go/src/infra/rts/cmd/rts-chromium/strategy.go

// Copyright 2020 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

package main

import (
	"context"
	"fmt"
	"path"
	"regexp"
	"strings"

	"go.chromium.org/luci/common/errors"
	"go.chromium.org/luci/common/logging"

	"infra/rts"
	"infra/rts/filegraph/git"
	"infra/rts/presubmit/eval"
	evalpb "infra/rts/presubmit/eval/proto"
)

// The range of the number of changed files to enable RTS.
// If the number of changed files is not in this range, then RTS is disabled.
// Note that 99.3% of developer-authored git commits change <= 100 files, see bit.ly/chromium-rts
const (
	minChangedFiles = 1
	maxChangedFiles = 100
)

// mustAlwaysRunTest returns true if the test file must never be skipped.
func mustAlwaysRunTest(testFile string) bool {
	switch {
	// Always run all third-party tests (never skip them),
	// except //third_party/blink which is actually first party.
	case strings.Contains(testFile, "/third_party/") && !strings.HasPrefix(testFile, "//third_party/blink/"):
		return true

	case testFile == "//third_party/blink/web_tests/wpt_internal/webgpu/cts.html":
		// Most of cts.html commits are auto-generated.
		// https://source.chromium.org/chromium/chromium/src/+/HEAD:third_party/blink/web_tests/wpt_internal/webgpu/cts.html;l=5;bpv=1;bpt=0
		// cts.html does not have meaningful edges in the file graph.
		return true

	default:
		return false
	}
}

var (
	// requireAllTests is a list of patterns of files that require running all
	// tests.
	requireAllTests = []string{
		// A CL changes the way tests run or their configurations.
		"//testing/.+",

		// The full list of modified files is not available, and the
		// graph does not include DEPSed file changes anyway.
		"//DEPS",

		// MB CLs change the way tests run or their configurations.
		"//tools/mb/.+",
	}
	requireAllTestsRegexp = regexp.MustCompile(fmt.Sprintf("^(%s)$", strings.Join(requireAllTests, "|")))

	disableRTS = errors.BoolTag{Key: errors.NewTagKey("skip RTS")}
)

// selectTests calls skipFile for test files that should be skipped.
// May return an error annotated with disableRTS tag and the message explaining
// why RTS was disabled.
func (r *selectRun) selectTests(skipFile func(*TestFile) error) (err error) {
	// Disable RTS if the number of files is unusual.
	if len(r.changedFiles) < minChangedFiles || len(r.changedFiles) > maxChangedFiles {
		return errors.Reason(
			"%d files were changed, which is outside of [%d, %d] range",
			len(r.changedFiles),
			minChangedFiles,
			maxChangedFiles,
		).Tag(disableRTS).Err()
	}

	// Check if any of the changed files requires all tests.
	for f := range r.changedFiles {
		if requireAllTestsRegexp.MatchString(f) {
			return errors.Reason(
				"%q was changed, which matches regexp %s",
				f,
				requireAllTests,
			).Tag(disableRTS).Err()
		}
	}
	r.strategy.Select(r.changedFiles.ToSlice(), func(fileName string) (keepGoing bool) {
		file, ok := r.testFiles[fileName]
		if !ok {
			return true
		}
		err = skipFile(file)
		return err == nil
	})
	return
}

func (r *createModelRun) evalStrategy(er *git.EdgeReader) eval.Strategy {
	s := &git.SelectionStrategy{
		Graph:      r.fg,
		EdgeReader: er,
		OnTestNotFound: func(ctx context.Context, tv *evalpb.TestVariant) {
			if strings.Contains(path.Base(tv.FileName), "autogen") {
				// This file is autogenerated.
				return
			}
			logging.Warningf(ctx, "test file not found: %s", tv.FileName)
		},
	}

	return func(ctx context.Context, in eval.Input, out *eval.Output) error {
		for _, f := range in.ChangedFiles {
			switch {
			case f.Repo != "https://chromium.googlesource.com/chromium/src":
				return errors.Reason("unexpected repo %q", f.Repo).Err()
			case requireAllTestsRegexp.MatchString(f.Path):
				return nil
			}
		}

		if err := s.SelectEval(ctx, in, out); err != nil {
			return err
		}

		// No matter what filegraph said, never skip certain tests.
		for i, tv := range in.TestVariants {
			if mustAlwaysRunTest(tv.FileName) {
				out.TestVariantAffectedness[i] = rts.Affectedness{Distance: 0}
			}
		}
		return nil
	}
}