#!/usr/bin/env python3
"""Validate Phase 5 fragment/geometry semantics in local Chromium.
Run with:
uv run --project moli-benchmark \
python scripts/layout-phase5-chromium-differential.py
The paired Rust corpus is `phase5_output_contract.rs`. This script is the
browser-semantics oracle; Phase 6 will separately expose the same Moli
answers through JS and CDP.
"""
from __future__ import annotations
import argparse
import asyncio
import base64
import json
import os
import socket
import subprocess
import tempfile
import time
import urllib.parse
from dataclasses import dataclass
from pathlib import Path
from typing import Any
from moli_benchmark.raw_cdp import RawCdpClient, connect_raw_cdp
ROOT = Path(__file__).resolve().parents[1]
FONT_PATH = ROOT / "moli-layout" / "tests" / "fixtures" / "moli-ahem.ttf"
DEFAULT_CHROMIUM = Path(
os.environ.get(
"CHROMIUM_BINARY",
str(Path.home() / "chromium" / "src" / "out" / "Default" / "chrome"),
)
).expanduser()
TOLERANCE = 0.05
@dataclass(frozen=True)
class Case:
name: str
width: int
height: int
html: str
expression: str
box_model_ids: tuple[str, ...] = ()
def fixture_cases() -> tuple[Case, ...]:
font = base64.b64encode(FONT_PATH.read_bytes()).decode("ascii")
fixed_font = (
"@font-face{font-family:MoliAhem;"
f"src:url(data:font/ttf;base64,{font}) format('truetype')}}"
)
rect_helper = "const rect=v=>[v.x,v.y,v.width,v.height];"
return (
Case(
"physical-box-model",
320,
240,
"""""",
f"""(() => {{{rect_helper}
const target=document.getElementById('target');
return {{clientRects:Array.from(target.getClientRects(),rect)}};
}})()""",
("target",),
),
Case(
"utf16-inline-range",
320,
240,
f"""ab😀cd
""",
f"""(async () => {{await document.fonts.ready;{rect_helper}
const target=document.getElementById('target');const text=target.firstChild;
const all=document.createRange();all.selectNodeContents(target);
const emoji=document.createRange();emoji.setStart(text,2);emoji.setEnd(text,4);
return {{element:Array.from(target.getClientRects(),rect),
all:Array.from(all.getClientRects(),rect),emoji:Array.from(emoji.getClientRects(),rect),
utf16Length:text.length}};
}})()""",
),
Case(
"nested-scroll-clip-hit-test",
320,
240,
"""""",
f"""(() => {{{rect_helper}
const scroller=document.getElementById('scroller');scroller.scrollLeft=40;scroller.scrollTop=30;
return {{scroller:rect(scroller.getBoundingClientRect()),
wide:rect(document.getElementById('wide').getBoundingClientRect()),
scroll:[scroller.scrollLeft,scroller.scrollTop,scroller.scrollWidth,scroller.scrollHeight,
scroller.clientWidth,scroller.clientHeight],hits:[document.elementFromPoint(10,10).id,
document.elementFromPoint(150,10).id]}};
}})()""",
),
Case(
"transform-and-paint-order-hit-test",
320,
240,
"""""",
f"""(() => {{{rect_helper}
return {{under:rect(document.getElementById('under').getBoundingClientRect()),
over:rect(document.getElementById('over').getBoundingClientRect()),
hit:document.elementFromPoint(40,40).id}};
}})()""",
("over",),
),
Case(
"viewport-fixed-root-scroll",
320,
240,
"""""",
f"""(() => {{{rect_helper}
const fixed=document.getElementById('fixed');const before=rect(fixed.getBoundingClientRect());
scrollTo(0,50);return {{before,fixed:rect(fixed.getBoundingClientRect()),
flow:rect(document.getElementById('flow').getBoundingClientRect()),scroll:[scrollX,scrollY]}};
}})()""",
),
)
