fix: coverage on dart test

lib/src/cli/cli.dart

@@ -1,6 +1,7 @@
 import 'dart:async';
 import 'dart:math';
 import 'package:collection/collection.dart';
+import 'package:coverage/coverage.dart' as coverage;
 import 'package:glob/glob.dart';
 import 'package:lcov_parser/lcov_parser.dart';
 import 'package:mason/mason.dart';

lib/src/cli/test_cli_runner.dart

@@ -142,6 +142,7 @@ class TestCLIRunner {
                 cwd: cwd,
                 collectCoverage: collectCoverage,
                 testRunner: testRunner,
+                testType: testType,
                 arguments: [
                   ...?arguments,
                   if (randomSeed != null) ...[
@@ -158,6 +159,38 @@ class TestCLIRunner {
                   await _cleanupOptimizerFile(cwd);
                 }
 
+                // Dart don't directly generate lcov files, so we need
+                // to read the json that is generates and convert it to lcov.
+                if (testType == TestRunType.dart && collectCoverage) {
+                  final files = _dartCoverageFilesToProcess(
+                    p.join(cwd, 'coverage'),
+                  );
+
+                  final packagesPath = p.join(
+                    '.dart_tool',
+                    'package_config.json',
+                  );
+                  final hitmap = await coverage.HitMap.parseFiles(
+                    files,
+                    packagePath: packagesPath,
+                  );
+
+                  final resolver = await coverage.Resolver.create(
+                    packagesPath: packagesPath,
+                    packagePath: packagesPath,
+                  );
+
+                  final output = hitmap.formatLcov(
+                    resolver,
+                    reportOn: ['lib'],
+                    basePath: cwd,
+                  );
+
+                  // Write the lcov output to the file.
+                  await lcovFile.create(recursive: true);
+                  await lcovFile.writeAsString(output);
+                }
+
                 if (collectCoverage) {
                   assert(
                     lcovFile.existsSync(),
@@ -214,12 +247,21 @@ class TestCLIRunner {
       '''Expected coverage >= ${minCoverage.toStringAsFixed(decimalPlaces)}% but actual is ${e.coverage.toStringAsFixed(decimalPlaces)}%.''',
     );
   }
+
+  static List<File> _dartCoverageFilesToProcess(String absPath) {
+    return Directory(absPath)
+        .listSync(recursive: true)
+        .whereType<File>()
+        .where((e) => e.path.endsWith('.json'))
+        .toList();
+  }
 }
 
 Future<int> _testCommand({
   required void Function(String) stdout,
   required void Function(String) stderr,
   required VeryGoodTestRunner testRunner,
+  required TestRunType testType,
   String cwd = '.',
   bool collectCoverage = false,
   List<String>? arguments,
@@ -273,7 +315,13 @@ Future<int> _testCommand({
   subscription =
       testRunner(
         workingDirectory: cwd,
-        arguments: [if (collectCoverage) '--coverage', ...?arguments],
+        arguments: [
+          if (collectCoverage)
+            testType == TestRunType.flutter
+                ? '--coverage'
+                : '--coverage=coverage',
+          ...?arguments,
+        ],
         runInShell: true,
       ).listen(
         (event) {

pubspec.yaml

@@ -14,6 +14,7 @@ dependencies:
   args: ^2.6.0
   cli_completion: ^0.5.1
   collection: ^1.19.0
+  coverage: ^1.15.0
   equatable: ^2.0.5
   glob: ^2.1.2
   lcov_parser: ^0.1.2

test/src/cli/test_runner_cli_test.dart

@@ -684,7 +684,7 @@ void main() {
         );
       });
 
-      test('runs tests w/coverage', () async {
+      test('runs flutter tests w/coverage', () async {
         final tempDirectory = Directory.systemTemp.createTempSync();
         addTearDown(() => tempDirectory.deleteSync(recursive: true));
 
@@ -728,6 +728,50 @@ void main() {
         expect(testRunnerArgs, equals(['--coverage']));
       });
 
+      test('runs flutter tests w/coverage', () async {
+        final tempDirectory = Directory.systemTemp.createTempSync();
+        addTearDown(() => tempDirectory.deleteSync(recursive: true));
+
+        final lcovFile = File(
+          p.join(tempDirectory.path, 'coverage', 'lcov.info'),
+        );
+        File(p.join(tempDirectory.path, 'pubspec.yaml')).createSync();
+        Directory(p.join(tempDirectory.path, 'test')).createSync();
+        lcovFile.createSync(recursive: true);
+
+        await expectLater(
+          TestCLIRunner.test(
+            testType: TestRunType.dart,
+            cwd: tempDirectory.path,
+            collectCoverage: true,
+            stdout: stdoutLogs.add,
+            stderr: stderrLogs.add,
+            overrideTestRunner: testRunner(
+              Stream.fromIterable(
+                [
+                  const DoneTestEvent(success: true, time: 0),
+                  const ExitTestEvent(exitCode: 0, time: 0),
+                ],
+              ),
+              onStart: () {
+                expect(lcovFile.existsSync(), isFalse);
+                lcovFile.createSync(recursive: true);
+              },
+            ),
+            logger: logger,
+          ),
+          completion(equals([ExitCode.success.code])),
+        );
+        expect(
+          stdoutLogs,
+          equals([
+            'Running "dart test" in . ...\n',
+            contains('All tests passed!'),
+          ]),
+        );
+        expect(testRunnerArgs, equals(['--coverage=coverage']));
+      });
+
       test('runs tests w/coverage + min-coverage 100 (pass)', () async {
         final tempDirectory = Directory.systemTemp.createTempSync();
         addTearDown(() => tempDirectory.deleteSync(recursive: true));