format options

packages/flutterfire_cli/lib/src/firebase/firebase_dart_configuration_write.dart

@@ -111,10 +111,14 @@ class FirebaseDartConfigurationWrite {
         }
 
         fileConfigurationLines.removeRange(startIndex, endIndex + 1);
+        while (startIndex < fileConfigurationLines.length &&
+            fileConfigurationLines[startIndex].trim().isEmpty) {
+          fileConfigurationLines.removeAt(startIndex);
+        }
 
         // Insert the new platform configuration
         fileConfigurationLines.insertAll(
-          startIndex - 1,
+          startIndex,
           _buildFirebaseOptions(
             options,
             platform.toLowerCase(),
@@ -177,14 +181,16 @@ class FirebaseDartConfigurationWrite {
       }
     }
 
-    return formatList(fileConfigurationLines).join('\n');
+    final result = formatList(fileConfigurationLines).join('\n');
+    return result.endsWith('\n') ? result : '$result\n';
   }
 
   String _buildConfigurationFile() {
     _stringBuffer.clear();
     _writeHeader();
     _writeClass();
-    return formatList(_stringBuffer.toString().split('\n')).join('\n');
+    final result = formatList(_stringBuffer.toString().split('\n')).join('\n');
+    return result.endsWith('\n') ? result : '$result\n';
   }
 
   // ensure only one empty line between each static property
@@ -208,7 +214,6 @@ class FirebaseDartConfigurationWrite {
           .where((entry) => entry.value != null)
           .map((entry) => "    ${entry.key}: '${entry.value}',"),
       '  );', // FirebaseOptions
-      '',
     ];
   }
 
@@ -281,14 +286,8 @@ class FirebaseDartConfigurationWrite {
   }
 
   void _writeClass() {
-    _stringBuffer.writeAll(
-      <String>[
-        'class DefaultFirebaseOptions {',
-        '  static FirebaseOptions get currentPlatform {',
-        '',
-      ],
-      '\n',
-    );
+    _stringBuffer.writeln('class DefaultFirebaseOptions {');
+    _stringBuffer.writeln('  static FirebaseOptions get currentPlatform {');
     _writeCurrentPlatformWeb();
     _stringBuffer.writeln('    switch (defaultTargetPlatform) {');
     _writeCurrentPlatformSwitchAndroid();
@@ -321,6 +320,7 @@ class FirebaseDartConfigurationWrite {
       _buildFirebaseOptions(options, platform),
       '\n',
     );
+    _stringBuffer.writeln();
   }
 
   void _writeThrowUnsupportedForPlatform(String platform, String indentation) {

packages/flutterfire_cli/test/firebase_dart_configuration_write_test.dart

@@ -7,18 +7,44 @@ import 'package:test/test.dart';
 
 void main() {
   group('FirebaseDartConfigurationWrite', () {
-    // Regression test for
-    // https://github.com/invertase/flutterfire_cli/issues/422
-    test(
-      'replaces placeholder firebase_options.dart with generated output',
-      () {
+    void testWithWriter({
+      required String testName,
+      String? initialContent,
+      FirebaseOptions? webOptions,
+      FirebaseOptions? androidOptions,
+      required void Function(String content) verify,
+    }) {
+      test(testName, () {
         final tempDir = Directory.systemTemp.createTempSync();
         addTearDown(() => tempDir.deleteSync(recursive: true));
 
