Add browser controller and allow it to be used under a flag.

tools/testing/dart/browser_controller.dart

Index: tools/testing/dart/browser_controller.dart
===================================================================
--- tools/testing/dart/browser_controller.dart	(revision 0)
+++ tools/testing/dart/browser_controller.dart	(revision 0)
@@ -0,0 +1,687 @@
+// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+library browser;
+
+import "dart:async";
+import "dart:core";
+import "dart:io";
+
+
+/** Class describing the interface for communicating with browsers. */
+class Browser {
+  // Browsers actually takes a while to cleanup after itself when closing
+  // Give it sufficient time to do that.
+  static final Duration killRepeatInternal = const Duration(seconds: 10);
+  static final int killRetries = 5;
+  StringBuffer _stdout = new StringBuffer();
+  StringBuffer _stderr = new StringBuffer();
+  StringBuffer _usageLog = new StringBuffer();
+  // This function is called when the process is closed.
+  // This is extracted to an external function so that we can do additional
+  // functionality when the process closes (cleanup and call onExit)
+  Function _processClosed;
+  // This is called after the process is closed, after _processClosed has
+  // been called, but before onExit. Subclasses can use this to cleanup
+  // any browser specific resources (temp directories, profiles, etc)
+  Function _cleanup;

[kustermann, 2013/05/14 09:05:24]

We have a ton of callback in this code. In this case for example you could make
it a completer (and rename this to 'browserDidExitFuture'). Everyone who is
interested in it could register for the event.

+
+  /** The version of the browser - normally set when starting a browser */
+  String version = "";
+  /**
+   * The underlying process - don't mess directly with this if you don't
+   * know what you are doing (this is an interactive process that needs
+   * special threatment to not leak).
+   */
+  Process process;
+
+  /**
+   * Id of the browser
+   */
+  String id;
+
+  /** Callback that will be executed when the browser has closed */
+  Function onClose;
+
+  /** Print everything (stdout, stderr, usageLog) whenever we add to it */
+  bool debugPrint = false;
+
+  void _logEvent(String event) {
+    String toLog = "$this ($id) - ${new DateTime.now()}: $event \n";
+    if (debugPrint) print("usageLog: $toLog");
+    _usageLog.write(toLog);

[kustermann, 2013/05/14 09:05:24]

a) Is the 'debugPrint' still used?
b) You don't write \n' here and the call sites don't do it either?

+  }
+
+  void _addStdout(String output) {
+    if (debugPrint) print("stdout: $output");
+    _stdout.write(output);
+  }
+
+  void _addStderr(String output) {
+    if (debugPrint) print("stderr: $output");
+    _stderr.write(output);
+  }
+
+  // Kill the underlying process using the supplied kill function
+  // If there is a alternativeKillFunction we will use that after trying
+  // the default killFunction.
+  Future _killIt(killFunction, retries, [alternativeKillFunction = null]) {
+    Completer<bool> completer = new Completer<bool>();
+
+    // To capture non successfull attempts we set up a timer that will
+    // trigger a retry (using the alternativeKillFunction if supplied).
+    Timer timer =  new Timer(killRepeatInternal, () {
+      // Remove the handler, we will set this again in the call to killIt
+      // below
+      if (retries <= 0) {
+        _logEvent("Could not kill the process, not trying anymore");
+        // TODO(ricow): Should we crash the test script here and
+        // write out all our log. This is basically not a situation
+        // that we want to ignore. We could potentially have a handler we
+        // can call if this happens, which will shutdown the main process
+        // with info that people should contact [ricow,kustermann,?]
+        completer.complete(false);

[kustermann, 2013/05/14 09:05:24]

What about calling utils.py:die("....")?

+      }
+      _logEvent("Could not kill the process, retrying");
+      var nextKillFunction = killFunction;
+      if (alternativeKillFunction != null) {
+        nextKillFunction = alternativeKillFunction;
+      }
+      _killIt(nextKillFunction, retries - 1).then((success) {
+        completer.complete(success);
+      });
+    });
+
+    // Make sure we intercept onExit calls and eliminate the timer.
+    _processClosed = () {
+      timer.cancel();
+      _logEvent("Proccess exited, cancel timer in kill loop");
+      _processClosed = null;
+      completer.complete(true);

[kustermann, 2013/05/14 09:05:24]

You could set 'process = null' here.

