utils import (
 from fixtures.remote_storage import RemoteStorageKind
 from fixtures.utils import assert_pageserver_backups_equal, subprocess_capture
 
+if TYPE_CHECKING:
+    from pathlib import Path
+
+    from fixtures.neon_fixtures import (
+        Endpoint,
+        NeonEnv,
+        NeonEnvBuilder,
+        PgBin,
+    )
+
 
 def test_import_from_vanilla(test_output_dir, pg_bin, vanilla_pg, neon_env_builder):
     # Put data in vanilla pg
@@ -179,7 +183,7 @@ def test_import_from_pageserver_multisegment(
     logical_size = env.pageserver.http_client().timeline_detail(env.initial_tenant, timeline)[
         "current_logical_size"
     ]
-    log.info(f"timeline logical size = {logical_size / (1024 ** 2)}MB")
+    log.info(f"timeline logical size = {logical_size / (1024**2)}MB")
     assert logical_size > 1024**3  # = 1GB
 
     tar_output_file = _import(num_rows, lsn, env, pg_bin, timeline, test_output_dir)

test_runner/regress/test_import_pgdata.py

@@ -287,9 +287,9 @@ def test_pgdata_import_smoke(
         shard_ps = env.get_pageserver(shard["node_id"])
         result = shard_ps.timeline_scan_no_disposable_keys(shard["shard_id"], timeline_id)
         assert result.tally.disposable_count == 0
-        assert (
+        assert result.tally.not_disposable_count > 0, (
-            result.tally.not_disposable_count > 0
+            "sanity check, each shard should have some data"
-        ), "sanity check, each shard should have some data"
+        )
 
     #
     # validate that we can write

test_runner/regress/test_ingestion_layer_size.py

@@ -1,13 +1,17 @@
 from __future__ import annotations
 
-from collections.abc import Iterable
 from dataclasses import dataclass
+from typing import TYPE_CHECKING
 
 from fixtures.log_helper import log
 from fixtures.neon_fixtures import NeonEnvBuilder, wait_for_last_flush_lsn
-from fixtures.pageserver.http import HistoricLayerInfo, LayerMapInfo
 from fixtures.utils import human_bytes, skip_in_debug_build
 
+if TYPE_CHECKING:
+    from collections.abc import Iterable
+
+    from fixtures.pageserver.http import HistoricLayerInfo, LayerMapInfo
+
 
 @skip_in_debug_build("debug run is unnecessarily slow")
 def test_ingesting_large_batches_of_images(neon_env_builder: NeonEnvBuilder):
@@ -27,9 +31,9 @@ def test_ingesting_large_batches_of_images(neon_env_builder: NeonEnvBuilder):
     # bucket lower limits
     buckets = [0, minimum_initdb_size, minimum_good_layer_size, minimum_too_large_layer_size]
 
-    assert (
+    assert minimum_initdb_size < minimum_good_layer_size, (
-        minimum_initdb_size < minimum_good_layer_size
+        "keep checkpoint_distance higher than the initdb size (find it by experimenting)"
-    ), "keep checkpoint_distance higher than the initdb size (find it by experimenting)"
+    )
 
     env = neon_env_builder.init_start(
         initial_tenant_conf={
@@ -57,9 +61,9 @@ def test_ingesting_large_batches_of_images(neon_env_builder: NeonEnvBuilder):
         assert size is not None
         assert isinstance(size[0], int)
         log.info(f"gin index size: {human_bytes(size[0])}")
-        assert (
+        assert size[0] > checkpoint_distance * 3, (
-            size[0] > checkpoint_distance * 3
+            f"gin index is not large enough: {human_bytes(size[0])}"
-        ), f"gin index is not large enough: {human_bytes(size[0])}"
+        )
         wait_for_last_flush_lsn(env, ep, env.initial_tenant, env.initial_timeline)
 
     ps_http = env.pageserver.http_client()
@@ -91,13 +95,13 @@ def test_ingesting_large_batches_of_images(neon_env_builder: NeonEnvBuilder):
     log.info("non-cumulative layer size distribution after compaction:")
     print_layer_size_histogram(post_compact)
 
-    assert (
+    assert post_ingest.counts[3] == 0, (
-        post_ingest.counts[3] == 0
+        f"there should be no layers larger than 2*checkpoint_distance ({human_bytes(2 * checkpoint_distance)})"
-    ), f"there should be no layers larger than 2*checkpoint_distance ({human_bytes(2*checkpoint_distance)})"
+    )
     assert post_ingest.counts[1] == 1, "expect one smaller layer for initdb"
-    assert (
+    assert post_ingest.counts[0] <= 1, (
-        post_ingest.counts[0] <= 1
+        "expect at most one tiny layer from shutting down the endpoint"
-    ), "expect at most one tiny layer from shutting down the endpoint"
+    )
 
