Felt add integration (flutter/engine#17190)

* adding arguments to felt for running different type of tests

* adding test type enums to felt

* more changes to felt for testing branches

* more additions to code

* more changes to felt

* adding code for cloning web_drivers

* validating test directories. running the integration tests. update the readme file partially

* Removing todo lists used for development

* addressing reviewers comments

* remove unused imports

* addressing more reviewer comments

* addressing more reviewer comments

* addressing reviewer comments.

* addressing reviewer comments.

* fixing typos

* using chromedriverinstaller as a library. Fixing the commit number used from web_installers repo

* clean drivers directory after tests finish

* addressing more reviewer comments

* throwing all critical exceptions instead of logging and returning boolean flags

* adding todos for items we can do for making felt easier to use for local development

* do not run integration tests on CIs. Added an issue to the TODO.

* changing todo's with issues.

engine/src/flutter/lib/web_ui/dev/README.md

@@ -31,12 +31,24 @@ felt build [-w] -j 100
 If you are a Google employee, you can use an internal instance of Goma to parallelize your builds. Because Goma compiles code on remote servers, this option is effective even on low-powered laptops.
 
 ## Running web engine tests
-To run all tests on Chrome:
+To run all tests on Chrome. This will run both integration tests and the unit tests:
 
 ```
 felt test
 ```
 
+To run unit tests only:
+
+```
+felt test --unit-tests-only
+```
+
+To run integration tests only. For now these tests are only available on Chrome Desktop browsers.
+
+```
+felt test --integration-tests-only
+```
+
 To run tests on Firefox (this will work only on a Linux device):
 
 ```
@@ -55,7 +67,7 @@ To run tests on Safari use the following command. It works on MacOS devices and
 felt test --browser=safari
 ```
 