EXPECTED: dict[str, dict[str, Any]] = {
"physical-box-model": {
"clientRects": [[3, 3, 114, 74]],
"boxModels": {
"target": {
"content": [10, 10, 110, 10, 110, 70, 10, 70],
"padding": [5, 5, 115, 5, 115, 75, 5, 75],
"border": [3, 3, 117, 3, 117, 77, 3, 77],
"margin": [0, 0, 120, 0, 120, 80, 0, 80],
}
},
},
"utf16-inline-range": {
"element": [[0, 0, 200, 20]],
"all": [[0, 0, 68.859375, 20]],
"emoji": [[23.984375, 0, 20.875, 20]],
"utf16Length": 6,
"boxModels": {},
},
"nested-scroll-clip-hit-test": {
"scroller": [0, 0, 100, 80],
"wide": [-40, -30, 300, 200],
"scroll": [40, 30, 300, 200, 100, 80],
"hits": ["wide", "root"],
"boxModels": {},
},
"transform-and-paint-order-hit-test": {
"under": [20, 20, 80, 80],
"over": [30, 25, 80, 80],
"hit": "over",
"boxModels": {
"over": {
"content": [30, 25, 110, 25, 110, 105, 30, 105],
"padding": [30, 25, 110, 25, 110, 105, 30, 105],
"border": [30, 25, 110, 25, 110, 105, 30, 105],
"margin": [30, 25, 110, 25, 110, 105, 30, 105],
}
},
},
"viewport-fixed-root-scroll": {
"before": [10, 15, 40, 30],
"fixed": [10, 15, 40, 30],
"flow": [0, -50, 200, 400],
"scroll": [0, 50],
"boxModels": {},
},
}
def reserve_port() -> int:
with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as listener:
listener.bind(("127.0.0.1", 0))
return int(listener.getsockname()[1])
async def command(
client: RawCdpClient,
method: str,
params: dict[str, Any] | None = None,
*,
session_id: str | None = None,
) -> tuple[dict[str, Any], list[dict[str, Any]]]:
message_id = await client.send(method, params, session_id=session_id)
response, messages = await client.recv_until_id(message_id, timeout=10.0)
return dict(response.get("result") or {}), messages
async def wait_for_load(
client: RawCdpClient, session_id: str, messages: list[dict[str, Any]]
) -> None:
def loaded(message: dict[str, Any]) -> bool:
return (
message.get("sessionId") == session_id
and message.get("method") == "Page.loadEventFired"
)
if any(loaded(message) for message in messages):
return
deadline = asyncio.get_running_loop().time() + 10.0
while True:
remaining = deadline - asyncio.get_running_loop().time()
if remaining <= 0:
raise TimeoutError("timed out waiting for Page.loadEventFired")
message = await asyncio.wait_for(client.recv(), timeout=remaining)
if loaded(message):
return
def assert_value(label: str, actual: Any, expected: Any) -> None:
if isinstance(expected, (int, float)) and not isinstance(expected, bool):
if not isinstance(actual, (int, float)) or abs(actual - expected) > TOLERANCE:
raise AssertionError(f"{label}: expected {expected}, got {actual}")
return
if isinstance(expected, list):
if not isinstance(actual, list) or len(actual) != len(expected):
raise AssertionError(f"{label}: expected {expected}, got {actual}")
for index, (actual_item, expected_item) in enumerate(zip(actual, expected)):
assert_value(f"{label}[{index}]", actual_item, expected_item)
return
if isinstance(expected, dict):
if not isinstance(actual, dict) or actual.keys() != expected.keys():
raise AssertionError(f"{label}: expected keys {expected.keys()}, got {actual}")
for key, expected_item in expected.items():
assert_value(f"{label}.{key}", actual[key], expected_item)
return
if actual != expected:
raise AssertionError(f"{label}: expected {expected!r}, got {actual!r}")
async def cdp_box_models(
client: RawCdpClient, session_id: str, element_ids: tuple[str, ...]
