[web] Run engine tests on Safari locally by launching safari installed on MacOS (#14555)

* Launch safari browser

* Adding safari tests to supported browsers

* changing the directrory for redirect file. This works without opening a permision pop-up. Note: there is no headless mode in safari

* addressing reviewer comments

lib/web_ui/dart_test_safari.yaml

@@ -0,0 +1,7 @@
+# For more information on test and runner configurations:
+#
+# * https://github.com/dart-lang/test/blob/master/pkgs/test/doc/configuration.md#platforms
+
+platforms:
+  - safari
+  - vm

lib/web_ui/dev/common.dart

@@ -48,6 +48,7 @@ abstract class PlatformBinding {
   String getChromeExecutablePath(io.Directory versionDir);
   String getFirefoxExecutablePath(io.Directory versionDir);
   String getFirefoxLatestVersionUrl();
+  String getSafariSystemExecutablePath();
 }
 
 const String _kBaseDownloadUrl =
@@ -79,6 +80,10 @@ class _LinuxBinding implements PlatformBinding {
   @override
   String getFirefoxLatestVersionUrl() =>
       'https://download.mozilla.org/?product=firefox-latest&os=linux64&lang=en-US';
+
+  @override
+  String getSafariSystemExecutablePath() =>
+      throw UnsupportedError('Safari is not supported on Linux');
 }
 
 class _MacBinding implements PlatformBinding {
@@ -112,6 +117,10 @@ class _MacBinding implements PlatformBinding {
   @override
   String getFirefoxLatestVersionUrl() =>
       'https://download.mozilla.org/?product=firefox-latest&os=osx&lang=en-US';
+
+  @override
+  String getSafariSystemExecutablePath() =>
+      '/Applications/Safari.app/Contents/MacOS/Safari';
 }
 
 class BrowserInstallation {

lib/web_ui/dev/firefox_installer.dart

@@ -15,7 +15,7 @@ import 'environment.dart';
 class FirefoxArgParser extends BrowserArgParser {
   static final FirefoxArgParser _singletonInstance = FirefoxArgParser._();
 
-  /// The [ChromeArgParser] singleton.
+  /// The [FirefoxArgParser] singleton.
   static FirefoxArgParser get instance => _singletonInstance;
 
   String _version;

lib/web_ui/dev/safari.dart

@@ -0,0 +1,67 @@
+// 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:async';
+import 'dart:convert';
+import 'dart:io';
+
+import 'environment.dart';
+
+import 'package:path/path.dart' as path;
+import 'package:pedantic/pedantic.dart';
+
+import 'package:test_core/src/util/io.dart'; // ignore: implementation_imports
+
+import 'browser.dart';
+import 'safari_installation.dart';
+import 'common.dart';
+
+/// A class for running an instance of Safari.
+///
+/// Most of the communication with the browser is expected to happen via HTTP,
+/// so this exposes a bare-bones API. The browser starts as soon as the class is
+/// constructed, and is killed when [close] is called.
+///
+/// Any errors starting or running the process are reported through [onExit].
+class Safari extends Browser {
+  @override
+  final name = 'Safari';
+
+  static String version;
+
+  /// Starts a new instance of Safari open to the given [url], which may be a
+  /// [Uri] or a [String].
+  factory Safari(Uri url, {bool debug = false}) {
+    version = SafariArgParser.instance.version;
+
+    assert(version != null);
+    return Safari._(() async {
+      // TODO(nurhan): Configure info log for LUCI.
+      final BrowserInstallation installation = await getOrInstallSafari(
+        version,
+        infoLog: DevNull(),
+      );
+
+      // Safari will only open files (not general URLs) via the command-line
+      // API, so we create a dummy file to redirect it to the page we actually
+      // want it to load.
+      final Directory redirectDir = Directory(
+        path.join(environment.webUiDartToolDir.path),
+      );
+      final redirect = path.join(redirectDir.path, 'redirect.html');
+      File(redirect).writeAsStringSync(
+          '<script>location = ' + jsonEncode(url.toString()) + '</script>');
+
+      var process =
+          await Process.start(installation.executable, [redirect] /* args */);
+
+      unawaited(process.exitCode
+          .then((_) => File(redirect).deleteSync(recursive: true)));
+
+      return process;
+    });
+  }
+
+  Safari._(Future<Process> startBrowser()) : super(startBrowser);
+}

