feat(test): add --coverage and --min coverage options (#305)

Author: erickzanardo

README.md

@@ -155,8 +155,10 @@ very_good test -r
 Run tests in a Dart or Flutter project.
 
 Usage: very_good test [arguments]
--h, --help         Print this usage information.
--r, --recursive    Run tests recursively for all nested packages.
+-h, --help            Print this usage information.
+-r, --recursive       Run tests recursively for all nested packages.
+    --coverage        Whether to collect coverage information.
+    --min-coverage    Whether to enforce a minimum coverage percentage.
 
 Run "very_good help" to see global options.
 ```

lib/src/cli/cli.dart

@@ -1,5 +1,6 @@
 import 'dart:async';
 
+import 'package:lcov_parser/lcov_parser.dart';
 import 'package:mason/mason.dart';
 import 'package:path/path.dart' as p;
 import 'package:universal_io/io.dart';

lib/src/cli/flutter_cli.dart

@@ -4,6 +4,49 @@ part of 'cli.dart';
 /// is executed without a `pubspec.yaml`.
 class PubspecNotFound implements Exception {}
 
+/// {@template coverage_not_met}
+/// Thrown when `flutter test ---coverage --min-coverage`
+/// does not meet the provided minimum coverage threshold.
+/// {@endtemplate}
+class MinCoverageNotMet implements Exception {
+  /// {@macro coverage_not_met}
+  const MinCoverageNotMet(this.coverage);
+
+  /// The measured coverage percentage (total hits / total found * 100).
+  final double coverage;
+}
+
+/// Thrown when `flutter test ---coverage --min-coverage value`
+/// does not generate the coverage file within the timeout threshold.
+class GenerateCoverageTimeout implements Exception {
+  @override
+  String toString() => 'Timed out waiting for coverage to be generated.';
+}
+
+class _CoverageMetrics {
+  const _CoverageMetrics._({this.totalHits = 0, this.totalFound = 0});
+
+  /// Generate coverage metrics from a list of lcov records.
+  factory _CoverageMetrics.fromLcovRecords(List<Record> records) {
+    return records.fold<_CoverageMetrics>(
+      const _CoverageMetrics._(),
+      (current, record) {
+        final found = record.lines?.found ?? 0;
+        final hit = record.lines?.hit ?? 0;
+        return _CoverageMetrics._(
+          totalFound: current.totalFound + found,
+          totalHits: current.totalHits + hit,
+        );
+      },
+    );
+  }
+
+  final int totalHits;
+  final int totalFound;
+
+  double get percentage => totalFound < 1 ? 0 : (totalHits / totalFound * 100);
+}
+
 /// Flutter CLI
 class Flutter {
   /// Determine whether flutter is installed.
@@ -62,22 +105,40 @@ class Flutter {
   static Future<void> test({
     String cwd = '.',
     bool recursive = false,
+    bool collectCoverage = false,
+    double? minCoverage,
     void Function(String)? stdout,
     void Function(String)? stderr,
-  }) {
-    return _runCommand(
+  }) async {
+    final lcovPath = p.join(cwd, 'coverage', 'lcov.info');
+    final lcovFile = File(lcovPath);
+
+    if (collectCoverage && lcovFile.existsSync()) {
+      await lcovFile.delete();
+    }
+
+    await _runCommand(
       cmd: (cwd) {
         void noop(String? _) {}
         stdout?.call('Running "flutter test" in $cwd...\n');
         return _flutterTest(
           cwd: cwd,
+          collectCoverage: collectCoverage,
           stdout: stdout ?? noop,
           stderr: stderr ?? noop,
         );
       },
       cwd: cwd,
       recursive: recursive,
     );
+
+    if (collectCoverage) await lcovFile.ensureCreated();
+    if (minCoverage != null) {
+      final records = await Parser.parse(lcovPath);
+      final coverageMetrics = _CoverageMetrics.fromLcovRecords(records);