+    };
+
+
+    _logEvent("calling kill function");
+    if (killFunction()) {
+      // We successfully sent the signal.
+      _logEvent("killing signal sent");
+    } else {
+      _logEvent("The process is already dead, kill signal could not be send");
+      completer.complete(true);
+    }
+    return completer.future;
+  }
+
+
+  /** Close the browser */
+  Future<bool> close() {
+    _logEvent("Close called on browser");
+    if (process == null) {
+      _logEvent("No process open, nothing to kill.");
+      return new Future.immediate(true);
+    }
+    var killFunction = process.kill;
+    // We use a SIGKILL signal if we don't kill the process in the first go.
+    var alternativeKillFunction =
+        () { return process.kill(ProcessSignal.SIGKILL);};
+    return _killIt(killFunction, killRetries, alternativeKillFunction);
+  }
+
+  /**
+   * Start the browser using the supplied argument.
+   * This sets up the error handling and usage logging.
+   */
+  Future<bool> startBrowser(String command, List<String> arguments) {
+    return Process.start(command, arguments).then((p) {

[kustermann, 2013/05/14 09:05:24]

I have no strong opinion about this, but you told me we don't abbreviate? (p, e
...)

+      process = p;
+      p.stdout.transform(new StringDecoder()).listen((data) {
+        _addStdout(data);
+      }, onError: (e) {
+        // This should _never_ happen, but we really want this in the log
+        // if it actually does due to dart:io or vm bug.
+        _usageLog.add("An error occured in the process stdout handling: $e");
+      });
+
+      p.stderr.transform(new StringDecoder()).listen((data) {
+        _addStderr(data);
+      }, onError: (e) {
+        // This should _never_ happen, but we really want this in the log
+        // if it actually does due to dart:io or vm bug.
+        _usageLog.add("An error occured in the process stderr handling: $e");
+      });
+
+      process.exitCode.then((exitCode) {
+        _logEvent("Browser closed with exitcode $exitCode");
+        if (_processClosed != null) _processClosed();
+        if (_cleanup != null) _cleanup();
+        if (onClose != null) onClose(exitCode);
+        });

[kustermann, 2013/05/14 09:05:24]

Indentation.

+      return true;
+    }).catchError((e) {
+      _logEvent("Running $binary $arguments failed with $e");
+      return false;
+    });
+  }
+
+  /**
+   * Get any stdout that the browser wrote during execution.
+   */
+  String get stdout => _stdout.toString();
+  String get stderr => _stderr.toString();
+  String get usageLog => _usageLog.toString();

[kustermann, 2013/05/14 09:05:24]

Where are these three variables used?

