mirror of
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J. Nick Koston
9ed16b63a3
Persist the result of pytest --collect-only between CI runs as a JSON file keyed by content hash, so unchanged test files are served from cache and only edited or new files are re-collected. The cache is self-healing: * Missing, corrupt, or wrong-version files fall back to a full collect. * Any conftest.py change anywhere under the test root invalidates the whole cache, so fixture parametrization shifts cannot silently skew counts. * Files pytest returns nothing for (helper modules named test_*.py with no test functions) are cached as zero so they don't get re-collected forever. Walking is done once with os.walk (~2x faster than Path.rglob) and collects test files plus conftests in a single pass. When the cache is fully cold we feed pytest top-level directories rather than thousands of file paths so cold runs stay as fast as before the cache landed. Wire the new --cache flag through the prepare-pytest-full job and back the cache file with actions/cache so PRs can pick up the latest dev snapshot via restore-keys. Local timings: cold 11s, warm with no diff 0.4s, warm with one file edited 2.3s.
513 lines
18 KiB
Python
Executable File
513 lines
18 KiB
Python
Executable File
#!/usr/bin/env python3
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"""Helper script to split test into n buckets."""
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import argparse
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from concurrent.futures import ProcessPoolExecutor
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from dataclasses import dataclass, field
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import hashlib
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import json
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from math import ceil
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import os
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from pathlib import Path
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import subprocess
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import sys
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from typing import Final
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# tests/components has ~1000 sub-directories, which makes it the natural
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# place to subdivide to keep each pytest invocation roughly equal in size.
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_FAN_OUT_DIRS: Final = frozenset({"components"})
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# Cache file format version; bump on any incompatible schema change so old
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# caches are ignored rather than misread.
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_CACHE_VERSION: Final = 1
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class Bucket:
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"""Class to hold bucket."""
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def __init__(self) -> None:
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"""Initialize bucket."""
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self.total_tests = 0
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self._paths: list[str] = []
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def add(self, part: TestFolder | TestFile) -> None:
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"""Add tests to bucket."""
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part.add_to_bucket()
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self.total_tests += part.total_tests
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self._paths.append(str(part.path))
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def get_paths_line(self) -> str:
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"""Return paths."""
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return " ".join(self._paths) + "\n"
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class BucketHolder:
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"""Class to hold buckets."""
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def __init__(self, tests_per_bucket: int, bucket_count: int) -> None:
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"""Initialize bucket holder."""
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self._tests_per_bucket = tests_per_bucket
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self._bucket_count = bucket_count
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self._buckets: list[Bucket] = [Bucket() for _ in range(bucket_count)]
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def split_tests(self, test_folder: TestFolder) -> None:
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"""Split tests into buckets."""
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digits = len(str(test_folder.total_tests))
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sorted_tests = sorted(
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test_folder.get_all_flatten(), reverse=True, key=lambda x: x.total_tests
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)
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for tests in sorted_tests:
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if tests.added_to_bucket:
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# Already added to bucket
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continue
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print(f"{tests.total_tests:>{digits}} tests in {tests.path}")
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smallest_bucket = min(self._buckets, key=lambda x: x.total_tests)
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is_file = isinstance(tests, TestFile)
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if (
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smallest_bucket.total_tests + tests.total_tests < self._tests_per_bucket
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) or is_file:
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smallest_bucket.add(tests)
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# Ensure all files from the same folder are in the same bucket
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# to ensure that syrupy correctly identifies unused snapshots
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if is_file:
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for other_test in tests.parent.children.values():
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if other_test is tests or isinstance(other_test, TestFolder):
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continue
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print(
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f"{other_test.total_tests:>{digits}}"
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f" tests in {other_test.path}"
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" (same bucket)"
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)
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smallest_bucket.add(other_test)
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# verify that all tests are added to a bucket
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if not test_folder.added_to_bucket:
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raise ValueError("Not all tests are added to a bucket")
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def create_ouput_file(self) -> None:
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"""Create output file."""
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with Path("pytest_buckets.txt").open("w", encoding="utf-8") as file:
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for idx, bucket in enumerate(self._buckets):
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print(f"Bucket {idx + 1} has {bucket.total_tests} tests")
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file.write(bucket.get_paths_line())
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@dataclass
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class TestFile:
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"""Class represents a single test file and the number of tests it has."""
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total_tests: int
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path: Path
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added_to_bucket: bool = field(default=False, init=False)
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parent: TestFolder | None = field(default=None, init=False)
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def add_to_bucket(self) -> None:
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"""Add test file to bucket."""