     # just make sure we don't have trouble splitting the layers apart
     assert post_compact.counts[3] == 0

test_runner/regress/test_large_schema.py

@@ -2,9 +2,12 @@ from __future__ import annotations
 
 import os
 import time
+from typing import TYPE_CHECKING
 
 from fixtures.log_helper import log
-from fixtures.neon_fixtures import NeonEnvBuilder
+
+if TYPE_CHECKING:
+    from fixtures.neon_fixtures import NeonEnvBuilder
 
 
 # This test creates large number of tables which cause large catalog.

test_runner/regress/test_layer_eviction.py

@@ -59,70 +59,72 @@ def test_basic_eviction(neon_env_builder: NeonEnvBuilder):
         (parse_layer_file_name(path.name), path)
         for path in env.pageserver.list_layers(tenant_id, timeline_id)
     )
-    assert (
+    assert len(initial_local_layers) > 1, (
-        len(initial_local_layers) > 1
+        f"Should create multiple layers for timeline, but got {initial_local_layers}"
-    ), f"Should create multiple layers for timeline, but got {initial_local_layers}"
+    )
 
     # Compare layer map dump with the local layers, ensure everything's present locally and matches
     initial_layer_map_info = client.layer_map_info(tenant_id=tenant_id, timeline_id=timeline_id)
-    assert (
+    assert not initial_layer_map_info.in_memory_layers, (
-        not initial_layer_map_info.in_memory_layers
+        "Should have no in memory layers after flushing"
-    ), "Should have no in memory layers after flushing"
+    )
-    assert len(initial_local_layers) == len(
+    assert len(initial_local_layers) == len(initial_layer_map_info.historic_layers), (
-        initial_layer_map_info.historic_layers
+        "Should have the same layers in memory and on disk"
-    ), "Should have the same layers in memory and on disk"
+    )
 
     for returned_layer in initial_layer_map_info.historic_layers:
-        assert (
+        assert returned_layer.kind == "Delta", (
-            returned_layer.kind == "Delta"
+            f"Did not create and expect image layers, but got {returned_layer}"
-        ), f"Did not create and expect image layers, but got {returned_layer}"
+        )
-        assert (
+        assert not returned_layer.remote, (
-            not returned_layer.remote
+            f"All created layers should be present locally, but got {returned_layer}"
-        ), f"All created layers should be present locally, but got {returned_layer}"
+        )
 
         returned_layer_name = parse_layer_file_name(returned_layer.layer_file_name)
-        assert (
+        assert returned_layer_name in initial_local_layers, (
-            returned_layer_name in initial_local_layers
+            f"Did not find returned layer {returned_layer_name} in local layers {list(initial_local_layers.keys())}"
-        ), f"Did not find returned layer {returned_layer_name} in local layers {list(initial_local_layers.keys())}"
+        )
 
         local_layer_path = (
             env.pageserver.timeline_dir(tenant_id, timeline_id)
             / initial_local_layers[returned_layer_name]
         )
-        assert (
+        assert returned_layer.layer_file_size == local_layer_path.stat().st_size, (
-            returned_layer.layer_file_size == local_layer_path.stat().st_size
+            f"Returned layer {returned_layer} has a different file size than local layer {local_layer_path}"
-        ), f"Returned layer {returned_layer} has a different file size than local layer {local_layer_path}"
+        )
 
     # Detach all layers, ensre they are not in the local FS, but are still dumped as part of the layer map
     for local_layer_name, local_layer_path in initial_local_layers.items():
         client.evict_layer(
             tenant_id=tenant_id, timeline_id=timeline_id, layer_name=local_layer_path.name
         )
-        assert not env.pageserver.layer_exists(
+        assert not env.pageserver.layer_exists(tenant_id, timeline_id, local_layer_name), (
-            tenant_id, timeline_id, local_layer_name
+            f"Did not expect to find {local_layer_name} layer after evicting"
-        ), f"Did not expect to find {local_layer_name} layer after evicting"
+        )
 
     empty_layers = env.pageserver.list_layers(tenant_id, timeline_id)
-    assert not empty_layers, f"After evicting all layers, timeline {tenant_id}/{timeline_id} should have no layers locally, but got: {empty_layers}"
+    assert not empty_layers, (
+        f"After evicting all layers, timeline {tenant_id}/{timeline_id} should have no layers locally, but got: {empty_layers}"
+    )
 