+
+  String toString();
+  /** Starts the browser loading the given url */
+  Future<bool> start(String url);
+}
+
+
+class Chrome extends Browser {
+  /**
+   * The binary used to run chrome - changing this can be nececcary for
+   * testing or using non standard chrome installation.
+   */
+  const String binary = "google-chrome";
+
+  Future<bool> start(String url) {
+    _logEvent("Starting chrome browser on: $url");
+    // Get the version and log that.
+    return Process.run(binary, ["--version"]).then((var versionResult) {
+      if (versionResult.exitCode != 0) {
+        _logEvent("Failed to chrome get version");
+        _logEvent("Make sure $binary is a valid program for running chrome");
+        return new Future.immediate(false);
+      }
+      version = versionResult.stdout;
+      _logEvent("Got version: $version");
+
+      return new Directory('').createTemp().then((userDir) {
+        _cleanup = () { userDir.delete(recursive: true); };
+        var args = ["--user-data-dir=${userDir.path}", url,
+                    "--disable-extensions", "--disable-popup-blocking",
+                    "--bwsi"];
+        return startBrowser(binary, args);
+
+      });
+    }).catchError((e) {
+      _logEvent("Running $binary --version failed with $e");
+      return false;
+    });
+  }
+
+  String toString() => "Chrome";
+}
+
+class Firefox extends Browser {
+  /**
+   * The binary used to run firefox - changing this can be nececcary for
+   * testing or using non standard firefox installation.
+   */
+  const String binary = "firefox";
+
+  const String enablePopUp =
+      "user_pref(\"dom.disable_open_during_load\", false);";
+
+  Future _createPreferenceFile(var path) {
+    var file = new File("${path.toString()}/user.js");
+    var randomFile = file.openSync(FileMode.WRITE);
+    randomFile.writeStringSync(enablePopUp);
+    randomFile.close();
+  }
+
+
+  Future<bool> start(String url) {
+    _logEvent("Starting firefox browser on: $url");
+    // Get the version and log that.
+    return Process.run(binary, ["--version"]).then((var versionResult) {
+      if (versionResult.exitCode != 0) {
+        _logEvent("Failed to firefox get version");
+        _logEvent("Make sure $binary is a valid program for running firefox");
+        return new Future.immediate(false);
+      }
+      version = versionResult.stdout;
+      _logEvent("Got version: $version");
+
+      return new Directory('').createTemp().then((userDir) {
+        _createPreferenceFile(userDir.path);
+        _cleanup = () { userDir.delete(recursive: true); };
+        var args = ["-profile", "${userDir.path}",
+                    "-no-remote", "-new-instance", url];
+        return startBrowser(binary, args);
+
+      });
+    }).catchError((e) {
+      _logEvent("Running $binary --version failed with $e");
+      return false;
+    });
+  }
+
+  String toString() => "Firefox";
+}
+
+
+/**
+ * Describes the current state of a browser used for testing.
+ */
+class BrowserTestingStatus {
+// TODO(ricow): Add prefetching to the browsers. We spend a lot of time waiting
+// for the next test. Handling timeouts is the hard part of this!
+
+
+  Browser browser;
+  BrowserTest currentlyRunning;

[kustermann, 2013/05/14 09:05:24]

'currentlyRunning' feels like it's a boolean or so. You could rename it to
'currentTest'.

+  // This is currently not used for anything except for error reporting.
+  // Given the usefulness of this in debugging issues this should not be
+  // removed even when we have really stable system.
+  BrowserTest last;

[kustermann, 2013/05/14 09:05:24]

last -> lastTest

+  bool timeout = false;
+  BrowserTestingStatus(Browser this.browser);
+}
+
+
+/**
+ * Describes a single test to be run int the browser.
+ */
+class BrowserTest {
+  // TODO(ricow): Add timeout callback instead of the string passing hack.
+  Function doneCallback;

[kustermann, 2013/05/14 09:05:24]

Again, we could make it a completer and let the test_runner just do
"runTest().then((result) {})".

+  String url;
+  int timeout;
+  // We store this here for easy access when tests time out (instead of
+  // capturing this in a closure)
+  Timer timeoutTimer;
+
+  // Used for debugging, this is simply a unique identifier assigned to each
+  // test.
+  int id;
+  static int _idCounter = 0;
+
+  BrowserTest(this.url, this.doneCallback, this.timeout) {
+    id = _idCounter++;
+  }
+}
+
+
+/**
+ * Encapsulates all the functionality for running tests in browsers.
+ * The interface is rather simple. After starting the runner tests
+ * are simply added to the queue and a the supplied callbacks are called
+ * whenever a test completes.
+ */
+class BrowserTestRunner {
+  int maxNumBrowsers;
+  String browserName;
+
+  bool underTermination = false;
+
+  List<BrowserTest> testQueue = new List<BrowserTest>();
+  Map<String, BrowserTestingStatus> browserStatus =
+      new Map<String, BrowserTestingStatus>();

[kustermann, 2013/05/14 09:05:24]

The type of the variable should be inferred -- no need to note it twice?

