tests(e2e): Allow tests to run only on file changes

- supports glob patterns in testfiles
- only runs tests on changes
- always runs tests without specified patterns

tests(e2e): refactor global watch patterns

tests(e2e): add watch patterns to test files

tests/e2e/changes.go

@@ -0,0 +1,114 @@
+// Copyright 2024 The Forgejo Authors. All rights reserved.
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+package e2e
+
+import (
+	"bufio"
+	"os"
+	"strings"
+
+	"code.gitea.io/gitea/modules/log"
+
+	"github.com/gobwas/glob"
+)
+
+var (
+	changesetFiles     []string
+	changesetAvailable bool
+	globalFullRun      bool
+)
+
+func initChangedFiles() {
+	var changes string
+	changes, changesetAvailable = os.LookupEnv("CHANGED_FILES")
+	// the output of the Action seems to actually contain \n and not a newline literal
+	changesetFiles = strings.Split(changes, `\n`)
+	log.Info("Only running tests covered by a subset of test files. Received the following list of CHANGED_FILES: %q", changesetFiles)
+
+	globalPatterns := []string{
+		// meta and config
+		"Makefile",
+		"playwright.config.js",
+		".forgejo/workflows/testing.yml",
+		"tests/e2e/*.go",
+		"tests/e2e/shared/*",
+		// frontend files
+		"frontend/*.js",
+		"frontend/{base,index}.css",
+		// templates
+		"templates/base/**",
+	}
+	fullRunPatterns := []glob.Glob{}
+	for _, expr := range globalPatterns {
+		fullRunPatterns = append(fullRunPatterns, glob.MustCompile(expr, '.', '/'))
+	}
+	globalFullRun = false
+	for _, changedFile := range changesetFiles {
+		for _, pattern := range fullRunPatterns {
+			if pattern.Match(changedFile) {
+				globalFullRun = true
+				log.Info("Changed files match global test pattern, running all tests")
+				return
+			}
+		}
+	}
+}
+
+func canSkipTest(testFile string) bool {
+	// run all tests when environment variable is not set or changes match global pattern
+	if !changesetAvailable || globalFullRun {
+		return false
+	}
+
+	for _, changedFile := range changesetFiles {
+		if strings.HasSuffix(testFile, changedFile) {
+			return false
+		}
+		for _, pattern := range getWatchPatterns(testFile) {
+			if pattern.Match(changedFile) {
+				return false
+			}
+		}
+	}
+	return true
+}
+
+func getWatchPatterns(filename string) []glob.Glob {
+	file, err := os.Open(filename)
+	if err != nil {
+		log.Fatal(err.Error())
+	}
+	defer file.Close()
+	scanner := bufio.NewScanner(file)
+
+	watchSection := false
+	patterns := []glob.Glob{}
+	for scanner.Scan() {
+		line := scanner.Text()
+		// check for watch block
+		if strings.HasPrefix(line, "// @watch") {
+			if watchSection {
+				break
+			}
+			watchSection = true
+		}
+		if !watchSection {
+			continue
+		}
+
+		line = strings.TrimPrefix(line, "// ")
+		if line != "" {
+			globPattern, err := glob.Compile(line, '.', '/')
+			if err != nil {
+				log.Fatal("Invalid glob pattern '%s' (skipped): %v", line, err)
+			}
+			patterns = append(patterns, globPattern)
+		}
+	}
+	// if no watch block in file
+	if !watchSection {
+		patterns = append(patterns, glob.MustCompile("*"))
+	}
+	return patterns
+}