fix: support bootstrapping Flutter example packages (#428)

packages/melos/lib/src/commands/bootstrap.dart

@@ -71,12 +71,35 @@ mixin _BootstrapMixin on _CleanMixin {
       );
     }
 
-    await Stream.fromIterable(workspace.filteredPackages.values).parallel(
+    final filteredPackages = workspace.filteredPackages.values;
+
+    await Stream.fromIterable(filteredPackages).parallel(
       (package) async {
+        if (package.isExample) {
+          final enclosingPackage = package.enclosingPackage!;
+          if (enclosingPackage.isFlutterPackage &&
+              filteredPackages.contains(enclosingPackage)) {
+            // This package will be bootstrapped as part of bootstrapping
+            // the enclosing package.
+            return;
+          }
+        }
+
+        final bootstrappedPackages = [package];
         await _generatePubspecOverrides(workspace, package);
+        if (package.isFlutterPackage) {
+          final example = package.examplePackage;
+          if (example != null && filteredPackages.contains(example)) {
+            // The flutter tool bootstraps the example package as part of
+            // bootstrapping the enclosing package, so we need to generate
+            // the pubspec overrides for the example package as well.
+            await _generatePubspecOverrides(workspace, example);
+            bootstrappedPackages.add(example);
+          }
+        }
         await _runPubGetForPackage(workspace, package);
 
-        _logBootstrapSuccess(package);
+        bootstrappedPackages.forEach(_logBootstrapSuccess);
       },
       parallelism: workspace.config.commands.bootstrap.runPubGetInParallel &&
               workspace.canRunPubGetConcurrently

packages/melos/lib/src/package.dart

@@ -23,7 +23,6 @@ import 'dart:io';
 import 'package:collection/collection.dart';
 import 'package:glob/glob.dart';
 import 'package:meta/meta.dart';
-import 'package:path/path.dart';
 import 'package:path/path.dart' as p;
 import 'package:pool/pool.dart';
 import 'package:pub_semver/pub_semver.dart';
@@ -524,7 +523,7 @@ class PackageMap {
       late final isIncluded = packages.any((glob) => glob.matches(path)) &&
           !ignore.any((glob) => glob.matches(path));
 
-      if (entity is File && basename(path) == 'pubspec.yaml' && isIncluded) {
+      if (entity is File && p.basename(path) == 'pubspec.yaml' && isIncluded) {
         final resolvedPath = await entity.resolveSymbolicLinks();
         pubspecsByResolvedPath[resolvedPath] = entity;
       } else if (entity is Directory &&
@@ -645,7 +644,7 @@ extension on Iterable<Package> {
     return where((package) {
       return directoryPaths.every((dirExistsPath) {
         // TODO(rrousselGit): should support environment variables
-        return dirExists(join(package.path, dirExistsPath));
+        return dirExists(p.join(package.path, dirExistsPath));
       });
     });
   }
@@ -662,7 +661,7 @@ extension on Iterable<Package> {
         final expandedFileExistsPath =
             fileExistsPath.replaceAll(r'$MELOS_PACKAGE_NAME', package.name);
 
-        return fileExists(join(package.path, expandedFileExistsPath));
+        return fileExists(p.join(package.path, expandedFileExistsPath));
       });
       return fileExistsMatched;
     });
@@ -831,7 +830,7 @@ class Package {
     required this.publishTo,
     required this.pubSpec,
   })  : _packageMap = packageMap,
-        assert(isAbsolute(path));
+        assert(p.isAbsolute(path));
 
   final Map<String, Package> _packageMap;
 
@@ -977,10 +976,10 @@ class Package {
   /// pubspec.lock.
   Future<void> linkPackages(MelosWorkspace workspace) async {
     final pluginTemporaryPath =
-        join(workspace.melosToolPath, pathRelativeToWorkspace);
+        p.join(workspace.melosToolPath, pathRelativeToWorkspace);
 
     await Future.forEach(generatedPubFilePaths, (String tempFilePath) async {
-      final fileToCopy = join(pluginTemporaryPath, tempFilePath);
+      final fileToCopy = p.join(pluginTemporaryPath, tempFilePath);
       if (!fileExists(fileToCopy)) {
         return;
       }
@@ -1012,13 +1011,37 @@ class Package {
           temporaryFileContents.replaceAll(melosToolPathRegExp, '');
 
       await writeTextFileAsync(
-        join(path, tempFilePath),
+        p.join(path, tempFilePath),
         temporaryFileContents,
         recursive: true,
       );
     });
   }
 