lib/web_ui/dev/safari_installation.dart

@@ -0,0 +1,79 @@
+// 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:async';
+import 'dart:io' as io;
+
+import 'package:args/args.dart';
+
+import 'common.dart';
+
+class SafariArgParser extends BrowserArgParser {
+  static final SafariArgParser _singletonInstance = SafariArgParser._();
+
+  /// The [SafariArgParser] singleton.
+  static SafariArgParser get instance => _singletonInstance;
+
+  String _version;
+
+  SafariArgParser._();
+
+  @override
+  void populateOptions(ArgParser argParser) {
+    argParser
+      ..addOption(
+        'safari-version',
+        defaultsTo: 'system',
+        help: 'The Safari version to use while running tests. The Safari '
+            'browser installed on the system is used as the only option now.'
+            'Soon we will add support for using different versions using the '
+            'tech previews.',
+      );
+  }
+
+  @override
+  void parseOptions(ArgResults argResults) {
+    _version = argResults['safari-version'];
+    assert(_version == 'system');
+  }
+
+  @override
+  String get version => _version;
+}
+
+/// Returns the installation of Safari.
+///
+/// Currently uses the Safari version installed on the operating system.
+///
+/// Latest Safari version for Catalina, Mojave, High Siera is 13.
+///
+/// Latest Safari version for Sierra is 12.
+// TODO(nurhan): user latest version to download and install the latest
+// technology preview.
+Future<BrowserInstallation> getOrInstallSafari(
+  String requestedVersion, {
+  StringSink infoLog,
+}) async {
+
+  // These tests are aimed to run only on MacOs machines local or on LUCI.
+  if (!io.Platform.isMacOS) {
+    throw UnimplementedError('Safari on ${io.Platform.operatingSystem} is'
+        ' not supported. Safari is only supported on MacOS.');
+  }
+
+  infoLog ??= io.stdout;
+
+  if (requestedVersion == 'system') {
+    // Since Safari is included in MacOS, always assume there will be one on the
+    // system.
+    infoLog.writeln('Using the system version that is already installed.');
+    return BrowserInstallation(
+      version: 'system',
+      executable: PlatformBinding.instance.getSafariSystemExecutablePath(),
+    );
+  } else {
+    infoLog.writeln('Unsupported version $requestedVersion.');
+    throw UnimplementedError();
+  }
+}

lib/web_ui/dev/supported_browsers.dart

@@ -10,7 +10,9 @@ import 'chrome_installer.dart';
 import 'common.dart';
 import 'environment.dart';
 import 'firefox.dart';
-import 'firefox_installer.dart'; // ignore: implementation_imports
+import 'firefox_installer.dart';
+import 'safari.dart';
+import 'safari_installation.dart';
 
 /// Utilities for browsers, that tests are supported.
 ///
@@ -22,18 +24,20 @@ import 'firefox_installer.dart'; // ignore: implementation_imports
 /// One should also implement [BrowserArgParser] and add it to the [argParsers].
 class SupportedBrowsers {
   final List<BrowserArgParser> argParsers =
-      List.of([ChromeArgParser.instance, FirefoxArgParser.instance]);
+      List.of([ChromeArgParser.instance, FirefoxArgParser.instance, SafariArgParser.instance]);
 
-  final List<String> supportedBrowserNames = ['chrome', 'firefox'];
+  final List<String> supportedBrowserNames = ['chrome', 'firefox', 'safari'];
 
   final Map<String, Runtime> supportedBrowsersToRuntimes = {
     'chrome': Runtime.chrome,
-    'firefox': Runtime.firefox
+    'firefox': Runtime.firefox,
+    'safari': Runtime.safari,
   };
 
   final Map<String, String> browserToConfiguration = {
     'chrome': '--configuration=${environment.webUiRootDir.path}/dart_test_chrome.yaml',
     'firefox': '--configuration=${environment.webUiRootDir.path}/dart_test_firefox.yaml',
+    'safari': '--configuration=${environment.webUiRootDir.path}/dart_test_safari.yaml',
   };
 
   static final SupportedBrowsers _singletonInstance = SupportedBrowsers._();
@@ -48,6 +52,8 @@ class SupportedBrowsers {
       return Chrome(url, debug: debug);
     } else if (runtime == Runtime.firefox) {
       return Firefox(url, debug: debug);
+    } else if (runtime == Runtime.safari) {
+      return Safari(url, debug: debug);
     } else {
       throw new UnsupportedError('The browser type not supported in tests');
     }