add tests to ensure the sdk is well-formed (#41408)

add tests to ensure the sdk is well-formed

packages/flutter_tools/test/general.shard/dart/sdk_validation_test.dart

+// Copyright 2019 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'dart:async';
+
+import 'package:flutter_tools/src/base/file_system.dart';
+import 'package:flutter_tools/src/cache.dart';
+import 'package:flutter_tools/src/dart/analysis.dart';
+import 'package:flutter_tools/src/dart/pub.dart';
+import 'package:flutter_tools/src/dart/sdk.dart';
+import 'package:meta/meta.dart';
+
+import '../../src/common.dart';
+import '../../src/context.dart';
+
+void main() {
+  group('sdk validation', () {
+    AnalysisServer server;
+    Directory tempDir;
+
+    setUpAll(() {
+      Cache.disableLocking();
+      tempDir =
+          fs.systemTempDirectory.createTempSync('sdk_validation_test').absolute;
+    });
+
+    tearDownAll(() {
+      Cache.enableLocking();
+      tryToDelete(tempDir);
+      return server?.dispose();
+    });
+
+    testUsingContext('contains dart:ui', () async {
+      createSampleProject(tempDir, dartSource: '''
+import 'dart:ui' as ui;
+void main() {
+  // ignore: unnecessary_statements
+  ui.Window;
+}
+''');
+
+      await pubGet(context: PubContext.flutterTests, directory: tempDir.path);
+
+      server = AnalysisServer(dartSdkPath, <String>[tempDir.path]);
+
+      final int errorCount = await analyze(server);
+      expect(errorCount, 0);
+    });
+
+    testUsingContext('contains dart:html', () async {
+      createSampleProject(tempDir, dartSource: '''
+import 'dart:html' as html;
+void main() {
+  // ignore: unnecessary_statements
+  html.HttpStatus;
+}
+''');
+
+      await pubGet(context: PubContext.flutterTests, directory: tempDir.path);
+
+      server = AnalysisServer(dartSdkPath, <String>[tempDir.path]);
+
+      final int errorCount = await analyze(server);
+      expect(errorCount, 0);
+    });
+
+    testUsingContext('contains dart:js', () async {
+      createSampleProject(tempDir, dartSource: '''
+import 'dart:js' as js;
+void main() {
+  // ignore: unused_local_variable
+  var foo = js.allowInterop(null);
+}
+''');
+
+      await pubGet(context: PubContext.flutterTests, directory: tempDir.path);
+
+      server = AnalysisServer(dartSdkPath, <String>[tempDir.path]);
+
+      final int errorCount = await analyze(server);
+      expect(errorCount, 0);
+    });
+
+    testUsingContext('contains dart:js_util', () async {
+      createSampleProject(tempDir, dartSource: '''
+import 'dart:js_util' as js_util;
+void main() {
+  // ignore: unused_local_variable
+  var bar = js_util.jsify(null);
+}
+''');
+
+      await pubGet(context: PubContext.flutterTests, directory: tempDir.path);
+
+      server = AnalysisServer(dartSdkPath, <String>[tempDir.path]);
+
+      final int errorCount = await analyze(server);
+      expect(errorCount, 0);
+    });
+  });
+}
+
+void createSampleProject(Directory directory, {@required String dartSource}) {
+  final File pubspecFile =
+      fs.file(fs.path.join(directory.path, 'pubspec.yaml'));
+  pubspecFile.writeAsStringSync('''
+name: foo_project
+dependencies:
+  flutter:
+    sdk: flutter
+''');
+
+  final File dartFile =
+      fs.file(fs.path.join(directory.path, 'lib', 'main.dart'));
+  dartFile.parent.createSync();
+  dartFile.writeAsStringSync(dartSource);
+}
+
+Future<int> analyze(AnalysisServer server, {bool printErrors = true}) async {
+  int errorCount = 0;
+  final Future<bool> onDone =
+      server.onAnalyzing.where((bool analyzing) => analyzing == false).first;
+  server.onErrors.listen((FileAnalysisErrors errors) {
+    if (printErrors) {
+      for (AnalysisError error in errors.errors) {
+        print(error.toString().trim());
+      }
+    }
+    errorCount += errors.errors.length;
+  });
+
+  await server.start();
+  await onDone;
+
+  return errorCount;
+}