test_runner: add test_crafted_wal_end.py

For some reason both non-`simple` tests spend about 10 seconds
in the post-restart `INSERT INTO` query on my machine, see #2023

test_runner/batch_others/test_crafted_wal_end.py

@@ -0,0 +1,61 @@
+from fixtures.neon_fixtures import NeonEnvBuilder, WalGenerate
+from fixtures.log_helper import log
+import pytest
+
+# Restart nodes with WAL end having specially crafted shape, like last record
+# crossing segment boundary, to test decoding issues.
+
+
+@pytest.mark.parametrize('wal_type',
+                         [
+                             'simple',
+                             'last_wal_record_crossing_segment',
+                             'wal_record_crossing_segment_followed_by_small_one',
+                         ])
+def test_crafted_wal_end(neon_env_builder: NeonEnvBuilder, wal_type: str):
+    neon_env_builder.num_safekeepers = 1
+    env = neon_env_builder.init_start()
+    env.neon_cli.create_branch('test_crafted_wal_end')
+
+    pg = env.postgres.create('test_crafted_wal_end')
+    gen = WalGenerate(env)
+    pg.config(gen.postgres_config())
+    pg.start()
+    res = pg.safe_psql_many(queries=[
+        'CREATE TABLE keys(key int primary key)',
+        'INSERT INTO keys SELECT generate_series(1, 100)',
+        'SELECT SUM(key) FROM keys'
+    ])
+    assert res[-1][0] == (5050, )
+
+    gen.in_existing(wal_type, pg.connstr())
+
+    log.info("Restarting all safekeepers and pageservers")
+    env.pageserver.stop()
+    env.safekeepers[0].stop()
+    env.safekeepers[0].start()
+    env.pageserver.start()
+
+    log.info("Trying more queries")
+    res = pg.safe_psql_many(queries=[
+        'SELECT SUM(key) FROM keys',
+        'INSERT INTO keys SELECT generate_series(101, 200)',
+        'SELECT SUM(key) FROM keys',
+    ])
+    assert res[0][0] == (5050, )
+    assert res[-1][0] == (20100, )
+
+    log.info("Restarting all safekeepers and pageservers (again)")
+    env.pageserver.stop()
+    env.safekeepers[0].stop()
+    env.safekeepers[0].start()
+    env.pageserver.start()
+
+    log.info("Trying more queries (again)")
+    res = pg.safe_psql_many(queries=[
+        'SELECT SUM(key) FROM keys',
+        'INSERT INTO keys SELECT generate_series(201, 300)',
+        'SELECT SUM(key) FROM keys',
+    ])
+    assert res[0][0] == (20100, )
+    assert res[-1][0] == (45150, )