feat(internal/librarian/java): add entries to versions.txt for new modules

internal/librarian/java/pom.go

@@ -59,13 +59,20 @@ func generatePomsIfMissing(library *config.Library, libraryDir, googleapisDir st
 	if err != nil {
 		return err
 	}
+	var newModules []string
 	for _, m := range modules {
 		if !m.isMissing {
 			continue
 		}
 		if err := writePom(filepath.Join(m.dir, "pom.xml"), m.template, m.data); err != nil {
 			return fmt.Errorf("failed to generate %s: %w", m.artifactID, err)
 		}
+		newModules = append(newModules, m.artifactID)
+	}
+	if len(newModules) > 0 {
+		if err := updateVersionsFile(libraryDir, newModules, library.Version); err != nil {
+			return fmt.Errorf("failed to update versions.txt: %w", err)
+		}
 	}
 	return nil
 }
@@ -178,3 +185,72 @@ func writePom(pomPath, templateName string, data any) (err error) {
 	}
 	return nil
 }
+
+// updateVersionsFile adds entries for new modules to versions.txt.
+// The format is: module-name:released-version:snapshot-version
+// For new modules, released-version is 0.0.0 and snapshot-version is library.Version-SNAPSHOT.
+func updateVersionsFile(libraryDir string, newModules []string, version string) error {
+	// Find the repository root (parent of library directory)
+	repoRoot := filepath.Dir(libraryDir)
+	versionsPath := filepath.Join(repoRoot, "versions.txt")
+
+	// Read existing content if file exists
+	existingContent, err := os.ReadFile(versionsPath)
+	if err != nil && !os.IsNotExist(err) {
+		return fmt.Errorf("read versions.txt: %w", err)
+	}
+
+	// Parse existing entries to avoid duplicates
+	existingModules := make(map[string]bool)
+	if len(existingContent) > 0 {
+		lines := strings.Split(string(existingContent), "\n")
+		for _, line := range lines {
+			line = strings.TrimSpace(line)
+			if line == "" || strings.HasPrefix(line, "#") {
+				continue
+			}
+			parts := strings.Split(line, ":")
+			if len(parts) >= 1 {
+				existingModules[parts[0]] = true
+			}
+		}
+	}
+
+	// Prepare new entries
+	var newEntries []string
+	snapshotVersion := version + "-SNAPSHOT"
+	for _, module := range newModules {
+		if !existingModules[module] {
+			// Format: module:released-version:snapshot-version
+			// For new modules, released version is 0.0.0
+			entry := fmt.Sprintf("%s:0.0.0:%s", module, snapshotVersion)
+			newEntries = append(newEntries, entry)
+		}
+	}
+
+	if len(newEntries) == 0 {
+		return nil // No new entries to add
+	}
+
+	// Append new entries to the file
+	f, err := os.OpenFile(versionsPath, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
+	if err != nil {
+		return fmt.Errorf("open versions.txt: %w", err)
+	}
+	defer f.Close()
+
+	// Add a newline before new entries if file doesn't end with one
+	if len(existingContent) > 0 && !strings.HasSuffix(string(existingContent), "\n") {
+		if _, err := f.WriteString("\n"); err != nil {
+			return fmt.Errorf("write newline to versions.txt: %w", err)
+		}
+	}
+
+	for _, entry := range newEntries {
+		if _, err := f.WriteString(entry + "\n"); err != nil {
+			return fmt.Errorf("write entry to versions.txt: %w", err)
+		}
+	}
+
+	return nil
+}

internal/librarian/java/pom_test.go

@@ -156,3 +156,69 @@ func TestIsPomMissing_DirMissingError(t *testing.T) {
 		t.Errorf("isPomMissing(%q) error = %v, want %v", dir, err, os.ErrNotExist)
 	}
 }
+
+func TestUpdateVersionsFile(t *testing.T) {
+	for _, test := range []struct {
+		name            string
+		existingContent string
+		newModules      []string
+		version         string
+		wantContent     string
+	}{
+		{
+			name:        "create new file with single module",
+			newModules:  []string{"proto-google-cloud-test-v1"},
+			version:     "1.2.3",
+			wantContent: "proto-google-cloud-test-v1:0.0.0:1.2.3-SNAPSHOT\n",
+		},
+		{
+			name:            "append to existing file",
+			existingContent: "proto-google-cloud-existing-v1:1.0.0:1.1.0-SNAPSHOT\n",
+			newModules:      []string{"proto-google-cloud-test-v2"},
+			version:         "1.2.3",
+			wantContent:     "proto-google-cloud-existing-v1:1.0.0:1.1.0-SNAPSHOT\nproto-google-cloud-test-v2:0.0.0:1.2.3-SNAPSHOT\n",
+		},
+		{
+			name:            "skip duplicate modules",
+			existingContent: "proto-google-cloud-test-v1:1.0.0:1.1.0-SNAPSHOT\n",
+			newModules:      []string{"proto-google-cloud-test-v1", "proto-google-cloud-test-v2"},
+			version:         "1.2.3",
+			wantContent:     "proto-google-cloud-test-v1:1.0.0:1.1.0-SNAPSHOT\nproto-google-cloud-test-v2:0.0.0:1.2.3-SNAPSHOT\n",
+		},
+		{
+			name:            "add multiple new modules",
+			existingContent: "",
+			newModules:      []string{"proto-google-cloud-test-v1", "grpc-google-cloud-test-v1"},
+			version:         "2.0.0",
+			wantContent:     "proto-google-cloud-test-v1:0.0.0:2.0.0-SNAPSHOT\ngrpc-google-cloud-test-v1:0.0.0:2.0.0-SNAPSHOT\n",
+		},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			tmpDir := t.TempDir()
+			libraryDir := filepath.Join(tmpDir, "java-test")
+			if err := os.MkdirAll(libraryDir, 0755); err != nil {
+				t.Fatal(err)
+			}
+
+			versionsPath := filepath.Join(tmpDir, "versions.txt")
+			if test.existingContent != "" {
+				if err := os.WriteFile(versionsPath, []byte(test.existingContent), 0644); err != nil {
+					t.Fatal(err)
+				}
+			}
+
+			if err := updateVersionsFile(libraryDir, test.newModules, test.version); err != nil {
+				t.Fatalf("updateVersionsFile() error = %v", err)
+			}
+
+			got, err := os.ReadFile(versionsPath)
+			if err != nil {
+				t.Fatalf("failed to read versions.txt: %v", err)
+			}
+
+			if diff := cmp.Diff(test.wantContent, string(got)); diff != "" {
+				t.Errorf("mismatch (-want +got):\n%s", diff)
+			}
+		})
+	}
+}