Adding upstream version 124.0.1.upstream/124.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2660 insertions, 0 deletions

diff --git a/accessible/tests/mochitest/events.js b/accessible/tests/mochitest/events.js
new file mode 100644
index 0000000000..a6c216e01d
--- /dev/null
+++ b/accessible/tests/mochitest/events.js
@@ -0,0 +1,2660 @@
+/* import-globals-from common.js */
+/* import-globals-from states.js */
+/* import-globals-from text.js */
+
+// XXX Bug 1425371 - enable no-redeclare and fix the issues with the tests.
+/* eslint-disable no-redeclare */
+
+// //////////////////////////////////////////////////////////////////////////////
+// Constants
+
+const EVENT_ALERT = nsIAccessibleEvent.EVENT_ALERT;
+const EVENT_ANNOUNCEMENT = nsIAccessibleEvent.EVENT_ANNOUNCEMENT;
+const EVENT_DESCRIPTION_CHANGE = nsIAccessibleEvent.EVENT_DESCRIPTION_CHANGE;
+const EVENT_DOCUMENT_LOAD_COMPLETE =
+  nsIAccessibleEvent.EVENT_DOCUMENT_LOAD_COMPLETE;
+const EVENT_DOCUMENT_RELOAD = nsIAccessibleEvent.EVENT_DOCUMENT_RELOAD;
+const EVENT_DOCUMENT_LOAD_STOPPED =
+  nsIAccessibleEvent.EVENT_DOCUMENT_LOAD_STOPPED;
+const EVENT_HIDE = nsIAccessibleEvent.EVENT_HIDE;
+const EVENT_FOCUS = nsIAccessibleEvent.EVENT_FOCUS;
+const EVENT_NAME_CHANGE = nsIAccessibleEvent.EVENT_NAME_CHANGE;
+const EVENT_MENU_START = nsIAccessibleEvent.EVENT_MENU_START;
+const EVENT_MENU_END = nsIAccessibleEvent.EVENT_MENU_END;
+const EVENT_MENUPOPUP_START = nsIAccessibleEvent.EVENT_MENUPOPUP_START;
+const EVENT_MENUPOPUP_END = nsIAccessibleEvent.EVENT_MENUPOPUP_END;
+const EVENT_OBJECT_ATTRIBUTE_CHANGED =
+  nsIAccessibleEvent.EVENT_OBJECT_ATTRIBUTE_CHANGED;
+const EVENT_REORDER = nsIAccessibleEvent.EVENT_REORDER;
+const EVENT_SCROLLING_START = nsIAccessibleEvent.EVENT_SCROLLING_START;
+const EVENT_SELECTION = nsIAccessibleEvent.EVENT_SELECTION;
+const EVENT_SELECTION_ADD = nsIAccessibleEvent.EVENT_SELECTION_ADD;
+const EVENT_SELECTION_REMOVE = nsIAccessibleEvent.EVENT_SELECTION_REMOVE;
+const EVENT_SELECTION_WITHIN = nsIAccessibleEvent.EVENT_SELECTION_WITHIN;
+const EVENT_SHOW = nsIAccessibleEvent.EVENT_SHOW;
+const EVENT_STATE_CHANGE = nsIAccessibleEvent.EVENT_STATE_CHANGE;
+const EVENT_TEXT_ATTRIBUTE_CHANGED =
+  nsIAccessibleEvent.EVENT_TEXT_ATTRIBUTE_CHANGED;
+const EVENT_TEXT_CARET_MOVED = nsIAccessibleEvent.EVENT_TEXT_CARET_MOVED;
+const EVENT_TEXT_INSERTED = nsIAccessibleEvent.EVENT_TEXT_INSERTED;
+const EVENT_TEXT_REMOVED = nsIAccessibleEvent.EVENT_TEXT_REMOVED;
+const EVENT_TEXT_SELECTION_CHANGED =
+  nsIAccessibleEvent.EVENT_TEXT_SELECTION_CHANGED;
+const EVENT_VALUE_CHANGE = nsIAccessibleEvent.EVENT_VALUE_CHANGE;
+const EVENT_TEXT_VALUE_CHANGE = nsIAccessibleEvent.EVENT_TEXT_VALUE_CHANGE;
+const EVENT_VIRTUALCURSOR_CHANGED =
+  nsIAccessibleEvent.EVENT_VIRTUALCURSOR_CHANGED;
+
+const kNotFromUserInput = 0;
+const kFromUserInput = 1;
+
+// //////////////////////////////////////////////////////////////////////////////
+// General
+
+/**
+ * Set up this variable to dump events into DOM.
+ */
+var gA11yEventDumpID = "";
+
+/**
+ * Set up this variable to dump event processing into console.
+ */
+var gA11yEventDumpToConsole = false;
+
+/**
+ * Set up this variable to dump event processing into error console.
+ */
+var gA11yEventDumpToAppConsole = false;
+
+/**
+ * Semicolon separated set of logging features.
+ */
+var gA11yEventDumpFeature = "";
+
+/**
+ * Function to detect HTML elements when given a node.
+ */
+function isHTMLElement(aNode) {
+  return (
+    aNode.nodeType == aNode.ELEMENT_NODE &&
+    aNode.namespaceURI == "http://www.w3.org/1999/xhtml"
+  );
+}
+
+function isXULElement(aNode) {
+  return (
+    aNode.nodeType == aNode.ELEMENT_NODE &&
+    aNode.namespaceURI ==
+      "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+  );
+}
+
+/**
+ * Executes the function when requested event is handled.
+ *
+ * @param aEventType  [in] event type
+ * @param aTarget     [in] event target
+ * @param aFunc       [in] function to call when event is handled
+ * @param aContext    [in, optional] object in which context the function is
+ *                    called
+ * @param aArg1       [in, optional] argument passed into the function
+ * @param aArg2       [in, optional] argument passed into the function
+ */
+function waitForEvent(
+  aEventType,
+  aTargetOrFunc,
+  aFunc,
+  aContext,
+  aArg1,
+  aArg2
+) {
+  var handler = {
+    handleEvent: function handleEvent(aEvent) {
+      var target = aTargetOrFunc;
+      if (typeof aTargetOrFunc == "function") {
+        target = aTargetOrFunc.call();
+      }
+
+      if (target) {
+        if (target instanceof nsIAccessible && target != aEvent.accessible) {
+          return;
+        }
+
+        if (Node.isInstance(target) && target != aEvent.DOMNode) {
+          return;
+        }
+      }
+
+      unregisterA11yEventListener(aEventType, this);
+
+      window.setTimeout(function () {
+        aFunc.call(aContext, aArg1, aArg2);
+      }, 0);
+    },
+  };
+
+  registerA11yEventListener(aEventType, handler);
+}
+
+/**
+ * Generate mouse move over image map what creates image map accessible (async).