-To run tests on Windows Edge use the following command. It works on Windows devices and it uses the Edge installed on the OS. 
+To run tests on Windows Edge use the following command. It works on Windows devices and it uses the Edge installed on the OS.
 
 ```
 felt_windows.bat test --browser=edge

engine/src/flutter/lib/web_ui/dev/common.dart

@@ -27,6 +27,15 @@ class BrowserInstallerException implements Exception {
   String toString() => message;
 }
 
+class DriverException implements Exception {
+  DriverException(this.message);
+
+  final String message;
+
+  @override
+  String toString() => message;
+}
+
 abstract class PlatformBinding {
   static PlatformBinding get instance {
     if (_instance == null) {
@@ -77,11 +86,10 @@ class _WindowsBinding implements PlatformBinding {
   @override
   String getFirefoxDownloadUrl(String version) =>
       'https://download-installer.cdn.mozilla.net/pub/firefox/releases/${version}/win64/en-US/'
-          '${getFirefoxDownloadFilename(version)}';
+      '${getFirefoxDownloadFilename(version)}';
 
   @override
-  String getFirefoxDownloadFilename(String version) =>
-      'firefox-${version}.exe';
+  String getFirefoxDownloadFilename(String version) => 'firefox-${version}.exe';
 
   @override
   String getFirefoxExecutablePath(io.Directory versionDir) =>
@@ -117,7 +125,7 @@ class _LinuxBinding implements PlatformBinding {
   @override
   String getFirefoxDownloadUrl(String version) =>
       'https://download-installer.cdn.mozilla.net/pub/firefox/releases/${version}/linux-x86_64/en-US/'
-          '${getFirefoxDownloadFilename(version)}';
+      '${getFirefoxDownloadFilename(version)}';
 
   @override
   String getFirefoxDownloadFilename(String version) =>
@@ -161,16 +169,15 @@ class _MacBinding implements PlatformBinding {
 
   @override
   String getFirefoxDownloadUrl(String version) =>
-    'https://download-installer.cdn.mozilla.net/pub/firefox/releases/${version}/mac/en-US/'
-        '${getFirefoxDownloadFilename(version)}';
+      'https://download-installer.cdn.mozilla.net/pub/firefox/releases/${version}/mac/en-US/'
+      '${getFirefoxDownloadFilename(version)}';
 
   @override
-  String getFirefoxDownloadFilename(String version) =>
-      'Firefox ${version}.dmg';
+  String getFirefoxDownloadFilename(String version) => 'Firefox ${version}.dmg';
 
   @override
   String getFirefoxExecutablePath(io.Directory versionDir) =>
-    path.join(versionDir.path, 'Firefox.app','Contents','MacOS', 'firefox');
+      path.join(versionDir.path, 'Firefox.app', 'Contents', 'MacOS', 'firefox');
 
   @override
   String getFirefoxLatestVersionUrl() =>
@@ -243,3 +250,14 @@ class DevNull implements StringSink {
 }
 
 bool get isCirrus => io.Platform.environment['CIRRUS_CI'] == 'true';
+
+/// There might be proccesses started during the tests.
+///
+/// Use this list to store those Processes, for cleaning up before shutdown.
+final List<io.Process> processesToCleanUp = List<io.Process>();
+
+/// There might be temporary directories created during the tests.
+///
+/// Use this list to store those directories and for deleteing them before
+/// shutdown.
+final List<io.Directory> temporaryDirectories = List<io.Directory>();

engine/src/flutter/lib/web_ui/dev/environment.dart

@@ -22,6 +22,7 @@ class Environment {
     final io.Directory hostDebugUnoptDir = io.Directory(pathlib.join(outDir.path, 'host_debug_unopt'));
     final io.Directory dartSdkDir = io.Directory(pathlib.join(hostDebugUnoptDir.path, 'dart-sdk'));
     final io.Directory webUiRootDir = io.Directory(pathlib.join(engineSrcDir.path, 'flutter', 'lib', 'web_ui'));
+    final io.Directory integrationTestsDir = io.Directory(pathlib.join(engineSrcDir.path, 'flutter', 'e2etests', 'web'));
 
     for (io.Directory expectedDirectory in <io.Directory>[engineSrcDir, outDir, hostDebugUnoptDir, dartSdkDir, webUiRootDir]) {
       if (!expectedDirectory.existsSync()) {
@@ -34,6 +35,7 @@ class Environment {
       self: self,
       webUiRootDir: webUiRootDir,
       engineSrcDir: engineSrcDir,
+      integrationTestsDir: integrationTestsDir,
       outDir: outDir,