+  // This cache is used to guarantee that we never see double reporting.
+  // If we do we need to provide developers with this information.
+  // We don't add urls to the cache until we have run it.
+  Map<int, String> testCache = new Map<int, String>();
+  List<int> doubleReportingTests = new List<int>();
+
+  BrowserTestingServer testingServer;
+
+  BrowserTestRunner(String this.browserName, int this.maxNumBrowsers);
+
+  Future<bool> start() {
+    testingServer = new BrowserTestingServer();
+    return testingServer.start().then((_) {
+      testingServer.testDoneCallBack = handleResults;
+      testingServer.nextTestCallBack = getNextTest;
+      var futures = [];
+      for (int i = 0; i < maxNumBrowsers; i++) {
+        var browser = getInstance();
+        var id = "BROWSER$i";
+        // We store this in case we need to kill the browser.
+        browser.id = id;
+        var future =
+            browser.start(testingServer.getDriverUrl(id)).then((success) {
+              if (success) {
+                browserStatus[id] = new BrowserTestingStatus(browser);
+              }
+              return success;
+            });
+        futures.add(future);
+      }
+      return Future.wait(futures).then((values) {
+        return !values.contains(false);
+      });
+    });
+  }
+
+  var timedOut = [];
+
+  void handleResults(String browserId, String output, int testId) {
+    var status = browserStatus[browserId];
+    if (testCache.containsKey(testId)) {
+      doubleReportingTests.add(testId);
+      return;
+    }
+
+    if (status.timeout) {
+      // We don't do anything, this browser is currently being killed and
+      // replaced.
+    } else if (status.currentlyRunning != null) {
+      status.currentlyRunning.timeoutTimer.cancel();
+      if (status.currentlyRunning.id != testId) {
+        print("Expected test id ${status.currentlyRunning.id} for"
+              "${status.currentlyRunning.url}");
+        print("Got test id ${testId}");
+        print("Last test id was ${status.last.id} for "
+              "${status.currentlyRunning.url}");
+        throw("This should never happen, wrong test id");
+      }
+      testCache[testId] = status.currentlyRunning.url;
+      status.currentlyRunning.doneCallback(output);
+      status.last = status.currentlyRunning;
+      status.currentlyRunning = null;
+    } else {
+      print("\nThis is bad, should never happen, handleResult no test");
+      print("URL: ${status.last.url}");
+      print(output);
+      terminate().then((_) {
+        exit(1);
+      });
+    }
+  }
+
+  void handleTimeout(BrowserTestingStatus status) {
+    // We simply kill the browser and starts up a new one!
+    // We could be smarter here, but it does not seems like it is worth it.
+    status.timeout = true;
+    timedOut.add(status.currentlyRunning.url);
+    // Start the new browser first
+    var browser = getInstance();

[kustermann, 2013/05/14 09:05:24]

The comment is outdated now + nove the 'getInstance()' inside
'status.browser.close().then((_) { ....}'

+    var id = status.browser.id;
+    status.browser.close().then((closed) {
+      if (!closed) {
+        // Very bad, we could not kill the browser.
+        print("could not kill browser $id");
+        return;
+      }
+      browser.start(testingServer.getDriverUrl(id)).then((success) {
+        // We may have started terminating in the mean time.
+        if (underTermination) {
+          browser.close().then((success) {

[kustermann, 2013/05/14 09:05:24]

If we're 'underTermination' then the 'browser.close()' is already called in the
'terminate()' function.

+            // We should never hit this, print it out.
+            if (!success) {
+              print("Could not kill browser ($id) started due to timeout");
+            }
+          });
+        return;

[kustermann, 2013/05/14 09:05:24]

indentation

+        }
+        if (success) {
+          browser.id = id;
+          status.browser = browser;
+          status.timeout = false;
+        } else {
+          // TODO(ricow): Handle this better.
+          print("This is bad, should never happen, could not start browser");
+          exit(1);
+        }
+      });
+    });
+
+    status.currentlyRunning.doneCallback("TIMEOUT");
+    status.currentlyRunning = null;
+  }
+
+  BrowserTest getNextTest(String browserId) {
+    if (testQueue.isEmpty) return null;
+    var status = browserStatus[browserId];
+    if (status == null) return null;
+    // We are currently terminating this browser, don't start a new test.
+    if (status.timeout) return null;
+    BrowserTest test = testQueue.removeLast();
+    if (status.currentlyRunning == null) {
+      status.currentlyRunning = test;
+    } else {
+      // TODO(ricow): Handle this better.
+      print("This is bad, should never happen, getNextTest all full");
+      print("Old test was: ${status.currentlyRunning.url}");
+      print("Timed out tests:");
+      for (var v in timedOut) {
+        print("  $v");
+      }
+      exit(1);

[kustermann, 2013/05/14 09:05:24]

utils.py:die() ?