+ * See waitForImageMap() function.
+ */
+function waveOverImageMap(aImageMapID) {
+  var imageMapNode = getNode(aImageMapID);
+  synthesizeMouse(
+    imageMapNode,
+    10,
+    10,
+    { type: "mousemove" },
+    imageMapNode.ownerGlobal
+  );
+}
+
+/**
+ * Call the given function when the tree of the given image map is built.
+ */
+function waitForImageMap(aImageMapID, aTestFunc) {
+  waveOverImageMap(aImageMapID);
+
+  var imageMapAcc = getAccessible(aImageMapID);
+  if (imageMapAcc.firstChild) {
+    aTestFunc();
+    return;
+  }
+
+  waitForEvent(EVENT_REORDER, imageMapAcc, aTestFunc);
+}
+
+/**
+ * Register accessibility event listener.
+ *
+ * @param aEventType     the accessible event type (see nsIAccessibleEvent for
+ *                       available constants).
+ * @param aEventHandler  event listener object, when accessible event of the
+ *                       given type is handled then 'handleEvent' method of
+ *                       this object is invoked with nsIAccessibleEvent object
+ *                       as the first argument.
+ */
+function registerA11yEventListener(aEventType, aEventHandler) {
+  listenA11yEvents(true);
+  addA11yEventListener(aEventType, aEventHandler);
+}
+
+/**
+ * Unregister accessibility event listener. Must be called for every registered
+ * event listener (see registerA11yEventListener() function) when the listener
+ * is not needed.
+ */
+function unregisterA11yEventListener(aEventType, aEventHandler) {
+  removeA11yEventListener(aEventType, aEventHandler);
+  listenA11yEvents(false);
+}
+
+// //////////////////////////////////////////////////////////////////////////////
+// Event queue
+
+/**
+ * Return value of invoke method of invoker object. Indicates invoker was unable
+ * to prepare action.
+ */
+const INVOKER_ACTION_FAILED = 1;
+
+/**
+ * Return value of eventQueue.onFinish. Indicates eventQueue should not finish
+ * tests.
+ */
+const DO_NOT_FINISH_TEST = 1;
+
+/**
+ * Creates event queue for the given event type. The queue consists of invoker
+ * objects, each of them generates the event of the event type. When queue is
+ * started then every invoker object is asked to generate event after timeout.
+ * When event is caught then current invoker object is asked to check whether
+ * event was handled correctly.
+ *
+ * Invoker interface is:
+ *
+ *   var invoker = {
+ *     // Generates accessible event or event sequence. If returns
+ *     // INVOKER_ACTION_FAILED constant then stop tests.
+ *     invoke: function(){},
+ *
+ *     // [optional] Invoker's check of handled event for correctness.
+ *     check: function(aEvent){},
+ *
+ *     // [optional] Invoker's check before the next invoker is proceeded.
+ *     finalCheck: function(aEvent){},
+ *
+ *     // [optional] Is called when event of any registered type is handled.
+ *     debugCheck: function(aEvent){},
+ *
+ *     // [ignored if 'eventSeq' is defined] DOM node event is generated for
+ *     // (used in the case when invoker expects single event).
+ *     DOMNode getter: function() {},
+ *
+ *     // [optional] if true then event sequences are ignored (no failure if
+ *     // sequences are empty). Use you need to invoke an action, do some check
+ *     // after timeout and proceed a next invoker.
+ *     noEventsOnAction getter: function() {},
+ *
+ *     // Array of checker objects defining expected events on invoker's action.
+ *     //
+ *     // Checker object interface:
+ *     //
+ *     // var checker = {
+ *     //   * DOM or a11y event type. *
+ *     //   type getter: function() {},
+ *     //
+ *     //   * DOM node or accessible. *
+ *     //   target getter: function() {},
+ *     //
+ *     //   * DOM event phase (false - bubbling). *
+ *     //   phase getter: function() {},
+ *     //
+ *     //   * Callback, called to match handled event. *
+ *     //   match : function(aEvent) {},
+ *     //
+ *     //   * Callback, called when event is handled
+ *     //   check: function(aEvent) {},
+ *     //
+ *     //   * Checker ID *
+ *     //   getID: function() {},
+ *     //
+ *     //   * Event that don't have predefined order relative other events. *
+ *     //   async getter: function() {},
+ *     //
+ *     //   * Event that is not expected. *
+ *     //   unexpected getter: function() {},
+ *     //
+ *     //   * No other event of the same type is not allowed. *
+ *     //   unique getter: function() {}
+ *     // };
+ *     eventSeq getter() {},
+ *
+ *     // Array of checker objects defining unexpected events on invoker's
+ *     // action.
+ *     unexpectedEventSeq getter() {},
+ *
+ *     // The ID of invoker.
+ *     getID: function(){} // returns invoker ID
+ *   };
+ *
+ *   // Used to add a possible scenario of expected/unexpected events on
+ *   // invoker's action.
+ *  defineScenario(aInvokerObj, aEventSeq, aUnexpectedEventSeq)
+ *
+ *
+ * @param  aEventType  [in, optional] the default event type (isn't used if
+ *                      invoker defines eventSeq property).
+ */
+function eventQueue(aEventType) {
+  // public
+
+  /**
+   * Add invoker object into queue.
+   */
+  this.push = function eventQueue_push(aEventInvoker) {
+    this.mInvokers.push(aEventInvoker);
+  };
+
+  /**
+   * Start the queue processing.
+   */
+  this.invoke = function eventQueue_invoke() {
+    listenA11yEvents(true);
+
+    // XXX: Intermittent test_events_caretmove.html fails withouth timeout,
+    // see bug 474952.
+    this.processNextInvokerInTimeout(true);
+  };
+
+  /**
+   * This function is called when all events in the queue were handled.
+   * Override it if you need to be notified of this.
+   */
+  this.onFinish = function eventQueue_finish() {};
+
+  // private
+
+  /**
+   * Process next invoker.
+   */
+  // eslint-disable-next-line complexity
+  this.processNextInvoker = function eventQueue_processNextInvoker() {
+    // Some scenario was matched, we wait on next invoker processing.
+    if (this.mNextInvokerStatus == kInvokerCanceled) {
+      this.setInvokerStatus(
+        kInvokerNotScheduled,
+        "scenario was matched, wait for next invoker activation"
+      );
+      return;
+    }
+
+    this.setInvokerStatus(
+      kInvokerNotScheduled,
+      "the next invoker is processed now"
+    );
+
+    // Finish processing of the current invoker if any.
