feat(test): add --dart-define (#492)

lib/src/commands/test/test.dart

@@ -92,6 +92,15 @@ class TestCommand extends Command<int> {
         help: 'Whether "matchesGoldenFile()" calls within your test methods '
             'should update the golden files.',
         negatable: false,
+      )
+      ..addMultiOption(
+        'dart-define',
+        help: 'Additional key-value pairs that will be available as constants '
+            'from the String.fromEnvironment, bool.fromEnvironment, '
+            'int.fromEnvironment, and double.fromEnvironment constructors. '
+            'Multiple defines can be passed by repeating '
+            '"--dart-define" multiple times.',
+        valueHelp: 'foo=bar',
       );
   }
 
@@ -142,6 +151,7 @@ This command should be run from the root of your Flutter project.''',
         : randomOrderingSeed;
     final optimizePerformance = _argResults['optimization'] as bool;
     final updateGoldens = _argResults['update-goldens'] as bool;
+    final dartDefine = _argResults['dart-define'] as List<String>?;
 
     if (isFlutterInstalled) {
       try {
@@ -160,6 +170,8 @@ This command should be run from the root of your Flutter project.''',
             if (excludeTags != null) ...['-x', excludeTags],
             if (tags != null) ...['-t', tags],
             if (updateGoldens) '--update-goldens',
+            if (dartDefine != null)
+              for (final value in dartDefine) '--dart-define=$value',
             ...['-j', concurrency],
             '--no-pub',
             ..._argResults.rest,

test/src/commands/test/test_test.dart

@@ -19,15 +19,16 @@ const expectedTestUsage = [
       '''    --coverage                        Whether to collect coverage information.\n'''
       '''-r, --recursive                       Run tests recursively for all nested packages.\n'''
       '''    --[no-]optimization               Whether to apply optimizations for test performance.\n'''
-      '                                      (defaults to on)\n'
+      '''                                      (defaults to on)\n'''
       '''-j, --concurrency                     The number of concurrent test suites run.\n'''
-      '                                      (defaults to "4")\n'
+      '''                                      (defaults to "4")\n'''
       '''-t, --tags                            Run only tests associated with the specified tags.\n'''
       '''    --exclude-coverage                A glob which will be used to exclude files that match from the coverage.\n'''
       '''-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'''
+      '''    --dart-define=<foo=bar>           Additional key-value pairs that will be available as constants from the String.fromEnvironment, bool.fromEnvironment, int.fromEnvironment, and double.fromEnvironment constructors. Multiple defines can be passed by repeating "--dart-define" multiple times.\n'''
       '\n'
       'Run "very_good help" to see global options.'
 ];
@@ -451,5 +452,26 @@ void main() {
       ).called(1);
       verify(() => logger.err('$exception')).called(1);
     });
+
+    test('completes normally --dart-define', () async {
+      when<dynamic>(
+        () => argResults['dart-define'],
+      ).thenReturn(['FOO=bar', 'X=42']);
+      final result = await testCommand.run();
+      expect(result, equals(ExitCode.success.code));
+      verify(
+        () => flutterTest(
+          optimizePerformance: true,
+          arguments: [
+            '--dart-define=FOO=bar',
+            '--dart-define=X=42',
+            ...defaultArguments,
+          ],
+          logger: logger,
+          stdout: logger.write,
+          stderr: logger.err,
+        ),
+      ).called(1);
+    });
   });
 }