feat(test): add --update-goldens (#341)

Author: felangel

README.md

@@ -170,6 +170,7 @@ Usage: very_good test [arguments]
 -x, --exclude-tags                    Run only tests that do not have the specified tags.
     --min-coverage                    Whether to enforce a minimum coverage percentage.
     --test-randomize-ordering-seed    The seed to randomize the execution order of test cases within test files.
+    --update-goldens                  Whether "matchesGoldenFile()" calls within your test methods should update the golden files.
 
 Run "very_good help" to see global options.
 ```

lib/src/commands/test/test.dart

@@ -73,6 +73,12 @@ class TestCommand extends Command<int> {
         'test-randomize-ordering-seed',
         help: 'The seed to randomize the execution order of test cases '
             'within test files.',
+      )
+      ..addFlag(
+        'update-goldens',
+        help: 'Whether "matchesGoldenFile()" calls within your test methods '
+            'should update the golden files.',
+        negatable: false,
       );
   }
 
@@ -120,11 +126,13 @@ This command should be run from the root of your Flutter project.''',
         ? Random().nextInt(4294967295).toString()
         : randomOrderingSeed;
     final optimizePerformance = _argResults['optimization'] as bool;
+    final updateGoldens = _argResults['update-goldens'] as bool;
 
     if (isFlutterInstalled) {
       try {
         await _flutterTest(
-          optimizePerformance: optimizePerformance && _argResults.rest.isEmpty,
+          optimizePerformance:
+              optimizePerformance && _argResults.rest.isEmpty && !updateGoldens,
           recursive: recursive,
           progress: _logger.progress,
           stdout: _logger.write,
@@ -135,6 +143,7 @@ This command should be run from the root of your Flutter project.''',
           randomSeed: randomSeed,
           arguments: [
             if (excludeTags != null) ...['-x', excludeTags],
+            if (updateGoldens) '--update-goldens',
             '--no-pub',
             ..._argResults.rest,
           ],

test/src/commands/test/test_test.dart

@@ -23,6 +23,7 @@ const expectedTestUsage = [
       '''-x, --exclude-tags                    Run only tests that do not have the specified tags.\n'''
       '''    --min-coverage                    Whether to enforce a minimum coverage percentage.\n'''
       '''    --test-randomize-ordering-seed    The seed to randomize the execution order of test cases within test files.\n'''
+      '''    --update-goldens                  Whether "matchesGoldenFile()" calls within your test methods should update the golden files.\n'''
       '\n'
       'Run "very_good help" to see global options.'
 ];
@@ -89,6 +90,7 @@ void main() {
       ).thenAnswer((_) async {});
       when<dynamic>(() => argResults['recursive']).thenReturn(false);
       when<dynamic>(() => argResults['coverage']).thenReturn(false);
+      when<dynamic>(() => argResults['update-goldens']).thenReturn(false);
       when<dynamic>(() => argResults['optimization']).thenReturn(true);
       when(() => argResults.rest).thenReturn([]);
     });
@@ -180,6 +182,20 @@ void main() {
       ).called(1);
     });
 
+    test('completes normally --update-goldens', () async {
+      when<dynamic>(() => argResults['update-goldens']).thenReturn(true);
+      final result = await testCommand.run();
+      expect(result, equals(ExitCode.success.code));
+      verify(
+        () => flutterTest(
+          arguments: ['--update-goldens', ...defaultArguments],
+          progress: logger.progress,
+          stdout: logger.write,
+          stderr: logger.err,
+        ),
+      ).called(1);
+    });
+
     test('completes normally --test-randomize-ordering-seed random', () async {
       when<dynamic>(
         () => argResults['test-randomize-ordering-seed'],