+    var testFailed = false;
+
+    var invoker = this.getInvoker();
+    if (invoker) {
+      if ("finalCheck" in invoker) {
+        invoker.finalCheck();
+      }
+
+      if (this.mScenarios && this.mScenarios.length) {
+        var matchIdx = -1;
+        for (var scnIdx = 0; scnIdx < this.mScenarios.length; scnIdx++) {
+          var eventSeq = this.mScenarios[scnIdx];
+          if (!this.areExpectedEventsLeft(eventSeq)) {
+            for (var idx = 0; idx < eventSeq.length; idx++) {
+              var checker = eventSeq[idx];
+              if (
+                (checker.unexpected && checker.wasCaught) ||
+                (!checker.unexpected && checker.wasCaught != 1)
+              ) {
+                break;
+              }
+            }
+
+            // Ok, we have matched scenario. Report it was completed ok. In
+            // case of empty scenario guess it was matched but if later we
+            // find out that non empty scenario was matched then it will be
+            // a final match.
+            if (idx == eventSeq.length) {
+              if (
+                matchIdx != -1 &&
+                !!eventSeq.length &&
+                this.mScenarios[matchIdx].length
+              ) {
+                ok(
+                  false,
+                  "We have a matched scenario at index " +
+                    matchIdx +
+                    " already."
+                );
+              }
+
+              if (matchIdx == -1 || eventSeq.length) {
+                matchIdx = scnIdx;
+              }
+
+              // Report everything is ok.
+              for (var idx = 0; idx < eventSeq.length; idx++) {
+                var checker = eventSeq[idx];
+
+                var typeStr = eventQueue.getEventTypeAsString(checker);
+                var msg =
+                  "Test with ID = '" + this.getEventID(checker) + "' succeed. ";
+
+                if (checker.unexpected) {
+                  ok(true, msg + `There's no unexpected '${typeStr}' event.`);
+                } else if (checker.todo) {
+                  todo(false, `Todo event '${typeStr}' was caught`);
+                } else {
+                  ok(true, `${msg} Event '${typeStr}' was handled.`);
+                }
+              }
+            }
+          }
+        }
+
+        // We don't have completely matched scenario. Report each failure/success
+        // for every scenario.
+        if (matchIdx == -1) {
+          testFailed = true;
+          for (var scnIdx = 0; scnIdx < this.mScenarios.length; scnIdx++) {
+            var eventSeq = this.mScenarios[scnIdx];
+            for (var idx = 0; idx < eventSeq.length; idx++) {
+              var checker = eventSeq[idx];
+
+              var typeStr = eventQueue.getEventTypeAsString(checker);
+              var msg =
+                "Scenario #" +
+                scnIdx +
+                " of test with ID = '" +
+                this.getEventID(checker) +
+                "' failed. ";
+
+              if (checker.wasCaught > 1) {
+                ok(false, msg + "Dupe " + typeStr + " event.");
+              }
+
+              if (checker.unexpected) {
+                if (checker.wasCaught) {
+                  ok(false, msg + "There's unexpected " + typeStr + " event.");
+                }
+              } else if (!checker.wasCaught) {
+                var rf = checker.todo ? todo : ok;
+                rf(false, `${msg} '${typeStr} event is missed.`);
+              }
+            }
+          }
+        }
+      }
+    }
+
+    this.clearEventHandler();
+
+    // Check if need to stop the test.
+    if (testFailed || this.mIndex == this.mInvokers.length - 1) {
+      listenA11yEvents(false);
+
+      var res = this.onFinish();
+      if (res != DO_NOT_FINISH_TEST) {
+        SimpleTest.executeSoon(SimpleTest.finish);
+      }
+
+      return;
+    }
+
+    // Start processing of next invoker.
+    invoker = this.getNextInvoker();
+
+    // Set up event listeners. Process a next invoker if no events were added.
+    if (!this.setEventHandler(invoker)) {
+      this.processNextInvoker();
+      return;
+    }
+
+    if (gLogger.isEnabled()) {
+      gLogger.logToConsole("Event queue: \n  invoke: " + invoker.getID());
+      gLogger.logToDOM("EQ: invoke: " + invoker.getID(), true);
+    }
+
+    var infoText = "Invoke the '" + invoker.getID() + "' test { ";
+    var scnCount = this.mScenarios ? this.mScenarios.length : 0;
+    for (var scnIdx = 0; scnIdx < scnCount; scnIdx++) {
+      infoText += "scenario #" + scnIdx + ": ";
+      var eventSeq = this.mScenarios[scnIdx];
+      for (var idx = 0; idx < eventSeq.length; idx++) {
+        infoText += eventSeq[idx].unexpected
+          ? "un"
+          : "" +
+            "expected '" +
+            eventQueue.getEventTypeAsString(eventSeq[idx]) +
+            "' event; ";
+      }
+    }
+    infoText += " }";
+    info(infoText);
+
+    if (invoker.invoke() == INVOKER_ACTION_FAILED) {
+      // Invoker failed to prepare action, fail and finish tests.
+      this.processNextInvoker();
+      return;
+    }
+
+    if (this.hasUnexpectedEventsScenario()) {
+      this.processNextInvokerInTimeout(true);
+    }
+  };
+
+  this.processNextInvokerInTimeout =
+    function eventQueue_processNextInvokerInTimeout(aUncondProcess) {
+      this.setInvokerStatus(kInvokerPending, "Process next invoker in timeout");
+
+      // No need to wait extra timeout when a) we know we don't need to do that
+      // and b) there's no any single unexpected event.
+      if (!aUncondProcess && this.areAllEventsExpected()) {
+        // We need delay to avoid events coalesce from different invokers.
+        var queue = this;
+        SimpleTest.executeSoon(function () {
+          queue.processNextInvoker();
+        });
+        return;
+      }
+
+      // Check in timeout invoker didn't fire registered events.
+      window.setTimeout(
+        function (aQueue) {
+          aQueue.processNextInvoker();
+        },
+        300,
+        this
+      );
+    };
+
+  /**
+   * Handle events for the current invoker.
+   */
+  // eslint-disable-next-line complexity
+  this.handleEvent = function eventQueue_handleEvent(aEvent) {
+    var invoker = this.getInvoker();
+    if (!invoker) {
+      // skip events before test was started
+      return;
+    }
+
+    if (!this.mScenarios) {
+      // Bad invoker object, error will be reported before processing of next
+      // invoker in the queue.
+      this.processNextInvoker();
+      return;
+    }
+
+    if ("debugCheck" in invoker) {
+      invoker.debugCheck(aEvent);
+    }
+
+    for (var scnIdx = 0; scnIdx < this.mScenarios.length; scnIdx++) {
+      var eventSeq = this.mScenarios[scnIdx];
+      for (var idx = 0; idx < eventSeq.length; idx++) {
+        var checker = eventSeq[idx];
+
+        // Search through handled expected events to report error if one of them
+        // is handled for a second time.