+    }
+    Timer timer = new Timer(new Duration(seconds: test.timeout),
+                            () { handleTimeout(status); });
+    status.currentlyRunning.timeoutTimer = timer;
+    return test;
+  }
+
+  void queueTest(BrowserTest test) {
+    testQueue.add(test);
+  }
+
+  void printDoubleReportingTests() {
+    if (doubleReportingTests.length == 0) return;
+    // Currently we just report this here, we could have a callback to the
+    // encapsulating environment.
+    print("");
+    print("Double reporting tests");
+    for (var id in doubleReportingTests) {
+      print("  ${testCache[id]}");
+    }

[kustermann, 2013/05/14 09:05:24]

Add a TODO to 'die()' in the future if we get double reportings.

+  }
+
+  Future<bool> terminate() {
+    var futures = [];
+    underTermination = true;
+    testingServer.underTermination = true;
+    for (BrowserTestingStatus status in browserStatus.values) {
+      futures.add(status.browser.close());
+    }
+    return Future.wait(futures).then((values) {
+      testingServer.httpServer.close();
+      printDoubleReportingTests();
+      return !values.contains(false);
+    });
+  }
+
+  Browser getInstance() {
+    if (browserName == "chrome") {
+      return new Chrome();
+    } else if (browserName == "firefox") {
+      return new Firefox();
+    }
+    throw "Non supported browser for browser controller";
+  }
+}
+
+class BrowserTestingServer {
+  const String server = "127.0.0.1";
+
+  /// Interface of the testing server:
+  ///
+  /// /driver: This will get the driver page to fetch and run tests
+  /// /nextTestPath: This will get the next available test to run, returned
+  ///                as a url and an id. If there are currently no available
+  ///                tests the waitSignal is send back. If we are in the
+  ///                process of terminating the terminateSignal is send back
+  ///                and the browser will stop requesting new tasks.
+  /// /reportPath: Used for shipping back the result of running a test.

[kustermann, 2013/05/14 09:05:24]

This is not the interface. Please document exactly how things work (it's even
hard for me to figure it out). Something like
GET /driver/BROWSER_ID -- ...
GET /next_test/BROWSER_ID -- returns "WAIT" "TERMINATE" or ... "...#id'
POST /report/BROWSER_ID?id=NUM -- ...