+      final coverage = coverageMetrics.percentage;
+      if (coverage < minCoverage) throw MinCoverageNotMet(coverage);
+    }
   }
 }
 
@@ -110,6 +171,7 @@ Future<void> _runCommand<T>({
 
 Future<void> _flutterTest({
   String cwd = '.',
+  bool collectCoverage = false,
   required void Function(String) stdout,
   required void Function(String) stderr,
 }) {
@@ -142,7 +204,13 @@ Future<void> _flutterTest({
     },
   );
 
-  flutterTest(workingDirectory: cwd, runInShell: true).listen(
+  flutterTest(
+    workingDirectory: cwd,
+    arguments: [
+      if (collectCoverage) '--coverage',
+    ],
+    runInShell: true,
+  ).listen(
     (event) {
       if (event.shouldCancelTimer()) timerSubscription.cancel();
       if (event is SuiteTestEvent) suites[event.suite.id] = event.suite;
@@ -217,6 +285,20 @@ final int _lineLength = () {
   }
 }();
 
+extension on File {
+  Future<void> ensureCreated({
+    Duration timeout = const Duration(seconds: 1),
+    Duration interval = const Duration(milliseconds: 50),
+  }) async {
+    var elapsedTime = Duration.zero;
+    while (!existsSync()) {
+      await Future<void>.delayed(interval);
+      elapsedTime += interval;
+      if (elapsedTime >= timeout) throw GenerateCoverageTimeout();
+    }
+  }
+}
+
 extension on TestEvent {
   bool shouldCancelTimer() {
     final event = this;

lib/src/commands/test.dart

@@ -12,12 +12,22 @@ import 'package:very_good_cli/src/cli/cli.dart';
 class TestCommand extends Command<int> {
   /// {@macro test_command}
   TestCommand({Logger? logger}) : _logger = logger ?? Logger() {
-    argParser.addFlag(
-      'recursive',
-      abbr: 'r',
-      help: 'Run tests recursively for all nested packages.',
-      negatable: false,
-    );
+    argParser
+      ..addFlag(
+        'recursive',
+        abbr: 'r',
+        help: 'Run tests recursively for all nested packages.',
+        negatable: false,
+      )
+      ..addFlag(
+        'coverage',
+        help: 'Whether to collect coverage information.',
+        negatable: false,
+      )
+      ..addOption(
+        'min-coverage',
+        help: 'Whether to enforce a minimum coverage percentage.',
+      );
   }
 
   final Logger _logger;
@@ -43,6 +53,10 @@ class TestCommand extends Command<int> {
     final recursive = _argResults['recursive'] as bool;
     final target = _argResults.rest.length == 1 ? _argResults.rest[0] : '.';
     final targetPath = path.normalize(Directory(target).absolute.path);
+    final collectCoverage = _argResults['coverage'] as bool;
+    final minCoverage = double.tryParse(
+      _argResults['min-coverage'] as String? ?? '',
+    );
     final isFlutterInstalled = await Flutter.installed();
     if (isFlutterInstalled) {
       try {
@@ -51,10 +65,17 @@ class TestCommand extends Command<int> {
           recursive: recursive,
           stdout: _logger.write,
           stderr: _logger.err,
+          collectCoverage: collectCoverage,
+          minCoverage: minCoverage,
         );
       } on PubspecNotFound catch (_) {
         _logger.err('Could not find a pubspec.yaml in $targetPath');
         return ExitCode.noInput.code;
+      } on MinCoverageNotMet catch (e) {
+        _logger.err(
+          '''Expected coverage >= ${minCoverage!.toStringAsFixed(2)}% but actual is ${e.coverage.toStringAsFixed(2)}%.''',
+        );
+        return ExitCode.unavailable.code;
       } catch (error) {
         _logger.err('$error');
         return ExitCode.unavailable.code;

pubspec.yaml

@@ -8,6 +8,7 @@ environment:
 
 dependencies:
   args: ^2.1.0
+  lcov_parser: ^0.1.2
   mason: ">=0.1.0-dev.9 <0.1.0-dev.10"
   mason_logger: ^0.1.0-dev.6
   meta: ^1.3.0