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if self.added_to_bucket:
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raise ValueError("Already added to bucket")
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self.added_to_bucket = True
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def __gt__(self, other: TestFile) -> bool:
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"""Return if greater than."""
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return self.total_tests > other.total_tests
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class TestFolder:
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"""Class to hold a folder with test files and folders."""
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def __init__(self, path: Path) -> None:
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"""Initialize test folder."""
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self.path: Final = path
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self.children: dict[Path, TestFolder | TestFile] = {}
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@property
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def total_tests(self) -> int:
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"""Return total tests."""
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return sum([test.total_tests for test in self.children.values()])
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@property
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def added_to_bucket(self) -> bool:
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"""Return if added to bucket."""
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return all(test.added_to_bucket for test in self.children.values())
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def add_to_bucket(self) -> None:
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"""Add test file to bucket."""
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if self.added_to_bucket:
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raise ValueError("Already added to bucket")
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for child in self.children.values():
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child.add_to_bucket()
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def __repr__(self) -> str:
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"""Return representation."""
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return (
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f"TestFolder(total_tests={self.total_tests}, children={len(self.children)})"
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)
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def add_test_file(self, file: TestFile) -> None:
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"""Add test file to folder."""
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path = file.path
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file.parent = self
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relative_path = path.relative_to(self.path)
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if not relative_path.parts:
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raise ValueError("Path is not a child of this folder")
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if len(relative_path.parts) == 1:
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self.children[path] = file
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return
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child_path = self.path / relative_path.parts[0]
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if (child := self.children.get(child_path)) is None:
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self.children[child_path] = child = TestFolder(child_path)
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elif not isinstance(child, TestFolder):
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raise ValueError("Child is not a folder")
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child.add_test_file(file)
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def get_all_flatten(self) -> list[TestFolder | TestFile]:
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"""Return self and all children as flatten list."""
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result: list[TestFolder | TestFile] = [self]
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for child in self.children.values():
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if isinstance(child, TestFolder):
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result.extend(child.get_all_flatten())
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else:
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result.append(child)
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return result
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def _collect_batch(paths: list[Path]) -> tuple[str, str, int]:
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"""Run pytest --collect-only on a batch of paths."""
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result = subprocess.run(
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["pytest", "--collect-only", "-qq", "-p", "no:warnings", *map(str, paths)],
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check=False,
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capture_output=True,
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text=True,
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)
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return result.stdout, result.stderr, result.returncode
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def _iter_eligible_children(path: Path) -> list[Path]:
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"""Return immediate children of ``path`` that pytest should collect.
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Filters out hidden/dunder entries, non-``test_*.py`` files (so helper
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modules like ``conftest.py`` and ``common.py`` are not passed as
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explicit collection targets), and pycache-style directories.
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"""
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children: list[Path] = []
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for entry in sorted(path.iterdir()):
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if entry.name.startswith((".", "_")):
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continue
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if entry.is_dir() or (entry.suffix == ".py" and entry.name.startswith("test_")):
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children.append(entry)
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return children
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def _enumerate_batch_paths(path: Path) -> list[Path]:
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"""Return the child paths to run pytest --collect-only over.
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Files are returned as-is. Directories are expanded one level deep, with
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a second level of expansion for entries named in ``_FAN_OUT_DIRS`` so the
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enormous ``tests/components`` tree fans out into per-integration paths.
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"""
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if path.is_file():
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return [path]
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paths: list[Path] = []
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for entry in _iter_eligible_children(path):
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if entry.is_dir() and entry.name in _FAN_OUT_DIRS:
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paths.extend(_iter_eligible_children(entry))
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else:
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paths.append(entry)
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return paths
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def _hash_file(path: Path) -> str:
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"""Return a short content hash for ``path``."""
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return hashlib.sha256(path.read_bytes()).hexdigest()[:16]
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def _walk_test_tree(root: Path) -> tuple[list[Path], list[Path]]:
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"""Walk ``root`` once and return (test files, conftest files).
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Uses ``os.walk`` rather than ``Path.rglob`` because it's ~2x faster on
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a 5000-file tree, and we prune hidden/dunder subdirectories instead of
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visiting them. Doing both walks in one pass keeps total tree I/O down.
