fix(internal/gapicgen): properly update modules that have no gapic changes

internal/gapicgen/generator/gapics.go

@@ -29,7 +29,6 @@ import (
 	"cloud.google.com/go/internal/gapicgen/execv"
 	"cloud.google.com/go/internal/gapicgen/execv/gocmd"
 	"cloud.google.com/go/internal/gapicgen/gensnippets"
-	"cloud.google.com/go/internal/gapicgen/git"
 	"gopkg.in/yaml.v2"
 )
 
@@ -617,33 +616,6 @@ func ParseAPIShortnames(googleapisDir string, confs []*MicrogenConfig, manualEnt
 	return shortnames, nil
 }
 
-func (g *GapicGenerator) findModifiedDirs() ([]string, error) {
-	log.Println("finding modifiled directories")
-	files, err := git.FindModifiedAndUntrackedFiles(g.googleCloudDir)
-	if err != nil {
-		return nil, err
-	}
-	dirs := map[string]bool{}
-	for _, file := range files {
-		dir := filepath.Dir(filepath.Join(g.googleCloudDir, file))
-		dirs[dir] = true
-	}
-
-	// Add modified dirs from genproto. Sometimes only a request struct will be
-	// updated, in these cases we should still make modifications the
-	// corresponding gapic directories.
-	for _, pkg := range g.modifiedPkgs {
-		dir := filepath.Join(g.googleCloudDir, pkg)
-		dirs[dir] = true
-	}
-
-	var dirList []string
-	for dir := range dirs {
-		dirList = append(dirList, dir)
-	}
-	return dirList, nil
-}
-
 func docURL(cloudDir, importPath string) (string, error) {
 	suffix := strings.TrimPrefix(importPath, "cloud.google.com/go/")
 	mod, err := gocmd.CurrentMod(filepath.Join(cloudDir, suffix))

internal/gapicgen/git/github.go

@@ -24,6 +24,7 @@ import (
 	"os/user"
 	"path"
 	"path/filepath"
+	"regexp"
 	"strings"
 	"time"
 
@@ -68,6 +69,8 @@ genbot to assign reviewers to the google-cloud-go PR.
 `
 )
 
+var conventionalCommitScopeRe = regexp.MustCompile(`.*\((.*)\): .*`)
+
 // PullRequest represents a GitHub pull request.
 type PullRequest struct {
 	Author  string
@@ -402,6 +405,15 @@ func updateDeps(tmpDir string) error {
 		updatedModDirs[modDir] = true
 	}
 
+	// Find modules based on conventional commit messages.
+	commitModDirs, err := processCommitMessage(tmpDir)
+	if err != nil {
+		return err
+	}
+	for _, v := range commitModDirs {
+		updatedModDirs[v] = true
+	}
+
 	// Update required modules.
 	for modDir := range updatedModDirs {
 		log.Printf("Updating module dir %q", modDir)
@@ -442,3 +454,40 @@ fi
 	c.Dir = tmpDir
 	return c.Run()
 }
+
+// processCommitMessage process the context aware commits mentioned in the PR
+// body to determine what modules need to have dependency bumps.
+func processCommitMessage(dir string) ([]string, error) {
+	c := execv.Command("git", "log", "-1", "--pretty=%B")
+	c.Dir = dir
+	out, err := c.Output()
+	if err != nil {
+		return nil, err
+	}
+	outStr := string(out)
+	ss := strings.Split(outStr, "Changes:\n\n")
+	if len(ss) != 2 {
+		return nil, fmt.Errorf("unable to process commit msg")
+	}
+	commits := strings.Split(ss[1], "\n\n")
+	var modDirs []string
+	for _, v := range commits {
+		pkg := parsePackage(v)
+		if pkg == "" {
+			continue
+		}
+		modDirs = append(modDirs, filepath.Join(dir, pkg))
+	}
+	return modDirs, nil
+}
+
+// parsePackage parses a package name from the conventional commit scope of a
+// commit message.
+func parsePackage(msg string) string {
+	matches := conventionalCommitScopeRe.FindStringSubmatch(msg)
+	if len(matches) < 2 {
+		return ""
+	}
+	return matches[1]
+
+}

internal/gapicgen/git/github_test.go

@@ -0,0 +1,39 @@
+// Copyright 2022 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package git
+
+import "testing"
+
+func TestParsePackage(t *testing.T) {
+	tests := []struct {
+		name  string
+		input string
+		want  string
+	}{
+		{"found basic package", "feat(foo): something", "foo"},
+		{"found nested package", "fix(foo/bar): something", "foo/bar"},
+		{"no scope", "chore: something", ""},
+		{"bad commit msg", "something happend", ""},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			got := parsePackage(tc.input)
+			if got != tc.want {
+				t.Errorf("got %q, want %q", got, tc.want)
+			}
+		})
+	}
+}