+
+
+  const String driverPath = "/driver";
+  const String nextTestPath = "/next_test";
+  const String reportPath = "/report";
+  const String waitSignal = "WAIT";
+  const String terminateSignal = "TERMINATE";
+
+  var testCount = 0;
+  var httpServer;
+  bool underTermination = false;
+
+  Function testDoneCallBack;
+  Function nextTestCallBack;
+
+  Future start() {
+    return HttpServer.bind(server, 0).then((createdServer) {
+      httpServer = createdServer;
+      void handler(HttpRequest request) {
+        if (request.uri.path.startsWith(reportPath)) {
+          var browserId = request.uri.path.substring(reportPath.length + 1);
+          var testId = int.parse(request.queryParameters["id"].split("=")[1]);
+
+          handleReport(request, browserId, testId);
+          // handleReport will asynchroniously fetch the data and will handle
+          // the closing of the streams.
+          return;
+        }
+        var textResponse = "";
+        if (request.uri.path.startsWith(driverPath)) {
+          var browserId = request.uri.path.substring(driverPath.length + 1);
+          textResponse = getDriverPage(browserId);
+        } else if (request.uri.path.startsWith(nextTestPath)) {
+          var browserId = request.uri.path.substring(nextTestPath.length + 1);
+          textResponse = getNextTest(browserId);
+        } else {
+          // We silently ignore other requests.
+        }
+        request.response.write(textResponse);
+        request.listen((_) {}, onDone: request.response.close);
+        request.response.done.catchError((error) {
+        if (!underTermination) {
+          print("URI ${request.uri}");
+          print("Textresponse $textResponse");
+          throw("Error returning content to browser: $error");
+        }
+      });
+      }
+      void errorHandler(e) {
+        if (!underTermination) print("Error occured in httpserver: $e");
+      };
+      httpServer.listen(handler, onError: errorHandler);
+      return true;
+    });
+  }
+
+  void handleReport(HttpRequest request, String browserId, var testId) {
+    StringBuffer buffer = new StringBuffer();
+    request.transform(new StringDecoder()).listen((data) {
+      buffer.write(data);
+      }, onDone: () {
+        String back = buffer.toString();
+        request.response.close();
+        testDoneCallBack(browserId, back, testId);
+      }, onError: (error) { print(error); });
+  }
+
+  String getNextTest(String browserId) {
+    var nextTest = nextTestCallBack(browserId);
+    if (underTermination) {
+      // Browsers will be killed shortly, send them a terminate signal so
+      // that they stop pulling.
+      return terminateSignal;
+    } else if (nextTest == null) {
+      // We don't currently have any tests ready for consumption, wait.
+      return waitSignal;
+    } else {
+      return "${nextTest.url}#id=${nextTest.id}";
+    }
+  }
+
+  String getDriverUrl(String browserId) {
+    if (httpServer == null) {
+      print("Bad browser testing server, you are not started yet. Can't "
+            "produce driver url");
+      exit(1);
+      // This should never happen - exit immediately;
+    }
+    return "http://$server:${httpServer.port}/driver/$browserId";
+  }
+
+
+  String getDriverPage(String browserId) {
+    String driverContent = """
+<!DOCTYPE html><html>
+<head>
+  <title>Driving page</title>
+  <script type='text/javascript'>
+    var numberOfTests = 0;
+    var currentId;
+    var testing_window;
+
+    function newTaskHandler() {
+      if (this.readyState == this.DONE) {
+        if (this.status == 200) {
+          if (this.responseText == '$waitSignal') {
+            setTimeout(getNextTask, 500);
+          } else if (this.responseText == 'TERMINATE') {

[kustermann, 2013/05/14 09:05:24]

Use the constant above (i.e. " == '$terminateSignal').

+            // Don't do anything, we will be killed shortly.
+          } else {
+            // TODO(ricow): Do something more clever here.
+            if (nextTask != undefined) alert('This is really bad');
+            // The task is send to us as:
+            // URL#ID
+            var split = this.responseText.split('#');
+            var nextTask = split[0];
+            id = split[1];
+            run(nextTask);
+          }
+        } else {
+          // We are basically in trouble - do something clever.
+        }
+      }
+    }
+
+    function getNextTask() {
+      var client = new XMLHttpRequest();
+      client.onreadystatechange = newTaskHandler;
+      client.open('GET', '$nextTestPath/$browserId');
+      client.send();
+    }
+
+    function run(url) {
+      numberOfTests++;
+      document.getElementById('number').innerHTML = numberOfTests;
+      if (testing_window == undefined) {
+        testing_window = window.open(url);
+      } else {
+        testing_window.location = url;
+      }
+    }
+
+    function reportMessage(msg) {
+      var client = new XMLHttpRequest();
+      function handleReady() {
+        if (this.readyState == this.DONE) {
+          getNextTask();
+        }
+      }
+      client.onreadystatechange = handleReady;
+      client.open('POST', '$reportPath/${browserId}?id=' + id);
+      client.setRequestHeader('Content-type',
+                              'application/x-www-form-urlencoded');
+      client.send(msg);
+      // TODO(ricow) add error handling to somehow report the fact that
+      // we could not send back a result.
+    }
+
+    function messageHandler(e) {
+      var msg = e.data;
+      if (typeof msg != 'string') return;
+      reportMessage(msg);
+    }
+
+    window.addEventListener('message', messageHandler, false);
+    waitForDone = false;
+
+    getNextTask();
+
+  </script>
+</head>
+  <body>
+    Dart test driver, number of tests: <div id="number"></div>
+  </body>
+</html>
+""";
+    return driverContent;
+  }
+}