       hostDebugUnoptDir: hostDebugUnoptDir,
       dartSdkDir: dartSdkDir,
@@ -44,6 +46,7 @@ class Environment {
     this.self,
     this.webUiRootDir,
     this.engineSrcDir,
+    this.integrationTestsDir,
     this.outDir,
     this.hostDebugUnoptDir,
     this.dartSdkDir,
@@ -58,6 +61,9 @@ class Environment {
   /// Path to the engine's "src" directory.
   final io.Directory engineSrcDir;
 
+  /// Path to the web integration tests.
+  final io.Directory integrationTestsDir;
+
   /// Path to the engine's "out" directory.
   ///
   /// This is where you'll find the ninja output, such as the Dart SDK.

engine/src/flutter/lib/web_ui/dev/felt

@@ -56,9 +56,9 @@ install_deps() {
 KERNEL_NAME=`uname`
 if [[ $KERNEL_NAME == *"Darwin"* ]]
 then
-     echo "Running on MacOS. Increase the user limits"
-     ulimit -n 50000
-     ulimit -u 4096
+  echo "Running on MacOS. Increase the user limits"
+  ulimit -n 50000
+  ulimit -u 4096
 fi
 
 if [[ "$FELT_USE_SNAPSHOT" == "false" || "$FELT_USE_SNAPSHOT" == "0" ]]; then

engine/src/flutter/lib/web_ui/dev/felt.dart

@@ -9,6 +9,7 @@ import 'package:args/command_runner.dart';
 
 import 'build.dart';
 import 'clean.dart';
+import 'common.dart';
 import 'licenses.dart';
 import 'test_runner.dart';
 
@@ -41,12 +42,29 @@ void main(List<String> args) async {
     io.exit(64); // Exit code 64 indicates a usage error.
   } catch (e) {
     rethrow;
+  } finally {
+    _cleanup();
   }
 
   // Sometimes the Dart VM refuses to quit.
   io.exit(io.exitCode);
 }
 
+void _cleanup() {
+  // Cleanup remaining processes if any.
+  if (processesToCleanUp.length > 0) {
+    for (io.Process process in processesToCleanUp) {
+      process.kill();
+    }
+  }
+  // Delete temporary directories.
+  if (temporaryDirectories.length > 0) {
+    for (io.Directory directory in temporaryDirectories) {
+      directory.deleteSync(recursive: true);
+    }
+  }
+}
+
 void _listenToShutdownSignals() {
   io.ProcessSignal.sigint.watch().listen((_) {
     print('Received SIGINT. Shutting down.');

engine/src/flutter/lib/web_ui/dev/integration_tests_manager.dart

@@ -0,0 +1,350 @@
+// Copyright 2013 The Flutter 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:io' as io;
+import 'package:path/path.dart' as pathlib;
+import 'package:web_driver_installer/chrome_driver_installer.dart';
+
+import 'common.dart';
+import 'environment.dart';
+import 'utils.dart';
+
+class IntegrationTestsManager {
+  final String _browser;
+
+  /// Installation directory for browser's driver.
+  ///
+  /// Always re-install since driver can change frequently.
+  /// It usually changes with each the browser version changes.
+  /// A better solution would be installing the browser and the driver at the
+  /// same time.
+  // TODO(nurhan): change the web installers to install driver and the browser
+  // at the same time.
+  final io.Directory _browserDriverDir;
+
+  /// This is the parent directory for all drivers.
+  ///
+  /// This directory is saved to [temporaryDirectories] and deleted before
+  /// tests shutdown.
+  final io.Directory _drivers;
+
+  IntegrationTestsManager(this._browser)
+      : this._browserDriverDir = io.Directory(
+            pathlib.join(environment.webUiRootDir.path, 'drivers', _browser)),
+        this._drivers = io.Directory(
+            pathlib.join(environment.webUiRootDir.path, 'drivers'));
+
+  Future<bool> runTests() async {
+    if (_browser != 'chrome') {
+      print('WARNING: integration tests are only supported on chrome for now');
+      return false;
+    } else {
+      await prepareDriver();
+      // TODO(nurhan): https://github.com/flutter/flutter/issues/52987
+      return await _runTests();
+    }
+  }
+
+  void _cloneWebInstallers() async {
+    final int exitCode = await runProcess(
+      'git',
+      <String>[
+        'clone',
+        'https://github.com/flutter/web_installers.git',
+      ],
+      workingDirectory: _browserDriverDir.path,
+    );
+
+    if (exitCode != 0) {
+      io.stderr.writeln('ERROR: '
+          'Failed to clone web installers. Exited with exit code $exitCode');
+      throw DriverException('ERROR: '