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"""
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if root.is_file():
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if root.name.startswith("test_") and root.suffix == ".py":
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return [root], []
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return [], []
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test_files: list[Path] = []
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conftests: list[Path] = []
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for dirpath, dirnames, filenames in os.walk(root):
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dirnames[:] = [d for d in dirnames if not d.startswith((".", "_"))]
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base = Path(dirpath)
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for name in filenames:
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if name == "conftest.py":
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conftests.append(base / name)
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elif name.startswith("test_") and name.endswith(".py"):
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test_files.append(base / name)
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test_files.sort()
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conftests.sort()
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return test_files, conftests
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def _compute_conftest_hash(root: Path, conftests: list[Path]) -> str:
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"""Return a hash that changes whenever any conftest.py under ``root`` changes.
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Any change to a conftest invalidates the entire test-count cache. This is
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coarse but safe: conftests can change fixture parametrization in ways the
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cache cannot otherwise detect, so we just re-collect everything.
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"""
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digest = hashlib.sha256()
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for conftest in conftests:
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digest.update(str(conftest.relative_to(root)).encode())
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digest.update(b"\0")
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digest.update(conftest.read_bytes())
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digest.update(b"\0")
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return digest.hexdigest()
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@dataclass
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class _CacheEntry:
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"""Cached test count for a single file."""
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hash: str
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count: int
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@dataclass
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class _Cache:
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"""Mapping of test file path → cached entry, plus invalidation key."""
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conftest_hash: str
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entries: dict[str, _CacheEntry]
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@classmethod
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def empty(cls, conftest_hash: str = "") -> _Cache:
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"""Return a new empty cache."""
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return cls(conftest_hash=conftest_hash, entries={})
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@classmethod
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def load(cls, path: Path, current_conftest_hash: str) -> _Cache:
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"""Load cache from ``path`` and invalidate it on schema/conftest drift.
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Any failure (missing file, bad JSON, version drift, conftest drift)
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returns an empty cache so the script just falls back to a full
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collection. This is the self-healing path.
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"""
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try:
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raw = json.loads(path.read_bytes())
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except OSError, ValueError:
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return cls.empty(current_conftest_hash)
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if not isinstance(raw, dict) or raw.get("version") != _CACHE_VERSION:
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return cls.empty(current_conftest_hash)
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if raw.get("conftest_hash") != current_conftest_hash:
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return cls.empty(current_conftest_hash)
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files = raw.get("files")
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if not isinstance(files, dict):
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return cls.empty(current_conftest_hash)
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entries: dict[str, _CacheEntry] = {}
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for key, value in files.items():
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if (
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not isinstance(value, dict)
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or not isinstance(value.get("hash"), str)
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or not isinstance(value.get("count"), int)
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):
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# Skip malformed entries instead of discarding the whole cache.
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continue
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entries[key] = _CacheEntry(hash=value["hash"], count=value["count"])
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return cls(conftest_hash=current_conftest_hash, entries=entries)
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def save(self, path: Path) -> None:
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"""Write the cache to ``path``."""
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path.write_text(
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json.dumps(
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{
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"version": _CACHE_VERSION,
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"conftest_hash": self.conftest_hash,
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"files": {
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key: {"hash": entry.hash, "count": entry.count}
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for key, entry in sorted(self.entries.items())
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},
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},
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indent=2,
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)
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+ "\n"
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)
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def _resolve_from_cache(
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test_files: list[Path],
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cache: _Cache,
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root: Path,
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) -> tuple[dict[Path, int], list[Path]]:
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"""Split ``test_files`` into ``(cached_counts, needs_collection)``.
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A file is served from cache when its content hash matches what we
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previously stored; otherwise it is queued for re-collection.
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"""
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cached: dict[Path, int] = {}
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misses: list[Path] = []
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for file in test_files:
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key = str(file.relative_to(root))
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entry = cache.entries.get(key)
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if entry is None:
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misses.append(file)
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continue
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if entry.hash != _hash_file(file):
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misses.append(file)
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continue
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cached[file] = entry.count
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return cached, misses
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def _run_collect_batches(paths: list[Path]) -> list[tuple[str, str, int]]:
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"""Run pytest --collect-only across ``paths`` using a process pool."""
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workers = min(len(paths), os.cpu_count() or 1) or 1
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batches = [paths[i::workers] for i in range(workers)]
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if workers == 1:
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return [_collect_batch(batches[0])]
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with ProcessPoolExecutor(max_workers=workers) as executor:
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return list(executor.map(_collect_batch, batches))
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def _parse_collect_output(stdout: str) -> dict[Path, int]:
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"""Parse ``pytest --collect-only -qq`` output into ``{path: count}``."""