+        if (
+          !checker.unexpected &&
+          checker.wasCaught > 0 &&
+          eventQueue.isSameEvent(checker, aEvent)
+        ) {
+          checker.wasCaught++;
+          continue;
+        }
+
+        // Search through unexpected events, any match results in error report
+        // after this invoker processing (in case of matched scenario only).
+        if (checker.unexpected && eventQueue.compareEvents(checker, aEvent)) {
+          checker.wasCaught++;
+          continue;
+        }
+
+        // Report an error if we handled not expected event of unique type
+        // (i.e. event types are matched, targets differs).
+        if (
+          !checker.unexpected &&
+          checker.unique &&
+          eventQueue.compareEventTypes(checker, aEvent)
+        ) {
+          var isExpected = false;
+          for (var jdx = 0; jdx < eventSeq.length; jdx++) {
+            isExpected = eventQueue.compareEvents(eventSeq[jdx], aEvent);
+            if (isExpected) {
+              break;
+            }
+          }
+
+          if (!isExpected) {
+            ok(
+              false,
+              "Unique type " +
+                eventQueue.getEventTypeAsString(checker) +
+                " event was handled."
+            );
+          }
+        }
+      }
+    }
+
+    var hasMatchedCheckers = false;
+    for (var scnIdx = 0; scnIdx < this.mScenarios.length; scnIdx++) {
+      var eventSeq = this.mScenarios[scnIdx];
+
+      // Check if handled event matches expected sync event.
+      var nextChecker = this.getNextExpectedEvent(eventSeq);
+      if (nextChecker) {
+        if (eventQueue.compareEvents(nextChecker, aEvent)) {
+          this.processMatchedChecker(aEvent, nextChecker, scnIdx, eventSeq.idx);
+          hasMatchedCheckers = true;
+          continue;
+        }
+      }
+
+      // Check if handled event matches any expected async events.
+      var haveUnmatchedAsync = false;
+      for (idx = 0; idx < eventSeq.length; idx++) {
+        if (eventSeq[idx] instanceof orderChecker && haveUnmatchedAsync) {
+          break;
+        }
+
+        if (!eventSeq[idx].wasCaught) {
+          haveUnmatchedAsync = true;
+        }
+
+        if (!eventSeq[idx].unexpected && eventSeq[idx].async) {
+          if (eventQueue.compareEvents(eventSeq[idx], aEvent)) {
+            this.processMatchedChecker(aEvent, eventSeq[idx], scnIdx, idx);
+            hasMatchedCheckers = true;
+            break;
+          }
+        }
+      }
+    }
+
+    if (hasMatchedCheckers) {
+      var invoker = this.getInvoker();
+      if ("check" in invoker) {
+        invoker.check(aEvent);
+      }
+    }
+
+    for (idx = 0; idx < eventSeq.length; idx++) {
+      if (!eventSeq[idx].wasCaught) {
+        if (eventSeq[idx] instanceof orderChecker) {
+          eventSeq[idx].wasCaught++;
+        } else {
+          break;
+        }
+      }
+    }
+
+    // If we don't have more events to wait then schedule next invoker.
+    if (this.hasMatchedScenario()) {
+      if (this.mNextInvokerStatus == kInvokerNotScheduled) {
+        this.processNextInvokerInTimeout();
+      } else if (this.mNextInvokerStatus == kInvokerCanceled) {
+        this.setInvokerStatus(
+          kInvokerPending,
+          "Full match. Void the cancelation of next invoker processing"
+        );
+      }
+      return;
+    }
+
+    // If we have scheduled a next invoker then cancel in case of match.
+    if (this.mNextInvokerStatus == kInvokerPending && hasMatchedCheckers) {
+      this.setInvokerStatus(
+        kInvokerCanceled,
+        "Cancel the scheduled invoker in case of match"
+      );
+    }
+  };
+
+  // Helpers
+  this.processMatchedChecker = function eventQueue_function(
+    aEvent,
+    aMatchedChecker,
+    aScenarioIdx,
+    aEventIdx
+  ) {
+    aMatchedChecker.wasCaught++;
+
+    if ("check" in aMatchedChecker) {
+      aMatchedChecker.check(aEvent);
+    }
+
+    eventQueue.logEvent(
+      aEvent,
+      aMatchedChecker,
+      aScenarioIdx,
+      aEventIdx,
+      this.areExpectedEventsLeft(),
+      this.mNextInvokerStatus
+    );
+  };
+
+  this.getNextExpectedEvent = function eventQueue_getNextExpectedEvent(
+    aEventSeq
+  ) {
+    if (!("idx" in aEventSeq)) {
+      aEventSeq.idx = 0;
+    }
+
+    while (
+      aEventSeq.idx < aEventSeq.length &&
+      (aEventSeq[aEventSeq.idx].unexpected ||
+        aEventSeq[aEventSeq.idx].todo ||
+        aEventSeq[aEventSeq.idx].async ||
+        aEventSeq[aEventSeq.idx] instanceof orderChecker ||
+        aEventSeq[aEventSeq.idx].wasCaught > 0)
+    ) {
+      aEventSeq.idx++;
+    }
+
+    return aEventSeq.idx != aEventSeq.length ? aEventSeq[aEventSeq.idx] : null;
+  };
+
+  this.areExpectedEventsLeft = function eventQueue_areExpectedEventsLeft(
+    aScenario
+  ) {
+    function scenarioHasUnhandledExpectedEvent(aEventSeq) {
+      // Check if we have unhandled async (can be anywhere in the sequance) or
+      // sync expcected events yet.