+  /// The example [Package] contained within this package, if any.
+  ///
+  /// A package is considered to be an example if it is located in the `example`
+  /// directory of the [enclosingPackage].
+  late final Package? examplePackage = () {
+    final examplePath = p.join(path, 'example');
+    return _packageMap.values
+        .firstWhereOrNull((package) => p.equals(package.path, examplePath));
+  }();
+
+  /// The [Package] that encloses this package, if any.
+  ///
+  /// A package is considered to be the enclosing package if this package is
+  /// located in a direct child directory of the enclosing package.
+  late final Package? enclosingPackage = () {
+    final enclosingPackagePath = p.dirname(path);
+    return _packageMap.values.firstWhereOrNull(
+      (package) => p.equals(package.path, enclosingPackagePath),
+    );
+  }();
+
+  /// Whether this package is an example package as defined by [examplePackage].
+  bool get isExample => enclosingPackage?.examplePackage == this;
+
   /// Returns whether this package is a Flutter app.
   ///
   /// This is determined by ensuring all the following conditions are met:
@@ -1034,7 +1057,7 @@ class Package {
     // Must not have a Flutter plugin definition in it's pubspec.yaml.
     if (pubSpec.flutter?.plugin != null) return false;
 
-    return fileExists(joinAll([path, 'lib', 'main.dart']));
+    return fileExists(p.join(path, 'lib', 'main.dart'));
   }
 
   bool get isAddToApp {
@@ -1113,7 +1136,7 @@ class Package {
   String? get javaPluginClassPath {
     if (androidPackage == null || androidPluginClass == null) return null;
 
-    final javaPluginClassPath = joinAll([
+    final javaPluginClassPath = p.joinAll([
       path,
       'android/src/main/java',
       ...androidPackage!.split('.'),
@@ -1127,7 +1150,7 @@ class Package {
   String? get kotlinPluginClassPath {
     if (androidPackage == null || androidPluginClass == null) return null;
 
-    final kotlinPluginClassPath = joinAll([
+    final kotlinPluginClassPath = p.joinAll([
       path,
       'android/src/main/kotlin',
       ...androidPackage!.split('.'),
@@ -1175,7 +1198,7 @@ class Package {
   }
 
   /// Returns whether this package contains a test directory.
-  bool get hasTests => dirExists(joinAll([path, 'test']));
+  bool get hasTests => dirExists(p.join(path, 'test'));
 
   bool _flutterAppSupportsPlatform(String platform) {
     assert(

packages/melos/test/commands/bootstrap_test.dart

@@ -259,7 +259,7 @@ Generating IntelliJ IDE files...
         config: config,
       );
 
-      await melos.bootstrap();
+      await runMelosBootstrap(melos, logger);
 
       final packageConfig = packageConfigForPackageAt(pkgA);
       expect(
@@ -348,7 +348,7 @@ Generating IntelliJ IDE files...
             config: config,
           );
 
-          await melos.bootstrap();
+          await runMelosBootstrap(melos, logger);
 
           final packageConfig = packageConfigForPackageAt(pkgA);
           expect(
@@ -361,6 +361,51 @@ Generating IntelliJ IDE files...
         skip: !isPubspecOverridesSupported(),
       );
 
+      test('bootstrap flutter example packages', () async {
+        final workspaceDir = createTemporaryWorkspaceDirectory(
+          configBuilder: (path) => MelosWorkspaceConfig.fallback(
+            path: path,
+            usePubspecOverrides: true,
+          ),
+        );
+
+        await createProject(
+          workspaceDir,
+          const PubSpec(
+            name: 'a',
+            dependencies: {
+              'flutter': SdkReference('flutter'),
+            },
+          ),
+          path: 'packages/a',
+        );
+
+        final examplePkg = await createProject(
+          workspaceDir,
+          PubSpec(
+            name: 'example',
+            dependencies: {
+              'a': HostedReference(VersionConstraint.any),
+            },
+          ),
+          path: 'packages/a/example',
+        );
+
+        final logger = TestLogger();
+        final config = await MelosWorkspaceConfig.fromDirectory(workspaceDir);
+        final melos = Melos(
+          logger: logger,
+          config: config,
+        );
+
+        await runMelosBootstrap(melos, logger);
+
+        final examplePkgConfig = packageConfigForPackageAt(examplePkg);
+        final aPkgDependencyConfig = examplePkgConfig.packages
+            .firstWhere((package) => package.name == 'a');
+        expect(aPkgDependencyConfig.rootUri, '../../');
+      });
+
       group('mergeMelosPubspecOverrides', () {
         void expectMergedMelosPubspecOverrides({
           required Map<String, String> melosDependencyOverrides,
@@ -628,10 +673,6 @@ Generating IntelliJ IDE files...
         ),
       );
     });
-
-    test('can disable IDE generation using melos config', () {}, skip: true);
-
-    test('can supports package filter', () {}, skip: true);
   });
 }