         final filePath = p.join(tempDir.path, 'lib', 'firebase_options.dart');
-        File(filePath)
-          ..createSync(recursive: true)
-          ..writeAsStringSync('''
+        final file = File(filePath)..createSync(recursive: true);
+        if (initialContent != null) {
+          file.writeAsStringSync(initialContent);
+        }
+
+        final writer = FirebaseDartConfigurationWrite(
+          configurationFilePath: filePath,
+          flutterAppPath: tempDir.path,
+          firebaseProjectId: 'test-project-id',
+          webOptions: webOptions,
+          androidOptions: androidOptions,
+        );
+
+        writer.write();
+
+        final updatedContent = file.readAsStringSync();
+        verify(updatedContent);
+      });
+    }
+
+    // Regression test for
+    // https://github.com/invertase/flutterfire_cli/issues/422
+    testWithWriter(
+      testName:
+          'replaces placeholder firebase_options.dart with generated output',
+      initialContent: '''
 // File normally generated by FlutterFire CLI. This is a stand-in.
 // See README.md for details.
 import 'package:firebase_core/firebase_core.dart' show FirebaseOptions;
@@ -32,31 +58,65 @@ class DefaultFirebaseOptions {
     );
   }
 }
-''');
-
-        final writer = FirebaseDartConfigurationWrite(
-          configurationFilePath: filePath,
-          flutterAppPath: tempDir.path,
-          firebaseProjectId: 'test-project-id',
-          webOptions: const FirebaseOptions(
-            optionsSourceContent: '{}',
-            optionsSourceFileName: 'firebase-config.json',
-            apiKey: 'api-key',
-            appId: 'app-id',
-            messagingSenderId: 'sender-id',
-            projectId: 'test-project-id',
-            measurementId: 'measurement-id',
-          ),
-        );
-
-        writer.write();
-
-        final updatedContent = File(filePath).readAsStringSync();
+''',
+      webOptions: const FirebaseOptions(
+        optionsSourceContent: '{}',
+        optionsSourceFileName: 'firebase-config.json',
+        apiKey: 'api-key',
+        appId: 'app-id',
+        messagingSenderId: 'sender-id',
+        projectId: 'test-project-id',
+        measurementId: 'measurement-id',
+      ),
+      verify: (updatedContent) {
         expect(updatedContent, contains('if (kIsWeb) {'));
         expect(updatedContent, contains('return web;'));
         expect(updatedContent, contains('static const FirebaseOptions web'));
         expect(updatedContent, isNot(contains('UnimplementedError')));
       },
     );
+
+    testWithWriter(
+      testName: 'generates correct output for JUST web (golden test)',
+      webOptions: const FirebaseOptions(
+        optionsSourceContent: '{}',
+        optionsSourceFileName: 'firebase-config.json',
+        apiKey: 'api-key',
+        appId: 'app-id',
+        messagingSenderId: 'sender-id',
+        projectId: 'test-project-id',
+        measurementId: 'measurement-id',
+      ),
+      verify: (updatedContent) {
+        final goldenFile = File('test/goldens/firebase_options_just_web.dart_');
+        final expectedContent = goldenFile.readAsStringSync();
+        expect(updatedContent, equals(expectedContent));
+      },
+    );
+
+    testWithWriter(
+      testName:
+          'cleans up trailing empty lines when updating existing configuration',
+      initialContent: '''
+class DefaultFirebaseOptions {
+  static const FirebaseOptions web = FirebaseOptions(
+    apiKey: 'old-api-key',
+  );
+
+}
+''',
+      webOptions: const FirebaseOptions(
+        optionsSourceContent: '{}',
+        optionsSourceFileName: 'firebase-config.json',
+        apiKey: 'new-api-key',
+        appId: 'app-id',
+        messagingSenderId: 'sender-id',
+        projectId: 'test-project-id',
+      ),
+      verify: (updatedContent) {
+        expect(updatedContent, contains(');\n}'));
+        expect(updatedContent, isNot(contains(');\n\n}')));
+      },
+    );
   });
 }

packages/flutterfire_cli/test/goldens/firebase_options_just_web.dart_

@@ -0,0 +1,62 @@
+// File generated by FlutterFire CLI.
+// ignore_for_file: type=lint
+import 'package:firebase_core/firebase_core.dart' show FirebaseOptions;
+import 'package:flutter/foundation.dart'
+    show defaultTargetPlatform, kIsWeb, TargetPlatform;
+
+/// Default [FirebaseOptions] for use with your Firebase apps.
+///
+/// Example:
+/// ```dart
+/// import 'firebase_options.dart';
+/// // ...
+/// await Firebase.initializeApp(
+///   options: DefaultFirebaseOptions.currentPlatform,
+/// );
+/// ```
+class DefaultFirebaseOptions {
+  static FirebaseOptions get currentPlatform {
+    if (kIsWeb) {
+      return web;
+    }
+    switch (defaultTargetPlatform) {
+      case TargetPlatform.android:
+        throw UnsupportedError(
+          'DefaultFirebaseOptions have not been configured for android - '
+          'you can reconfigure this by running the FlutterFire CLI again.',
+        );
+      case TargetPlatform.iOS:
+        throw UnsupportedError(
+          'DefaultFirebaseOptions have not been configured for ios - '
+          'you can reconfigure this by running the FlutterFire CLI again.',
+        );
+      case TargetPlatform.macOS:
+        throw UnsupportedError(
+          'DefaultFirebaseOptions have not been configured for macos - '
+          'you can reconfigure this by running the FlutterFire CLI again.',
+        );
+      case TargetPlatform.windows:
+        throw UnsupportedError(
+          'DefaultFirebaseOptions have not been configured for windows - '
+          'you can reconfigure this by running the FlutterFire CLI again.',
+        );
+      case TargetPlatform.linux:
+        throw UnsupportedError(
+          'DefaultFirebaseOptions have not been configured for linux - '
+          'you can reconfigure this by running the FlutterFire CLI again.',
+        );
+      default:
+        throw UnsupportedError(
+          'DefaultFirebaseOptions are not supported for this platform.',
+        );
+    }
+  }
+
+  static const FirebaseOptions web = FirebaseOptions(
+    apiKey: 'api-key',
+    appId: 'app-id',
+    messagingSenderId: 'sender-id',
+    projectId: 'test-project-id',
+    measurementId: 'measurement-id',
+  );
+}