fix(internal/librarian): merge library dependencies, package, prefix and protos with Dart defaults (#3813)

Merge library dependencies, package, prefix and protos with Dart
defaults. If a key exists in the source, the value will NOT be
overridden.

For #3580

Author: JoeWang1127

internal/librarian/library.go

@@ -17,6 +17,7 @@ package librarian
 import (
 	"fmt"
 	"maps"
+	"strings"
 
 	"github.com/googleapis/librarian/internal/config"
 )
@@ -86,15 +87,34 @@ func fillDart(lib *config.Library, d *config.Default) *config.Library {
 	if lib.Dart.IssueTrackerURL == "" {
 		lib.Dart.IssueTrackerURL = d.Dart.IssueTrackerURL
 	}
-	if lib.Dart.Dependencies == "" {
-		lib.Dart.Dependencies = d.Dart.Dependencies
+	lib.Dart.Packages = mergeMaps(lib.Dart.Packages, d.Dart.Packages)
+	lib.Dart.Prefixes = mergeMaps(lib.Dart.Prefixes, d.Dart.Prefixes)
+	lib.Dart.Protos = mergeMaps(lib.Dart.Protos, d.Dart.Protos)
+	lib.Dart.Dependencies = mergeDartDependencies(lib.Dart.Dependencies, d.Dart.Dependencies)
+	return lib
+}
+
+// mergeDartDependencies merges library dependencies with default dependencies.
+// Duplicate dependencies in defaults will be ignored.
+func mergeDartDependencies(libDeps, defaultDeps string) string {
+	seen := make(map[string]bool)
+	var deps []string
+	for _, dep := range strings.Split(libDeps, ",") {
+		dep = strings.TrimSpace(dep)
+		if dep == "" {
+			continue
+		}
+		seen[dep] = true
+		deps = append(deps, dep)
 	}
-	if lib.Dart.Packages == nil {
-		lib.Dart.Packages = make(map[string]string)
-		maps.Copy(lib.Dart.Packages, d.Dart.Packages)
+	for _, dep := range strings.Split(defaultDeps, ",") {
+		dep = strings.TrimSpace(dep)
+		if dep == "" || seen[dep] {
+			continue
+		}
+		deps = append(deps, dep)
 	}
-
-	return lib
+	return strings.Join(deps, ",")
 }
 
 // mergePackageDependencies merges default and library package dependencies,
@@ -158,3 +178,15 @@ func applyDefaults(language string, lib *config.Library, defaults *config.Defaul
 	}
 	return fillDefaults(lib, defaults), nil
 }
+
+// mergeMaps merges key-values of src and dst maps.
+// When a key in src is already present in dst, the value in dst will NOT be overwritten
+// by the value associated with the key in src.
+func mergeMaps(dst, src map[string]string) map[string]string {
+	res := make(map[string]string)
+	maps.Copy(res, src)
+	if dst != nil {
+		maps.Copy(res, dst)
+	}
+	return res
+}

internal/librarian/library_test.go

@@ -84,6 +84,13 @@ func TestFillDefaults(t *testing.T) {
 						"package:one": "^1.2.3",
 						"package:two": "^2.0.0",
 					},
+					Prefixes: map[string]string{
+						"prefix:google.logging.type": "logging_type",
+					},
+					Protos: map[string]string{
+						"proto:google.api":          "package:google_cloud_api/api.dart",
+						"proto:google.cloud.common": "package:google_cloud_common/common.dart",
+					},
 					Version: "0.4.0",
 				},
 			},
@@ -96,6 +103,13 @@ func TestFillDefaults(t *testing.T) {
 					Dependencies:                "dep-1,dep-2",
 					IssueTrackerURL:             "https://issue-tracker-example/dart",
 					Packages:                    map[string]string{"package:one": "^1.2.3", "package:two": "^2.0.0"},
+					Prefixes: map[string]string{
+						"prefix:google.logging.type": "logging_type",
+					},
+					Protos: map[string]string{
+						"proto:google.api":          "package:google_cloud_api/api.dart",
+						"proto:google.cloud.common": "package:google_cloud_common/common.dart",
+					},
 				},
 			},
 		},
@@ -110,6 +124,13 @@ func TestFillDefaults(t *testing.T) {
 						"package:one": "^1.2.3",
 						"package:two": "^2.0.0",
 					},
+					Prefixes: map[string]string{
+						"prefix:google.logging.type": "logging_type",
+					},
+					Protos: map[string]string{
+						"proto:google.api":          "package:google_cloud_api/api.dart",
+						"proto:google.cloud.common": "package:google_cloud_common/common.dart",
+					},
 					Version: "0.4.0",
 				},
 			},
@@ -118,23 +139,39 @@ func TestFillDefaults(t *testing.T) {
 				Version: "0.5.0",
 				Dart: &config.DartPackage{
 					APIKeysEnvironmentVariables: "apiKey-3,apiKey-4",
-					Dependencies:                "dep-3,dep-4",
+					Dependencies:                "dep-1,dep-3,dep-4",
 					IssueTrackerURL:             "https://another-issue-tracker-example/dart",
 					Packages: map[string]string{
 						"package:three": "^1.0.0",
 					},
+					Prefixes: map[string]string{
+						"prefix:google.logging.type": "logging_type_v2",
+					},
+					Protos: map[string]string{
+						"proto:google.cloud.location": "package:google_cloud_location/location.dart",
+					},
 				},
 			},
 			want: &config.Library{
 				Output:  "foo/",
 				Version: "0.5.0",
 				Dart: &config.DartPackage{
 					APIKeysEnvironmentVariables: "apiKey-3,apiKey-4",
-					Dependencies:                "dep-3,dep-4",
+					Dependencies:                "dep-1,dep-3,dep-4,dep-2",
 					IssueTrackerURL:             "https://another-issue-tracker-example/dart",
 					Packages: map[string]string{
+						"package:one":   "^1.2.3",
+						"package:two":   "^2.0.0",
 						"package:three": "^1.0.0",
 					},
+					Prefixes: map[string]string{
+						"prefix:google.logging.type": "logging_type_v2",
+					},
+					Protos: map[string]string{
+						"proto:google.cloud.location": "package:google_cloud_location/location.dart",
+						"proto:google.api":            "package:google_cloud_api/api.dart",
+						"proto:google.cloud.common":   "package:google_cloud_common/common.dart",
+					},
 				},
 			},
 		},