) -> dict[str, Any]:
if not element_ids:
return {}
document, _ = await command(client, "DOM.getDocument", session_id=session_id)
root_id = document["root"]["nodeId"]
models: dict[str, Any] = {}
for element_id in element_ids:
node, _ = await command(
client,
"DOM.querySelector",
{"nodeId": root_id, "selector": f"#{element_id}"},
session_id=session_id,
)
result, _ = await command(
client,
"DOM.getBoxModel",
{"nodeId": node["nodeId"]},
session_id=session_id,
)
model = result["model"]
models[element_id] = {
key: model[key] for key in ("content", "padding", "border", "margin")
}
return models
async def measure_case(
client: RawCdpClient, session_id: str, case: Case, *, record: bool
) -> dict[str, Any]:
await command(
client,
"Emulation.setDeviceMetricsOverride",
{
"width": case.width,
"height": case.height,
"deviceScaleFactor": 1,
"mobile": False,
},
session_id=session_id,
)
_, messages = await command(
client,
"Page.navigate",
{"url": "data:text/html;charset=utf-8," + urllib.parse.quote(case.html)},
session_id=session_id,
)
await wait_for_load(client, session_id, messages)
result, _ = await command(
client,
"Runtime.evaluate",
{"expression": case.expression, "returnByValue": True, "awaitPromise": True},
session_id=session_id,
)
if result.get("exceptionDetails") is not None:
raise RuntimeError(f"{case.name}: Runtime.evaluate failed: {result['exceptionDetails']}")
value = dict(result["result"]["value"])
value["boxModels"] = await cdp_box_models(
client, session_id, case.box_model_ids
)
if not record:
expected = EXPECTED.get(case.name)
if expected is None:
raise AssertionError(f"{case.name}: expected geometry is not recorded")
assert_value(case.name, value, expected)
return value
async def run(binary: Path, *, record: bool) -> dict[str, Any]:
port = reserve_port()
endpoint = f"http://127.0.0.1:{port}"
with tempfile.TemporaryDirectory(
prefix="moli-layout-phase5-chromium-", ignore_cleanup_errors=True
) as profile:
process = subprocess.Popen(
[
str(binary),
"--headless=new",
"--disable-background-networking",
"--disable-default-apps",
"--disable-gpu",
"--hide-scrollbars",
"--no-first-run",
"--no-sandbox",
"--remote-debugging-address=127.0.0.1",
f"--remote-debugging-port={port}",
f"--user-data-dir={profile}",
"about:blank",
],
stdout=subprocess.DEVNULL,
stderr=subprocess.DEVNULL,
)
client: RawCdpClient | None = None
target_id: str | None = None
try:
deadline = time.monotonic() + 10.0
last_error: BaseException | None = None
while time.monotonic() < deadline:
if process.poll() is not None:
raise RuntimeError(
f"Chromium exited during startup: {process.returncode}"
)
try:
client = await connect_raw_cdp(endpoint)
break
except BaseException as error:
last_error = error
await asyncio.sleep(0.05)
if client is None:
raise TimeoutError(f"Chromium CDP startup timed out: {last_error!r}")
version, _ = await command(client, "Browser.getVersion")
target, _ = await command(client, "Target.createTarget", {"url": "about:blank"})
target_id = str(target["targetId"])
attached, _ = await command(
client,
"Target.attachToTarget",
{"targetId": target_id, "flatten": True},
)
session_id = str(attached["sessionId"])
await command(client, "Page.enable", session_id=session_id)
await command(client, "DOM.enable", session_id=session_id)
measured = {
case.name: await measure_case(client, session_id, case, record=record)
for case in fixture_cases()
}
return {
"status": "recorded" if record else "passed",
"product": version.get("product"),
"revision": version.get("revision"),
"tolerance_css_px": TOLERANCE,
"cases": measured,
}
finally:
if client is not None:
if target_id is not None:
try:
await command(client, "Target.closeTarget", {"targetId": target_id})
except BaseException:
pass
await client.websocket.close()
if process.poll() is None:
process.terminate()
try:
process.wait(timeout=3.0)
except subprocess.TimeoutExpired:
process.kill()
process.wait(timeout=3.0)
def main() -> None:
parser = argparse.ArgumentParser()
parser.add_argument("--chromium", type=Path, default=DEFAULT_CHROMIUM)
parser.add_argument("--record", action="store_true")
args = parser.parse_args()
binary = args.chromium.expanduser().resolve()
if not binary.is_file():
raise SystemExit(f"Chromium binary does not exist: {binary}")
print(json.dumps(asyncio.run(run(binary, record=args.record)), indent=2, sort_keys=True))
if __name__ == "__main__":
main()