+          'Failed to clone web installers. Exited with exit code $exitCode');
+    }
+  }
+
+  Future<bool> _runPubGet(String workingDirectory) async {
+    final String executable = isCirrus ? environment.pubExecutable : 'flutter';
+    final List<String> arguments = isCirrus
+        ? <String>[
+            'get',
+          ]
+        : <String>[
+            'pub',
+            'get',
+          ];
+    final int exitCode = await runProcess(
+      executable,
+      arguments,
+      workingDirectory: workingDirectory,
+    );
+
+    if (exitCode != 0) {
+      io.stderr.writeln(
+          'ERROR: Failed to run pub get. Exited with exit code $exitCode');
+      return false;
+    } else {
+      return true;
+    }
+  }
+
+  void _runDriver() async {
+    final int exitCode = await runProcess(
+      environment.dartExecutable,
+      <String>[
+        'lib/web_driver_installer.dart',
+        '${_browser}driver',
+        '--install-only',
+      ],
+      workingDirectory: pathlib.join(
+          _browserDriverDir.path, 'web_installers', 'packages', 'web_drivers'),
+    );
+
+    if (exitCode != 0) {
+      io.stderr.writeln(
+          'ERROR: Failed to run driver. Exited with exit code $exitCode');
+      throw DriverException(
+          'ERROR: Failed to run driver. Exited with exit code $exitCode');
+    }
+    startProcess(
+      './chromedriver/chromedriver',
+      ['--port=4444'],
+      workingDirectory: pathlib.join(
+          _browserDriverDir.path, 'web_installers', 'packages', 'web_drivers'),
+    );
+    print('INFO: Driver started');
+  }
+
+  void prepareDriver() async {
+    final io.Directory priorCurrentDirectory = io.Directory.current;
+    if (_browserDriverDir.existsSync()) {
+      _browserDriverDir.deleteSync(recursive: true);
+    }
+
+    _browserDriverDir.createSync(recursive: true);
+    temporaryDirectories.add(_drivers);
+
+    // TODO(nurhan): We currently need git clone for getting the driver lock
+    // file. Remove this after making changes in web_installers.
+    await _cloneWebInstallers();
+    // Change the directory to the driver_lock.yaml file's directory.
+    io.Directory.current = pathlib.join(
+        _browserDriverDir.path, 'web_installers', 'packages', 'web_drivers');
+    // Chrome is the only browser supporting integration tests for now.
+    ChromeDriverInstaller chromeDriverInstaller = ChromeDriverInstaller();
+    bool installation = await chromeDriverInstaller.install();
+
+    if (installation) {
+      io.Directory.current = priorCurrentDirectory;
+      await _runDriver();
+    } else {
+      throw DriverException('ERROR: Installing driver failed');
+    }
+  }
+
+  /// Runs all the web tests under e2e_tests/web.
+  Future<bool> _runTests() async {
+    // Only list the files under e2e_tests/web.
+    final List<io.FileSystemEntity> entities =
+        environment.integrationTestsDir.listSync(followLinks: false);
+
+    bool allTestsPassed = true;
+    for (io.FileSystemEntity e in entities) {
+      // The tests should be under this directories.
+      if (e is io.Directory) {
+        allTestsPassed = allTestsPassed && await _validateAndRunTests(e);
+      }
+    }
+    return allTestsPassed;
+  }
+
+  /// Run tests in a single directory under: e2e_tests/web.
+  ///
+  /// Run `flutter pub get` as the first step.
+  ///
+  /// Validate the directory before running the tests. Each directory is
+  /// expected to be a test project which includes a `pubspec.yaml` file
+  /// and a `test_driver` directory.
+  Future<bool> _validateAndRunTests(io.Directory directory) async {
+    _validateTestDirectory(directory);
+    await _runPubGet(directory.path);
+    final bool testResults = await _runTestsInDirectory(directory);
+    return testResults;
+  }
+
+  Future<bool> _runTestsInDirectory(io.Directory directory) async {
+    final io.Directory testDirectory =
+        io.Directory(pathlib.join(directory.path, 'test_driver'));
+    final List<io.FileSystemEntity> entities = testDirectory
+        .listSync(followLinks: false)
+        .whereType<io.File>()
+        .toList();
+
+    final List<String> e2eTestsToRun = List<String>();