     evicted_layer_map_info = client.layer_map_info(tenant_id=tenant_id, timeline_id=timeline_id)
-    assert (
+    assert not evicted_layer_map_info.in_memory_layers, (
-        not evicted_layer_map_info.in_memory_layers
+        "Should have no in memory layers after flushing and evicting"
-    ), "Should have no in memory layers after flushing and evicting"
+    )
-    assert len(initial_local_layers) == len(
+    assert len(initial_local_layers) == len(evicted_layer_map_info.historic_layers), (
-        evicted_layer_map_info.historic_layers
+        "Should have the same layers in memory and on disk initially"
-    ), "Should have the same layers in memory and on disk initially"
+    )
     for returned_layer in evicted_layer_map_info.historic_layers:
-        assert (
+        assert returned_layer.kind == "Delta", (
-            returned_layer.kind == "Delta"
+            f"Did not create and expect image layers, but got {returned_layer}"
-        ), f"Did not create and expect image layers, but got {returned_layer}"
+        )
-        assert (
+        assert returned_layer.remote, (
-            returned_layer.remote
+            f"All layers should be evicted and not present locally, but got {returned_layer}"
-        ), f"All layers should be evicted and not present locally, but got {returned_layer}"
+        )
         returned_layer_name = parse_layer_file_name(returned_layer.layer_file_name)
-        assert (
+        assert returned_layer_name in initial_local_layers, (
-            returned_layer_name in initial_local_layers
+            f"Did not find returned layer {returned_layer} in local layers {initial_local_layers}"
-        ), f"Did not find returned layer {returned_layer} in local layers {initial_local_layers}"
+        )
 
     # redownload all evicted layers and ensure the initial state is restored
     for local_layer_name, _local_layer_path in initial_local_layers.items():
@@ -142,15 +144,15 @@ def test_basic_eviction(neon_env_builder: NeonEnvBuilder):
         (parse_layer_file_name(path.name), path)
         for path in env.pageserver.list_layers(tenant_id, timeline_id)
     )
-    assert (
+    assert redownloaded_layers == initial_local_layers, (
-        redownloaded_layers == initial_local_layers
+        "Should have the same layers locally after redownloading the evicted layers"
-    ), "Should have the same layers locally after redownloading the evicted layers"
+    )
     redownloaded_layer_map_info = client.layer_map_info(
         tenant_id=tenant_id, timeline_id=timeline_id
     )
-    assert (
+    assert redownloaded_layer_map_info == initial_layer_map_info, (
-        redownloaded_layer_map_info == initial_layer_map_info
+        "Should have the same layer map after redownloading the evicted layers"
-    ), "Should have the same layer map after redownloading the evicted layers"
+    )
 
 
 def test_gc_of_remote_layers(neon_env_builder: NeonEnvBuilder):
@@ -266,9 +268,9 @@ def test_gc_of_remote_layers(neon_env_builder: NeonEnvBuilder):
         resident_physical_size_metric = ps_http.get_timeline_metric(
             tenant_id, timeline_id, "pageserver_resident_physical_size"
         )
-        assert (
+        assert resident_physical_size_metric == 0, (
-            resident_physical_size_metric == 0
+            "ensure that resident_physical_size metric is zero"
-        ), "ensure that resident_physical_size metric is zero"
+        )
         assert resident_physical_size_metric == sum(
             layer.layer_file_size for layer in info.historic_layers if not layer.remote
         ), "ensure that resident_physical_size metric corresponds to layer map dump"

test_runner/regress/test_layer_writers_fail.py

@@ -13,9 +13,9 @@ def test_image_layer_writer_fail_before_finish(neon_simple_env: NeonEnv):
     tenant_id, timeline_id = env.create_tenant(
         conf={
             # small checkpoint distance to create more delta layer files
-            "checkpoint_distance": f"{1024 ** 2}",
+            "checkpoint_distance": f"{1024**2}",
             # set the target size to be large to allow the image layer to cover the whole key space
-            "compaction_target_size": f"{1024 ** 3}",
+            "compaction_target_size": f"{1024**3}",
             # tweak the default settings to allow quickly create image layers and L1 layers
             "compaction_period": "1 s",
             "compaction_threshold": "2",
@@ -44,9 +44,9 @@ def test_image_layer_writer_fail_before_finish(neon_simple_env: NeonEnv):
         )
     )
 