+      for (var idx = 0; idx < aEventSeq.length; idx++) {
+        if (
+          !aEventSeq[idx].unexpected &&
+          !aEventSeq[idx].todo &&
+          !aEventSeq[idx].wasCaught &&
+          !(aEventSeq[idx] instanceof orderChecker)
+        ) {
+          return true;
+        }
+      }
+
+      return false;
+    }
+
+    if (aScenario) {
+      return scenarioHasUnhandledExpectedEvent(aScenario);
+    }
+
+    for (var scnIdx = 0; scnIdx < this.mScenarios.length; scnIdx++) {
+      var eventSeq = this.mScenarios[scnIdx];
+      if (scenarioHasUnhandledExpectedEvent(eventSeq)) {
+        return true;
+      }
+    }
+    return false;
+  };
+
+  this.areAllEventsExpected = function eventQueue_areAllEventsExpected() {
+    for (var scnIdx = 0; scnIdx < this.mScenarios.length; scnIdx++) {
+      var eventSeq = this.mScenarios[scnIdx];
+      for (var idx = 0; idx < eventSeq.length; idx++) {
+        if (eventSeq[idx].unexpected || eventSeq[idx].todo) {
+          return false;
+        }
+      }
+    }
+
+    return true;
+  };
+
+  this.isUnexpectedEventScenario =
+    function eventQueue_isUnexpectedEventsScenario(aScenario) {
+      for (var idx = 0; idx < aScenario.length; idx++) {
+        if (!aScenario[idx].unexpected && !aScenario[idx].todo) {
+          break;
+        }
+      }
+
+      return idx == aScenario.length;
+    };
+
+  this.hasUnexpectedEventsScenario =
+    function eventQueue_hasUnexpectedEventsScenario() {
+      if (this.getInvoker().noEventsOnAction) {
+        return true;
+      }
+
+      for (var scnIdx = 0; scnIdx < this.mScenarios.length; scnIdx++) {
+        if (this.isUnexpectedEventScenario(this.mScenarios[scnIdx])) {
+          return true;
+        }
+      }
+
+      return false;
+    };
+
+  this.hasMatchedScenario = function eventQueue_hasMatchedScenario() {
+    for (var scnIdx = 0; scnIdx < this.mScenarios.length; scnIdx++) {
+      var scn = this.mScenarios[scnIdx];
+      if (
+        !this.isUnexpectedEventScenario(scn) &&
+        !this.areExpectedEventsLeft(scn)
+      ) {
+        return true;
+      }
+    }
+    return false;
+  };
+
+  this.getInvoker = function eventQueue_getInvoker() {
+    return this.mInvokers[this.mIndex];
+  };
+
+  this.getNextInvoker = function eventQueue_getNextInvoker() {
+    return this.mInvokers[++this.mIndex];
+  };
+
+  this.setEventHandler = function eventQueue_setEventHandler(aInvoker) {
+    if (!("scenarios" in aInvoker) || !aInvoker.scenarios.length) {
+      var eventSeq = aInvoker.eventSeq;
+      var unexpectedEventSeq = aInvoker.unexpectedEventSeq;
+      if (!eventSeq && !unexpectedEventSeq && this.mDefEventType) {
+        eventSeq = [new invokerChecker(this.mDefEventType, aInvoker.DOMNode)];
+      }
+
+      if (eventSeq || unexpectedEventSeq) {
+        defineScenario(aInvoker, eventSeq, unexpectedEventSeq);
+      }
+    }
+
+    if (aInvoker.noEventsOnAction) {
+      return true;
+    }
+
+    this.mScenarios = aInvoker.scenarios;
+    if (!this.mScenarios || !this.mScenarios.length) {
+      ok(false, "Broken invoker '" + aInvoker.getID() + "'");
+      return false;
+    }
+
+    // Register event listeners.
+    for (var scnIdx = 0; scnIdx < this.mScenarios.length; scnIdx++) {
+      var eventSeq = this.mScenarios[scnIdx];
+
+      if (gLogger.isEnabled()) {
+        var msg =
+          "scenario #" +
+          scnIdx +
+          ", registered events number: " +
+          eventSeq.length;
+        gLogger.logToConsole(msg);
+        gLogger.logToDOM(msg, true);
+      }
+
+      // Do not warn about empty event sequances when more than one scenario
+      // was registered.
+      if (this.mScenarios.length == 1 && !eventSeq.length) {
+        ok(
+          false,
+          "Broken scenario #" +
+            scnIdx +
+            " of invoker '" +
+            aInvoker.getID() +
+            "'. No registered events"
+        );
+        return false;
+      }
+
+      for (var idx = 0; idx < eventSeq.length; idx++) {
+        eventSeq[idx].wasCaught = 0;
+      }
+
+      for (var idx = 0; idx < eventSeq.length; idx++) {
+        if (gLogger.isEnabled()) {
+          var msg = "registered";
+          if (eventSeq[idx].unexpected) {
+            msg += " unexpected";
+          }
+          if (eventSeq[idx].async) {
+            msg += " async";
+          }
+
+          msg +=
+            ": event type: " +
+            eventQueue.getEventTypeAsString(eventSeq[idx]) +
+            ", target: " +
+            eventQueue.getEventTargetDescr(eventSeq[idx], true);
+
+          gLogger.logToConsole(msg);
+          gLogger.logToDOM(msg, true);
+        }
+
+        var eventType = eventSeq[idx].type;
+        if (typeof eventType == "string") {
+          // DOM event
+          var target = eventQueue.getEventTarget(eventSeq[idx]);
+          if (!target) {
+            ok(false, "no target for DOM event!");
+            return false;
+          }
+          var phase = eventQueue.getEventPhase(eventSeq[idx]);
+          target.addEventListener(eventType, this, phase);
+        } else {
+          // A11y event
+          addA11yEventListener(eventType, this);
+        }
+      }
+    }
+
+    return true;
+  };
+
+  this.clearEventHandler = function eventQueue_clearEventHandler() {
+    if (!this.mScenarios) {
+      return;
+    }
+
+    for (var scnIdx = 0; scnIdx < this.mScenarios.length; scnIdx++) {
+      var eventSeq = this.mScenarios[scnIdx];
+      for (var idx = 0; idx < eventSeq.length; idx++) {
+        var eventType = eventSeq[idx].type;
+        if (typeof eventType == "string") {
+          // DOM event
+          var target = eventQueue.getEventTarget(eventSeq[idx]);
+          var phase = eventQueue.getEventPhase(eventSeq[idx]);
+          target.removeEventListener(eventType, this, phase);
+        } else {
+          // A11y event
+          removeA11yEventListener(eventType, this);
+        }
+      }
+    }
+    this.mScenarios = null;
+  };
+
+  this.getEventID = function eventQueue_getEventID(aChecker) {
+    if ("getID" in aChecker) {
+      return aChecker.getID();
+    }
+
+    var invoker = this.getInvoker();
+    return invoker.getID();
+  };
+
+  this.setInvokerStatus = function eventQueue_setInvokerStatus(
+    aStatus,
+    aLogMsg
+  ) {
+    this.mNextInvokerStatus = aStatus;
+
+    // Uncomment it to debug invoker processing logic.
+    // gLogger.log(eventQueue.invokerStatusToMsg(aStatus, aLogMsg));
+  };
+
+  this.mDefEventType = aEventType;
+
+  this.mInvokers = [];
+  this.mIndex = -1;
+  this.mScenarios = null;
+
+  this.mNextInvokerStatus = kInvokerNotScheduled;
+}
+
+// //////////////////////////////////////////////////////////////////////////////
+// eventQueue static members and constants
+
+const kInvokerNotScheduled = 0;
+const kInvokerPending = 1;
+const kInvokerCanceled = 2;
+
+eventQueue.getEventTypeAsString = function eventQueue_getEventTypeAsString(
+  aEventOrChecker
+) {
+  if (Event.isInstance(aEventOrChecker)) {
+    return aEventOrChecker.type;
+  }
+
+  if (aEventOrChecker instanceof nsIAccessibleEvent) {
+    return eventTypeToString(aEventOrChecker.eventType);
+  }
+
+  return typeof aEventOrChecker.type == "string"
+    ? aEventOrChecker.type
+    : eventTypeToString(aEventOrChecker.type);
+};
+
+eventQueue.getEventTargetDescr = function eventQueue_getEventTargetDescr(
+  aEventOrChecker,
+  aDontForceTarget
+) {
+  if (Event.isInstance(aEventOrChecker)) {
+    return prettyName(aEventOrChecker.originalTarget);
+  }
+
+  // XXXbz this block doesn't seem to be reachable...