+
+    // The following loops over the contents of the directory and saves an
+    // expected driver file name for each e2e test assuming any dart file
+    // not ending with `_test.dart` is an e2e test.
+    // Other files are not considered since developers can add files such as
+    // README.
+    for (io.File f in entities) {
+      final String basename = pathlib.basename(f.path);
+      if (!basename.contains('_test.dart') && basename.endsWith('.dart')) {
+        e2eTestsToRun.add(basename);
+      }
+    }
+
+    print(
+        'INFO: In project ${directory} ${e2eTestsToRun.length} tests to run.');
+
+    int numberOfPassedTests = 0;
+    int numberOfFailedTests = 0;
+    for (String fileName in e2eTestsToRun) {
+      final bool testResults =
+          await _runTestsInProfileMode(directory, fileName);
+      if (testResults) {
+        numberOfPassedTests++;
+      } else {
+        numberOfFailedTests++;
+      }
+    }
+    final int numberOfTestsRun = numberOfPassedTests + numberOfFailedTests;
+
+    print('INFO: ${numberOfTestsRun} tests run. ${numberOfPassedTests} passed '
+        'and ${numberOfFailedTests} failed.');
+    return numberOfFailedTests == 0;
+  }
+
+  Future<bool> _runTestsInProfileMode(
+      io.Directory directory, String testName) async {
+    final int exitCode = await runProcess(
+      'flutter',
+      <String>[
+        'drive',
+        '--target=test_driver/${testName}',
+        '-d',
+        'web-server',
+        '--profile',
+        '--browser-name=$_browser',
+        '--local-engine=host_debug_unopt',
+      ],
+      workingDirectory: directory.path,
+    );
+
+    if (exitCode != 0) {
+      final String statementToRun = 'flutter drive '
+          '--target=test_driver/${testName} -d web-server --profile '
+          '--browser-name=$_browser --local-engine=host_debug_unopt';
+      io.stderr
+          .writeln('ERROR: Failed to run test. Exited with exit code $exitCode'
+              '. Statement to run $testName locally use the following '
+              'command:\n\n$statementToRun');
+      return false;
+    } else {
+      return true;
+    }
+  }
+
+  /// Validate the directory has a `pubspec.yaml` file and a `test_driver`
+  /// directory.
+  ///
+  /// Also check the validity of files under `test_driver` directory calling
+  /// [_checkE2ETestsValidity] method.
+  void _validateTestDirectory(io.Directory directory) {
+    final List<io.FileSystemEntity> entities =
+        directory.listSync(followLinks: false);
+
+    // Whether the project has the pubspec.yaml file.
+    bool pubSpecFound = false;
+    // The test directory 'test_driver'.
+    io.Directory testDirectory = null;
+
+    for (io.FileSystemEntity e in entities) {
+      // The tests should be under this directories.
+      final String baseName = pathlib.basename(e.path);
+      if (e is io.Directory && baseName == 'test_driver') {
+        testDirectory = e;
+      }
+      if (e is io.File && baseName == 'pubspec.yaml') {
+        pubSpecFound = true;
+      }
+    }
+    if (!pubSpecFound) {
+      throw StateError('ERROR: pubspec.yaml file not found in the test project '
+          'in the directory ${directory.path}.');
+    }
+    if (testDirectory == null) {
+      throw StateError(
+          'ERROR: test_driver folder not found in the test project.'
+          'in the directory ${directory.path}.');
+    } else {
+      _checkE2ETestsValidity(testDirectory);
+    }
+  }
+
+  /// Checks if each e2e test file in the directory has a driver test
+  /// file to run it.
+  ///
+  /// Prints informative message to the developer if an error has found.
+  /// For each e2e test which has name {name}.dart there will be a driver
+  /// file which drives it. The driver file should be named:
+  /// {name}_test.dart
+  void _checkE2ETestsValidity(io.Directory testDirectory) {
+    final Iterable<io.Directory> directories =
+        testDirectory.listSync(followLinks: false).whereType<io.Directory>();
+
+    if (directories.length > 0) {
+      throw StateError('${testDirectory.path} directory should not contain '
