findPackageConfig()

pkgs/extension_discovery/CHANGELOG.md

@@ -2,6 +2,8 @@
 
 - Require Dart 3.4.
 - Update to the latest version of `package:dart_flutter_team_lints`.
+- Add `findPackageConfig()` allowing for automatic discovery of the
+  packageConfig based on a package directory.
 
 ## 2.0.0
 

pkgs/extension_discovery/lib/extension_discovery.dart

@@ -14,7 +14,7 @@ import 'src/package_config.dart';
 import 'src/registry.dart';
 import 'src/yaml_config_format.dart';
 
-export 'src/package_config.dart' show PackageConfigException;
+export 'src/package_config.dart' show PackageConfigException, findPackageConfig;
 
 /// Information about an extension for target package.
 final class Extension {

pkgs/extension_discovery/lib/src/package_config.dart

@@ -8,6 +8,32 @@ import 'expect_json.dart';
 typedef PackageConfigEntry = ({String name, Uri rootUri, Uri packageUri});
 typedef PackageConfig = List<PackageConfigEntry>;
 
+/// Searches in [packageDir] and all directories above for a
+/// `.dart_tool/package_config.json` file. Returns the Uri of that file if
+/// found.
+///
+/// Returns `null` if no file was found.
+Uri? findPackageConfig(Uri packageDir) {
+  if (!packageDir.isScheme('file')) {
+    throw ArgumentError(
+      'Expected [packageDir] to be a file URI, got $packageDir',
+    );
+  }
+  if (!packageDir.path.endsWith('/')) {
+    packageDir = packageDir.replace(path: '${packageDir.path}/');
+  }
+  while (true) {
+    final packageConfigCandidate =
+        packageDir.resolve('.dart_tool/package_config.json');
+    if (File.fromUri(packageConfigCandidate).existsSync()) {
+      return packageConfigCandidate;
+    }
+    final next = packageDir.resolve('..');
+    if (next == packageDir) return null;
+    packageDir = next;
+  }
+}
+
 /// Load list of packages and associated URIs from the
 /// `.dart_tool/package_config.json` file in [packageConfigFile].
 Future<PackageConfig> loadPackageConfig(

pkgs/extension_discovery/test/find_extensions_test.dart

@@ -347,60 +347,4 @@ writtenAsYaml: true
       );
     }
   });
-
-  test('finds extensions in a workspace with `packageDir`', () async {
-    final pkgLibDir = await Isolate.resolvePackageUri(
-      Uri.parse('package:extension_discovery/'),
-    );
-    final pkgDir = pkgLibDir!.resolve('..');
-
-    await d.dir('workspace', [
-      d.pubspec({
-        'name': '_',
-        'environment': {'sdk': '^3.5.0'},
-        'workspace': ['myapp/'],
-      }),
-      d.dir('myapp', [
-        d.pubspec({
-          'name': 'myapp',
-          'dependencies': {
-            'extension_discovery': {'path': pkgDir.toFilePath()},
-            'foo': {'path': '../../foo'},
-          },
-          'environment': {'sdk': '^3.5.0'},
-          'resolution': 'workspace'
-        })
-      ])
-    ]).create();
-
-    await d.dir('foo', [
-      d.pubspec({
-        'name': 'foo',
-        'environment': {'sdk': '^3.0.0'},
-      }),
-      // It has a config.yaml for myapp
-      d.dir('extension/myapp', [
-        d.json('config.yaml', {'fromFoo': true}),
-      ]),
-    ]).create();
-
-    // Get dependencies
-    await d.dartPubGet(d.path('workspace'));
-    final [extension] = await findExtensions(
-      'myapp',
-      packageRootDir: d.fileUri('workspace/myapp'),
-    );
-    expect(extension.config, {'fromFoo': true});
-    expect(extension.package, 'foo');
-    expect(extension.rootUri, d.fileUri('foo/'));
-    expect(extension.packageUri, Uri.parse('lib/'));
-
-    // Check that there is a myapp.json cache file
-    await d
-        .file(
-          'workspace/.dart_tool/extension_discovery/myapp.json',
-          isNotEmpty,
-        )
-        .validate();
-  });
 }

pkgs/extension_discovery/test/package_config_test.dart

@@ -3,6 +3,7 @@
 // BSD-style license that can be found in the LICENSE file.
 
 import 'dart:convert' show jsonDecode, jsonEncode;
+import 'dart:math';
 
 import 'package:extension_discovery/src/package_config.dart';
 import 'package:test/test.dart';
@@ -159,4 +160,34 @@ void main() {
       throwsA(isA<PackageConfigException>()),
     );
   });
+
+  test('`findPackageConfig()`', () async {
+    await d.dir('workspace', [
+      d.dir('.dart_tool', [
+        d.file('package_config.json'),
+      ]),
+      d.dir('myapp', [])
+    ]).create();
+
+    expect(
+      findPackageConfig(d.fileUri('workspace')),
+      d.fileUri('workspace/.dart_tool/package_config.json'),
+    );
+    expect(
+      findPackageConfig(d.fileUri('workspace/')),
+      d.fileUri('workspace/.dart_tool/package_config.json'),
+    );
+    expect(
+      findPackageConfig(d.fileUri('workspace/myapp')),
+      d.fileUri('workspace/.dart_tool/package_config.json'),
+    );
+    expect(
+      findPackageConfig(d.fileUri('.')),
+      isNull,
+    );
+    expect(
+      findPackageConfig(d.fileUri('foo')),
+      isNull,
+    );
+  });
 }