+  if (Event.isInstance(aEventOrChecker)) {
+    return prettyName(aEventOrChecker.accessible);
+  }
+
+  var descr = aEventOrChecker.targetDescr;
+  if (descr) {
+    return descr;
+  }
+
+  if (aDontForceTarget) {
+    return "no target description";
+  }
+
+  var target = "target" in aEventOrChecker ? aEventOrChecker.target : null;
+  return prettyName(target);
+};
+
+eventQueue.getEventPhase = function eventQueue_getEventPhase(aChecker) {
+  return "phase" in aChecker ? aChecker.phase : true;
+};
+
+eventQueue.getEventTarget = function eventQueue_getEventTarget(aChecker) {
+  if ("eventTarget" in aChecker) {
+    switch (aChecker.eventTarget) {
+      case "element":
+        return aChecker.target;
+      case "document":
+      default:
+        return aChecker.target.ownerDocument;
+    }
+  }
+  return aChecker.target.ownerDocument;
+};
+
+eventQueue.compareEventTypes = function eventQueue_compareEventTypes(
+  aChecker,
+  aEvent
+) {
+  var eventType = Event.isInstance(aEvent) ? aEvent.type : aEvent.eventType;
+  return aChecker.type == eventType;
+};
+
+eventQueue.compareEvents = function eventQueue_compareEvents(aChecker, aEvent) {
+  if (!eventQueue.compareEventTypes(aChecker, aEvent)) {
+    return false;
+  }
+
+  // If checker provides "match" function then allow the checker to decide
+  // whether event is matched.
+  if ("match" in aChecker) {
+    return aChecker.match(aEvent);
+  }
+
+  var target1 = aChecker.target;
+  if (target1 instanceof nsIAccessible) {
+    var target2 = Event.isInstance(aEvent)
+      ? getAccessible(aEvent.target)
+      : aEvent.accessible;
+
+    return target1 == target2;
+  }
+
+  // If original target isn't suitable then extend interface to support target
+  // (original target is used in test_elm_media.html).
+  var target2 = Event.isInstance(aEvent)
+    ? aEvent.originalTarget
+    : aEvent.DOMNode;
+  return target1 == target2;
+};
+
+eventQueue.isSameEvent = function eventQueue_isSameEvent(aChecker, aEvent) {
+  // We don't have stored info about handled event other than its type and
+  // target, thus we should filter text change and state change events since
+  // they may occur on the same element because of complex changes.
+  return (
+    this.compareEvents(aChecker, aEvent) &&
+    !(aEvent instanceof nsIAccessibleTextChangeEvent) &&
+    !(aEvent instanceof nsIAccessibleStateChangeEvent)
+  );
+};
+
+eventQueue.invokerStatusToMsg = function eventQueue_invokerStatusToMsg(
+  aInvokerStatus,
+  aMsg
+) {
+  var msg = "invoker status: ";
+  switch (aInvokerStatus) {
+    case kInvokerNotScheduled:
+      msg += "not scheduled";
+      break;
+    case kInvokerPending:
+      msg += "pending";
+      break;
+    case kInvokerCanceled:
+      msg += "canceled";
+      break;
+  }
+
+  if (aMsg) {
+    msg += " (" + aMsg + ")";
+  }
+
+  return msg;
+};
+
+eventQueue.logEvent = function eventQueue_logEvent(
+  aOrigEvent,
+  aMatchedChecker,
+  aScenarioIdx,
+  aEventIdx,
+  aAreExpectedEventsLeft,
+  aInvokerStatus
+) {
+  // Dump DOM event information. Skip a11y event since it is dumped by
+  // gA11yEventObserver.
+  if (Event.isInstance(aOrigEvent)) {
+    var info = "Event type: " + eventQueue.getEventTypeAsString(aOrigEvent);
+    info += ". Target: " + eventQueue.getEventTargetDescr(aOrigEvent);
+    gLogger.logToDOM(info);
+  }
+
+  var infoMsg =
+    "unhandled expected events: " +
+    aAreExpectedEventsLeft +
+    ", " +
+    eventQueue.invokerStatusToMsg(aInvokerStatus);
+
+  var currType = eventQueue.getEventTypeAsString(aMatchedChecker);
+  var currTargetDescr = eventQueue.getEventTargetDescr(aMatchedChecker);
+  var consoleMsg =
+    "*****\nScenario " +
+    aScenarioIdx +
+    ", event " +
+    aEventIdx +
+    " matched: " +
+    currType +
+    "\n" +
+    infoMsg +
+    "\n*****";
+  gLogger.logToConsole(consoleMsg);
+
+  var emphText = "matched ";
+  var msg =
+    "EQ event, type: " +
+    currType +
+    ", target: " +
+    currTargetDescr +
+    ", " +
+    infoMsg;
+  gLogger.logToDOM(msg, true, emphText);
+};
+
+// //////////////////////////////////////////////////////////////////////////////
+// Action sequence
+
+/**
+ * Deal with action sequence. Used when you need to execute couple of actions
+ * each after other one.
+ */
+function sequence() {
+  /**
+   * Append new sequence item.
+   *
+   * @param  aProcessor  [in] object implementing interface
+   *                      {
+   *                        // execute item action
+   *                        process: function() {},
+   *                        // callback, is called when item was processed
+   *                        onProcessed: function() {}
+   *                      };
+   * @param  aEventType  [in] event type of expected event on item action
+   * @param  aTarget     [in] event target of expected event on item action
+   * @param  aItemID     [in] identifier of item
+   */
+  this.append = function sequence_append(
+    aProcessor,
+    aEventType,
+    aTarget,
+    aItemID
+  ) {
+    var item = new sequenceItem(aProcessor, aEventType, aTarget, aItemID);
+    this.items.push(item);
+  };
+
+  /**
+   * Process next sequence item.
+   */
+  this.processNext = function sequence_processNext() {
+    this.idx++;
+    if (this.idx >= this.items.length) {
+      ok(false, "End of sequence: nothing to process!");
+      SimpleTest.finish();
+      return;
+    }
+
+    this.items[this.idx].startProcess();
+  };
+
+  this.items = [];
+  this.idx = -1;
+}
+
+// //////////////////////////////////////////////////////////////////////////////
+// Event queue invokers
+
+/**
+ * Defines a scenario of expected/unexpected events. Each invoker can have
+ * one or more scenarios of events. Only one scenario must be completed.