+          'any sub-directories');
+    }
+
+    final Iterable<io.File> entities =
+        testDirectory.listSync(followLinks: false).whereType<io.File>();
+
+    final Set<String> expectedDriverFileNames = Set<String>();
+    final Set<String> foundDriverFileNames = Set<String>();
+    int numberOfTests = 0;
+
+    // The following loops over the contents of the directory and saves an
+    // expected driver file name for each e2e test assuming any file
+    // not ending with `_test.dart` is an e2e test.
+    for (io.File f in entities) {
+      final String basename = pathlib.basename(f.path);
+      if (basename.contains('_test.dart')) {
+        // First remove this from expectedSet if not there add to the foundSet.
+        if (!expectedDriverFileNames.remove(basename)) {
+          foundDriverFileNames.add(basename);
+        }
+      } else if (basename.contains('.dart')) {
+        // Only run on dart files.
+        final String e2efileName = pathlib.basenameWithoutExtension(f.path);
+        final String expectedDriverName = '${e2efileName}_test.dart';
+        numberOfTests++;
+        // First remove this from foundSet if not there add to the expectedSet.
+        if (!foundDriverFileNames.remove(expectedDriverName)) {
+          expectedDriverFileNames.add(expectedDriverName);
+        }
+      }
+    }
+
+    if (numberOfTests == 0) {
+      throw StateError(
+          'WARNING: No tests to run in this directory ${testDirectory.path}');
+    }
+
+    // TODO(nurhan): In order to reduce the work required from team members,
+    // remove the need for driver file, by using the same template file.
+    // Some driver files are missing.
+    if (expectedDriverFileNames.length > 0) {
+      for (String expectedDriverName in expectedDriverFileNames) {
+        print('ERROR: Test driver file named has ${expectedDriverName} '
+            'not found under directory ${testDirectory.path}. Stopping the '
+            'integration tests. Please add ${expectedDriverName}. Check to '
+            'README file on more details on how to setup integration tests.');
+      }
+      throw StateError('Error in test files. Check the logs for '
+          'further instructions');
+    }
+  }
+}

engine/src/flutter/lib/web_ui/dev/test_runner.dart

@@ -15,11 +15,24 @@ import 'package:test_api/src/backend/runtime.dart'; // ignore: implementation_im
 import 'package:test_core/src/executable.dart'
     as test; // ignore: implementation_imports
 
+import 'integration_tests_manager.dart';
 import 'supported_browsers.dart';
 import 'test_platform.dart';
 import 'environment.dart';
 import 'utils.dart';
 
+/// The type of tests requested by the tool user.
+enum TestTypesRequested {
+  /// For running the unit tests only.
+  unit,
+
+  /// For running the integration tests only.
+  integration,
+
+  /// For running both unit and integration tests.
+  all,
+}
+
 class TestCommand extends Command<bool> {
   TestCommand() {
     argParser
@@ -29,6 +42,19 @@ class TestCommand extends Command<bool> {
             'opportunity to add breakpoints or inspect loaded code before '
             'running the code.',
       )
+      ..addFlag(
+        'unit-tests-only',
+        defaultsTo: false,
+        help: 'felt test command runs the unit tests and the integration tests '
+            'at the same time. If this flag is set, only run the unit tests.',
+      )
+      ..addFlag(
+        'integration-tests-only',
+        defaultsTo: false,
+        help: 'felt test command runs the unit tests and the integration tests '
+            'at the same time. If this flag is set, only run the integration '
+            'tests.',
+      )
       ..addFlag(
         'update-screenshot-goldens',
         defaultsTo: false,
@@ -54,11 +80,62 @@ class TestCommand extends Command<bool> {
   @override
   final String description = 'Run tests.';
 
+  TestTypesRequested testTypesRequested = null;
+
+  /// Check the flags to see what type of tests are requested.
+  TestTypesRequested findTestType() {
+    if (argResults['unit-tests-only'] && argResults['integration-tests-only']) {
+      throw ArgumentError('Conflicting arguments: unit-tests-only and '
