Add librariesSpec arg to FronendServerClient.start (#2855)

Author: schultek

frontend_server_client/CHANGELOG.md

@@ -2,6 +2,7 @@
 
 - Update Dart SDK constraint to `^3.10.0`.
 - Allow package_config `3.x.x`.
+- Add `librariesSpec` parameter to `FrontendServerClient.start()`.
 - Use `sdkRoot` to resolve Dart executable and frontend server snapshot locations when provided.
 
 ## 4.0.0

frontend_server_client/lib/src/dartdevc_frontend_server_client.dart

@@ -67,6 +67,7 @@ class DartDevcFrontendServerClient implements FrontendServerClient {
     String fileSystemScheme =
         'org-dartlang-root', // Custom scheme for virtual `fileSystemRoots`.
     String? frontendServerPath, // Defaults to the snapshot in the sdk.
+    String? librariesSpec,
     String packagesJson = '.dart_tool/package_config.json',
     String? platformKernel, // Defaults to the dartdevc platform from the sdk.
     String? sdkRoot, // Defaults to the current SDK root.
@@ -83,6 +84,7 @@ class DartDevcFrontendServerClient implements FrontendServerClient {
       fileSystemRoots: fileSystemRoots,
       fileSystemScheme: fileSystemScheme,
       frontendServerPath: frontendServerPath,
+      librariesSpec: librariesSpec,
       packagesJson: packagesJson,
       sdkRoot: sdkRoot,
       target: 'dartdevc',

frontend_server_client/lib/src/frontend_server_client.dart

@@ -39,6 +39,9 @@ class FrontendServerClient {
   /// The [entrypoint] and [packagesJson] may be a relative path or any uri
   /// supported by the frontend server.
   ///
+  /// The [librariesSpec] argument can be provided to specify a custom libraries
+  /// specification file.
+  ///
   /// The [outputDillPath] determines where the primary output should be, and
   /// some targets may output additional files based on that file name (by
   /// adding file extensions for instance).
@@ -63,6 +66,7 @@ class FrontendServerClient {
     String fileSystemScheme =
         'org-dartlang-root', // Custom scheme for virtual `fileSystemRoots`.
     String? frontendServerPath, // Defaults to the snapshot in the sdk.
+    String? librariesSpec,
     String packagesJson = '.dart_tool/package_config.json',
     String? sdkRoot, // Defaults to the current SDK root.
     String target = 'vm', // The kernel target type.
@@ -84,6 +88,7 @@ class FrontendServerClient {
       '--output-dill',
       outputDillPath,
       '--packages=$packagesJson',
+      if (librariesSpec != null) ...['--libraries-spec', librariesSpec],
       if (enableHttpUris) '--enable-http-uris',
       '--incremental',
       if (verbose) '--verbose',

frontend_server_client/test/frontend_server_client_test.dart

@@ -337,6 +337,58 @@ void main() {
     expect(processResult.stdout, startsWith('goodbye world'));
     expect(processResult.exitCode, 0);
   });
+
+  test('can support custom librariesSpec', () async {
+    final defaultLibrariesJson = File(p.join(sdkDir, 'lib', 'libraries.json'));
+    final libraries =
+        jsonDecode(defaultLibrariesJson.readAsStringSync())
+            as Map<String, Object?>;
+
+    // Create the custom library file
+    final customLibFile = File(p.join(packageRoot, 'bin', 'custom_lib.dart'));
+    await customLibFile.writeAsString('void hello() => print("custom!");');
+
+    if (libraries['vm_common'] case {
+      'libraries': final Map<String, Object?> libs,
+    }) {
+      libs['custom_lib'] = {'uri': customLibFile.absolute.uri.toString()};
+    }
+
+    final customLibrariesJsonFile = File(p.join(packageRoot, 'libraries.json'));
+    await customLibrariesJsonFile.writeAsString(jsonEncode(libraries));
+
+    final entrypoint = p.join(packageRoot, 'bin', 'main_custom.dart');
+    await File(entrypoint).writeAsString('''
+      import 'dart:custom_lib';
+      void main() {
+        hello();
+      }
+    ''');
+
+    client = await FrontendServerClient.start(
+      entrypoint,
+      p.join(packageRoot, 'out_custom.dill'),
+      vmPlatformDill,
+      packagesJson: packagesJsonPath,
+      librariesSpec: customLibrariesJsonFile.uri.toString(),
+    );
+    var result = await client!.compile();
+    client!.accept();
+    expect(result.errorCount, 0);
+    expect(result.dillOutput, isNotNull);
+    await client!.shutdown();
+
+    // Without librariesSpec, compiling the same entrypoint should fail
+    client = await FrontendServerClient.start(
+      entrypoint,
+      p.join(packageRoot, 'out_custom_fail.dill'),
+      vmPlatformDill,
+      packagesJson: packagesJsonPath,
+    );
+    result = await client!.compile();
+    client!.accept();
+    expect(result.errorCount, greaterThan(0));
+  });
 }
 
 Future<Isolate> waitForIsolatesAndResume(VmService vmService) async {