+ */
+function defineScenario(aInvoker, aEventSeq, aUnexpectedEventSeq) {
+  if (!("scenarios" in aInvoker)) {
+    aInvoker.scenarios = [];
+  }
+
+  // Create unified event sequence concatenating expected and unexpected
+  // events.
+  if (!aEventSeq) {
+    aEventSeq = [];
+  }
+
+  for (var idx = 0; idx < aEventSeq.length; idx++) {
+    aEventSeq[idx].unexpected |= false;
+    aEventSeq[idx].async |= false;
+  }
+
+  if (aUnexpectedEventSeq) {
+    for (var idx = 0; idx < aUnexpectedEventSeq.length; idx++) {
+      aUnexpectedEventSeq[idx].unexpected = true;
+      aUnexpectedEventSeq[idx].async = false;
+    }
+
+    aEventSeq = aEventSeq.concat(aUnexpectedEventSeq);
+  }
+
+  aInvoker.scenarios.push(aEventSeq);
+}
+
+/**
+ * Invokers defined below take a checker object (or array of checker objects).
+ * An invoker listens for default event type registered in event queue object
+ * until its checker is provided.
+ *
+ * Note, checker object or array of checker objects is optional.
+ */
+
+/**
+ * Click invoker.
+ */
+function synthClick(aNodeOrID, aCheckerOrEventSeq, aArgs) {
+  this.__proto__ = new synthAction(aNodeOrID, aCheckerOrEventSeq);
+
+  this.invoke = function synthClick_invoke() {
+    var targetNode = this.DOMNode;
+    if (targetNode.nodeType == targetNode.DOCUMENT_NODE) {
+      targetNode = this.DOMNode.body
+        ? this.DOMNode.body
+        : this.DOMNode.documentElement;
+    }
+
+    // Scroll the node into view, otherwise synth click may fail.
+    if (isHTMLElement(targetNode)) {
+      targetNode.scrollIntoView(true);
+    } else if (isXULElement(targetNode)) {
+      var targetAcc = getAccessible(targetNode);
+      targetAcc.scrollTo(SCROLL_TYPE_ANYWHERE);
+    }
+
+    var x = 1,
+      y = 1;
+    if (aArgs && "where" in aArgs) {
+      if (aArgs.where == "right") {
+        if (isHTMLElement(targetNode)) {
+          x = targetNode.offsetWidth - 1;
+        } else if (isXULElement(targetNode)) {
+          x = targetNode.getBoundingClientRect().width - 1;
+        }
+      } else if (aArgs.where == "center") {
+        if (isHTMLElement(targetNode)) {
+          x = targetNode.offsetWidth / 2;
+          y = targetNode.offsetHeight / 2;
+        } else if (isXULElement(targetNode)) {
+          x = targetNode.getBoundingClientRect().width / 2;
+          y = targetNode.getBoundingClientRect().height / 2;
+        }
+      }
+    }
+    synthesizeMouse(targetNode, x, y, aArgs ? aArgs : {});
+  };
+
+  this.finalCheck = function synthClick_finalCheck() {
+    // Scroll top window back.
+    window.top.scrollTo(0, 0);
+  };
+
+  this.getID = function synthClick_getID() {
+    return prettyName(aNodeOrID) + " click";
+  };
+}
+
+/**
+ * Scrolls the node into view.
+ */
+function scrollIntoView(aNodeOrID, aCheckerOrEventSeq) {
+  this.__proto__ = new synthAction(aNodeOrID, aCheckerOrEventSeq);
+
+  this.invoke = function scrollIntoView_invoke() {
+    var targetNode = this.DOMNode;
+    if (isHTMLElement(targetNode)) {
+      targetNode.scrollIntoView(true);
+    } else if (isXULElement(targetNode)) {
+      var targetAcc = getAccessible(targetNode);
+      targetAcc.scrollTo(SCROLL_TYPE_ANYWHERE);
+    }
+  };
+
+  this.getID = function scrollIntoView_getID() {
+    return prettyName(aNodeOrID) + " scrollIntoView";
+  };
+}
+
+/**
+ * Mouse move invoker.
+ */
+function synthMouseMove(aID, aCheckerOrEventSeq) {
+  this.__proto__ = new synthAction(aID, aCheckerOrEventSeq);
+
+  this.invoke = function synthMouseMove_invoke() {
+    synthesizeMouse(this.DOMNode, 5, 5, { type: "mousemove" });
+    synthesizeMouse(this.DOMNode, 6, 6, { type: "mousemove" });
+  };
+
+  this.getID = function synthMouseMove_getID() {
+    return prettyName(aID) + " mouse move";
+  };
+}
+
+/**
+ * General key press invoker.
+ */
+function synthKey(aNodeOrID, aKey, aArgs, aCheckerOrEventSeq) {
+  this.__proto__ = new synthAction(aNodeOrID, aCheckerOrEventSeq);
+
+  this.invoke = function synthKey_invoke() {
+    synthesizeKey(this.mKey, this.mArgs, this.mWindow);
+  };
+
+  this.getID = function synthKey_getID() {
+    var key = this.mKey;
+    switch (this.mKey) {
+      case "VK_TAB":
+        key = "tab";
+        break;
+      case "VK_DOWN":
+        key = "down";
+        break;
+      case "VK_UP":
+        key = "up";
+        break;
+      case "VK_LEFT":
+        key = "left";
+        break;
+      case "VK_RIGHT":
+        key = "right";
+        break;
+      case "VK_HOME":
+        key = "home";
+        break;
+      case "VK_END":
+        key = "end";
+        break;
+      case "VK_ESCAPE":
+        key = "escape";
+        break;
+      case "VK_RETURN":
+        key = "enter";
+        break;
+    }
+    if (aArgs) {
+      if (aArgs.shiftKey) {
+        key += " shift";
+      }
+      if (aArgs.ctrlKey) {
+        key += " ctrl";
+      }
+      if (aArgs.altKey) {
+        key += " alt";
+      }
+    }
+    return prettyName(aNodeOrID) + " '" + key + " ' key";
+  };
+
+  this.mKey = aKey;
+  this.mArgs = aArgs ? aArgs : {};
+  this.mWindow = aArgs ? aArgs.window : null;
+}
+
+/**
+ * Tab key invoker.
+ */
+function synthTab(aNodeOrID, aCheckerOrEventSeq, aWindow) {
+  this.__proto__ = new synthKey(
+    aNodeOrID,
+    "VK_TAB",
+    { shiftKey: false, window: aWindow },
+    aCheckerOrEventSeq
+  );
+}
+
+/**
+ * Shift tab key invoker.