+          'integration-tests-only are both set');
+    } else if (argResults['unit-tests-only']) {
+      print('Running the unit tests only');
+      return TestTypesRequested.unit;
+    } else if (argResults['integration-tests-only']) {
+      if (!isChrome) {
+        throw UnimplementedError(
+            'Integration tests are only available on Chrome Desktop for now');
+      }
+      return TestTypesRequested.integration;
+    } else {
+      return TestTypesRequested.all;
+    }
+  }
+
   @override
   Future<bool> run() async {
     SupportedBrowsers.instance
       ..argParsers.forEach((t) => t.parseOptions(argResults));
 
+    // Check the flags to see what type of integration tests are requested.
+    testTypesRequested = findTestType();
+
+    switch (testTypesRequested) {
+      case TestTypesRequested.unit:
+        return runUnitTests();
+      case TestTypesRequested.integration:
+        return runIntegrationTests();
+      case TestTypesRequested.all:
+        bool integrationTestResult = await runIntegrationTests();
+        bool unitTestResult = await runUnitTests();
+        if (integrationTestResult != unitTestResult) {
+          print('Tests run. Integration tests passed: $integrationTestResult '
+              'unit tests passed: $unitTestResult');
+        }
+        return integrationTestResult && unitTestResult;
+    }
+    return false;
+  }
+
+  Future<bool> runIntegrationTests() async {
+    // TODO(nurhan): https://github.com/flutter/flutter/issues/52983
+    if (io.Platform.environment['LUCI_CONTEXT'] != null || isCirrus) {
+      return true;
+    }
+
+    return IntegrationTestsManager(browser).runTests();
+  }
+
+  Future<bool> runUnitTests() async {
     _copyTestFontsIntoWebUi();
     await _buildHostPage();
     if (io.Platform.isWindows) {
@@ -252,18 +329,18 @@ class TestCommand extends Command<bool> {
 
   Future<void> _buildTests({List<FilePath> targets}) async {
     List<String> arguments = <String>[
-        'run',
-        'build_runner',
-        'build',
-        'test',
-        '-o',
-        'build',
-        if (targets != null)
-          for (FilePath path in targets) ...[
-            '--build-filter=${path.relativeToWebUi}.js',
-            '--build-filter=${path.relativeToWebUi}.browser_test.dart.js',
-          ],
-      ];
+      'run',
+      'build_runner',
+      'build',
+      'test',
+      '-o',
+      'build',
+      if (targets != null)
+        for (FilePath path in targets) ...[
+          '--build-filter=${path.relativeToWebUi}.js',
+          '--build-filter=${path.relativeToWebUi}.browser_test.dart.js',
+        ],
+    ];
     final int exitCode = await runProcess(
       environment.pubExecutable,
       arguments,

engine/src/flutter/lib/web_ui/dev/utils.dart

@@ -9,6 +9,7 @@ import 'dart:io' as io;
 import 'package:meta/meta.dart';
 import 'package:path/path.dart' as path;
 
+import 'common.dart';
 import 'environment.dart';
 
 class FilePath {
@@ -62,6 +63,25 @@ Future<int> runProcess(
   return exitCode;
 }
 
+/// Runs [executable]. Do not follow the exit code or the output.
+void startProcess(
+  String executable,
+  List<String> arguments, {
+  String workingDirectory,
+  bool mustSucceed: false,
+}) async {
+  final io.Process process = await io.Process.start(
+    executable,
+    arguments,
+    workingDirectory: workingDirectory,
+    // Running the process in a system shell for Windows. Otherwise
+    // the process is not able to get Dart from path.
+    runInShell: io.Platform.isWindows,
+    mode: io.ProcessStartMode.inheritStdio,
+  );
+  processesToCleanUp.add(process);
+}
+
 /// Runs [executable] and returns its standard output as a string.
 ///
 /// If the process fails, throws a [ProcessException].

engine/src/flutter/lib/web_ui/pubspec.yaml

@@ -21,3 +21,8 @@ dev_dependencies:
   watcher: 0.9.7+12
   web_engine_tester:
     path: ../../web_sdk/web_engine_tester
+  web_driver_installer:
+    git:
+      url: git://github.com/flutter/web_installers.git
+      path: packages/web_drivers/
+      ref: dae38d8839cc39f997fb4229f1382680b8758b4f