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counts: dict[Path, int] = {}
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for line in stdout.splitlines():
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if not line.strip():
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continue
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file_path, _, total_tests = line.partition(": ")
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if not file_path or not total_tests:
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raise ValueError(f"Unexpected line: {line}")
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counts[Path(file_path)] = int(total_tests)
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return counts
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def collect_tests(path: Path, cache_path: Path | None = None) -> TestFolder:
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"""Collect all tests, using an on-disk cache when available."""
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all_test_files, conftests = _walk_test_tree(path)
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conftest_hash = _compute_conftest_hash(path, conftests)
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cache = (
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_Cache.load(cache_path, conftest_hash)
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if cache_path is not None
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else _Cache.empty(conftest_hash)
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)
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if not all_test_files:
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print(f"No eligible test paths found under {path}")
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sys.exit(1)
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cached_counts, missing = _resolve_from_cache(all_test_files, cache, path)
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print(
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f"Cache: {len(cached_counts)} hits / {len(missing)} misses"
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f" / {len(all_test_files)} total"
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)
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new_counts: dict[Path, int] = {}
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if missing:
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# On a full cold-cache run, hand pytest the top-level directories
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# instead of 5000+ individual file paths: pytest walks dirs much
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# faster than it resolves each file argument. Once any cache hits
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# exist, use file-level collection so we only re-collect the diff.
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if not cached_counts:
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collect_paths = _enumerate_batch_paths(path)
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else:
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collect_paths = missing
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results = _run_collect_batches(collect_paths)
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for stdout, stderr, returncode in results:
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if returncode != 0:
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print("Failed to collect tests:")
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print(stderr)
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print(stdout)
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sys.exit(1)
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try:
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new_counts.update(_parse_collect_output(stdout))
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except ValueError as err:
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print(err)
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sys.exit(1)
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counts: dict[Path, int] = {**cached_counts, **new_counts}
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folder = TestFolder(path)
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for file_path, total_tests in counts.items():
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if total_tests == 0:
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# Files with no collected tests (eg helper modules named
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# test_init.py with no test functions) shouldn't enter
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# bucketing, but we still cache them below as count=0 so
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# they don't get re-collected next run.
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continue
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folder.add_test_file(TestFile(total_tests, file_path))
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if cache_path is not None:
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# Rebuild the cache from scratch on every run so deleted files are
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# dropped and re-collected files get a refreshed hash.
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missing_set = set(missing)
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updated_entries: dict[str, _CacheEntry] = {}
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for file in all_test_files:
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if file in counts:
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count = counts[file]
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elif file in missing_set:
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# We asked pytest about this file and got no count back,
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# so it has no collectible tests; cache it as 0 to avoid
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# repeating the work next run.
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count = 0
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else:
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continue
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updated_entries[str(file.relative_to(path))] = _CacheEntry(
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hash=_hash_file(file), count=count
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)
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_Cache(conftest_hash=conftest_hash, entries=updated_entries).save(cache_path)
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return folder
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def main() -> None:
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"""Execute script."""
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parser = argparse.ArgumentParser(description="Split tests into n buckets.")
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def check_greater_0(value: str) -> int:
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ivalue = int(value)
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if ivalue <= 0:
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raise argparse.ArgumentTypeError(
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f"{value} is an invalid. Must be greater than 0"
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)
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return ivalue
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parser.add_argument(
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"bucket_count",
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help="Number of buckets to split tests into",
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type=check_greater_0,
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)
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parser.add_argument(
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"path",
|
|
help="Path to the test files to split into buckets",
|
|
type=Path,
|
|
)
|
|
parser.add_argument(
|
|
"--cache",
|
|
help="Path to a JSON file used to cache per-file test counts",
|
|
type=Path,
|
|
default=None,
|
|
)
|
|
|
|
arguments = parser.parse_args()
|
|
|
|
print("Collecting tests...")
|
|
tests = collect_tests(arguments.path, arguments.cache)
|
|
tests_per_bucket = ceil(tests.total_tests / arguments.bucket_count)
|
|
|
|
bucket_holder = BucketHolder(tests_per_bucket, arguments.bucket_count)
|
|
print("Splitting tests...")
|
|
bucket_holder.split_tests(tests)
|
|
|
|
print(f"Total tests: {tests.total_tests}")
|
|
print(f"Estimated tests per bucket: {tests_per_bucket}")
|
|
|
|
bucket_holder.create_ouput_file()
|
|
|
|
|
|
if __name__ == "__main__":
|
|
main()
|