-    assert (
+    assert len(new_temp_layer_files) == 0, (
-        len(new_temp_layer_files) == 0
+        "pageserver should clean its temporary new image layer files on failure"
-    ), "pageserver should clean its temporary new image layer files on failure"
+    )
 
 
 @pytest.mark.skip("See https://github.com/neondatabase/neon/issues/2703")
@@ -57,9 +57,9 @@ def test_delta_layer_writer_fail_before_finish(neon_simple_env: NeonEnv):
     tenant_id, timeline_id = env.create_tenant(
         conf={
             # small checkpoint distance to create more delta layer files
-            "checkpoint_distance": f"{1024 ** 2}",
+            "checkpoint_distance": f"{1024**2}",
             # set the target size to be large to allow the image layer to cover the whole key space
-            "compaction_target_size": f"{1024 ** 3}",
+            "compaction_target_size": f"{1024**3}",
             # tweak the default settings to allow quickly create image layers and L1 layers
             "compaction_period": "1 s",
             "compaction_threshold": "2",
@@ -90,6 +90,6 @@ def test_delta_layer_writer_fail_before_finish(neon_simple_env: NeonEnv):
         )
     )
 
-    assert (
+    assert len(new_temp_layer_files) == 0, (
-        len(new_temp_layer_files) == 0
+        "pageserver should clean its temporary new delta layer files on failure"
-    ), "pageserver should clean its temporary new delta layer files on failure"
+    )

test_runner/regress/test_layers_from_future.py

@@ -127,9 +127,9 @@ def test_issue_5878(neon_env_builder: NeonEnvBuilder, attach_mode: str):
 
     ip = get_index_part()
     assert len(ip.layer_metadata.keys())
-    assert (
+    assert ip.disk_consistent_lsn < last_record_lsn, (
-        ip.disk_consistent_lsn < last_record_lsn
+        "sanity check for what above loop is supposed to do"
-    ), "sanity check for what above loop is supposed to do"
+    )
 
     # create the image layer from the future
     env.storage_controller.pageserver_api().update_tenant_config(
@@ -233,9 +233,9 @@ def test_issue_5878(neon_env_builder: NeonEnvBuilder, attach_mode: str):
     start = time.monotonic()
     while True:
         post_stat = future_layer_path.stat()
-        assert (
+        assert pre_stat.st_mtime == post_stat.st_mtime, (
-            pre_stat.st_mtime == post_stat.st_mtime
+            "observed PUT overtake the stucked DELETE => bug isn't fixed yet"
-        ), "observed PUT overtake the stucked DELETE => bug isn't fixed yet"
+        )
         if time.monotonic() - start > max_race_opportunity_window:
             log.info(
                 "a correct implementation would never let the later PUT overtake the earlier DELETE"

test_runner/regress/test_lfc_prefetch.py

@@ -1,12 +1,15 @@
 from __future__ import annotations
 
 import time
+from typing import TYPE_CHECKING
 
 import pytest
 from fixtures.log_helper import log
-from fixtures.neon_fixtures import NeonEnv
 from fixtures.utils import USE_LFC
 
+if TYPE_CHECKING:
+    from fixtures.neon_fixtures import NeonEnv
+
 
 @pytest.mark.timeout(600)
 @pytest.mark.skipif(not USE_LFC, reason="LFC is disabled, skipping")

test_runner/regress/test_lfc_resize.py

@@ -5,12 +5,15 @@ import re
 import subprocess
 import threading
 import time
+from typing import TYPE_CHECKING
 
 import pytest
 from fixtures.log_helper import log
-from fixtures.neon_fixtures import NeonEnv, PgBin
 from fixtures.utils import USE_LFC
 
+if TYPE_CHECKING:
+    from fixtures.neon_fixtures import NeonEnv, PgBin
+
 
 @pytest.mark.timeout(600)
 @pytest.mark.skipif(not USE_LFC, reason="LFC is disabled, skipping")

test_runner/regress/test_lfc_working_set_approximation.py

@@ -2,12 +2,15 @@ from __future__ import annotations
 
 import time
 from pathlib import Path
+from typing import TYPE_CHECKING
 
 import pytest
 from fixtures.log_helper import log
-from fixtures.neon_fixtures import NeonEnv
 from fixtures.utils import USE_LFC, query_scalar
 
+if TYPE_CHECKING:
+    from fixtures.neon_fixtures import NeonEnv
+
 
 @pytest.mark.skipif(not USE_LFC, reason="LFC is disabled, skipping")
 def test_lfc_working_set_approximation(neon_simple_env: NeonEnv):