+ */
+function synthShiftTab(aNodeOrID, aCheckerOrEventSeq) {
+  this.__proto__ = new synthKey(
+    aNodeOrID,
+    "VK_TAB",
+    { shiftKey: true },
+    aCheckerOrEventSeq
+  );
+}
+
+/**
+ * Escape key invoker.
+ */
+function synthEscapeKey(aNodeOrID, aCheckerOrEventSeq) {
+  this.__proto__ = new synthKey(
+    aNodeOrID,
+    "VK_ESCAPE",
+    null,
+    aCheckerOrEventSeq
+  );
+}
+
+/**
+ * Down arrow key invoker.
+ */
+function synthDownKey(aNodeOrID, aCheckerOrEventSeq, aArgs) {
+  this.__proto__ = new synthKey(
+    aNodeOrID,
+    "VK_DOWN",
+    aArgs,
+    aCheckerOrEventSeq
+  );
+}
+
+/**
+ * Up arrow key invoker.
+ */
+function synthUpKey(aNodeOrID, aCheckerOrEventSeq, aArgs) {
+  this.__proto__ = new synthKey(aNodeOrID, "VK_UP", aArgs, aCheckerOrEventSeq);
+}
+
+/**
+ * Left arrow key invoker.
+ */
+function synthLeftKey(aNodeOrID, aCheckerOrEventSeq, aArgs) {
+  this.__proto__ = new synthKey(
+    aNodeOrID,
+    "VK_LEFT",
+    aArgs,
+    aCheckerOrEventSeq
+  );
+}
+
+/**
+ * Right arrow key invoker.
+ */
+function synthRightKey(aNodeOrID, aCheckerOrEventSeq, aArgs) {
+  this.__proto__ = new synthKey(
+    aNodeOrID,
+    "VK_RIGHT",
+    aArgs,
+    aCheckerOrEventSeq
+  );
+}
+
+/**
+ * Home key invoker.
+ */
+function synthHomeKey(aNodeOrID, aCheckerOrEventSeq) {
+  this.__proto__ = new synthKey(aNodeOrID, "VK_HOME", null, aCheckerOrEventSeq);
+}
+
+/**
+ * End key invoker.
+ */
+function synthEndKey(aNodeOrID, aCheckerOrEventSeq) {
+  this.__proto__ = new synthKey(aNodeOrID, "VK_END", null, aCheckerOrEventSeq);
+}
+
+/**
+ * Enter key invoker
+ */
+function synthEnterKey(aID, aCheckerOrEventSeq) {
+  this.__proto__ = new synthKey(aID, "VK_RETURN", null, aCheckerOrEventSeq);
+}
+
+/**
+ * Synth alt + down arrow to open combobox.
+ */
+function synthOpenComboboxKey(aID, aCheckerOrEventSeq) {
+  this.__proto__ = new synthDownKey(aID, aCheckerOrEventSeq, { altKey: true });
+
+  this.getID = function synthOpenComboboxKey_getID() {
+    return "open combobox (alt + down arrow) " + prettyName(aID);
+  };
+}
+
+/**
+ * Focus invoker.
+ */
+function synthFocus(aNodeOrID, aCheckerOrEventSeq) {
+  var checkerOfEventSeq = aCheckerOrEventSeq
+    ? aCheckerOrEventSeq
+    : new focusChecker(aNodeOrID);
+  this.__proto__ = new synthAction(aNodeOrID, checkerOfEventSeq);
+
+  this.invoke = function synthFocus_invoke() {
+    if (this.DOMNode.editor) {
+      this.DOMNode.selectionStart = this.DOMNode.selectionEnd =
+        this.DOMNode.value.length;
+    }
+    this.DOMNode.focus();
+  };
+
+  this.getID = function synthFocus_getID() {
+    return prettyName(aNodeOrID) + " focus";
+  };
+}
+
+/**
+ * Focus invoker. Focus the HTML body of content document of iframe.
+ */
+function synthFocusOnFrame(aNodeOrID, aCheckerOrEventSeq) {
+  var frameDoc = getNode(aNodeOrID).contentDocument;
+  var checkerOrEventSeq = aCheckerOrEventSeq
+    ? aCheckerOrEventSeq
+    : new focusChecker(frameDoc);
+  this.__proto__ = new synthAction(frameDoc, checkerOrEventSeq);
+
+  this.invoke = function synthFocus_invoke() {
+    this.DOMNode.body.focus();
+  };
+
+  this.getID = function synthFocus_getID() {
+    return prettyName(aNodeOrID) + " frame document focus";
+  };
+}
+
+/**
+ * Change the current item when the widget doesn't have a focus.
+ */
+function changeCurrentItem(aID, aItemID) {
+  this.eventSeq = [new nofocusChecker()];
+
+  this.invoke = function changeCurrentItem_invoke() {
+    var controlNode = getNode(aID);
+    var itemNode = getNode(aItemID);
+
+    // HTML
+    if (controlNode.localName == "input") {
+      if (controlNode.checked) {
+        this.reportError();
+      }
+
+      controlNode.checked = true;
+      return;
+    }
+
+    if (controlNode.localName == "select") {
+      if (controlNode.selectedIndex == itemNode.index) {
+        this.reportError();
+      }
+
+      controlNode.selectedIndex = itemNode.index;
+      return;
+    }
+
+    // XUL
+    if (controlNode.localName == "tree") {
+      if (controlNode.currentIndex == aItemID) {
+        this.reportError();
+      }
+
+      controlNode.currentIndex = aItemID;
+      return;
+    }
+
+    if (controlNode.localName == "menulist") {
+      if (controlNode.selectedItem == itemNode) {
+        this.reportError();
+      }
+
+      controlNode.selectedItem = itemNode;
+      return;
+    }
+
+    if (controlNode.currentItem == itemNode) {
+      ok(
+        false,
+        "Error in test: proposed current item is already current" +
+          prettyName(aID)
+      );
+    }
+
+    controlNode.currentItem = itemNode;
+  };
+
+  this.getID = function changeCurrentItem_getID() {
+    return "current item change for " + prettyName(aID);
+  };
+
+  this.reportError = function changeCurrentItem_reportError() {
+    ok(
+      false,
+      "Error in test: proposed current item '" +
+        aItemID +
+        "' is already current"
+    );
+  };
+}
+
+/**
+ * Toggle top menu invoker.
+ */
+function toggleTopMenu(aID, aCheckerOrEventSeq) {
+  this.__proto__ = new synthKey(aID, "VK_ALT", null, aCheckerOrEventSeq);
+
+  this.getID = function toggleTopMenu_getID() {
+    return "toggle top menu on " + prettyName(aID);
+  };
+}
+
+/**
+ * Context menu invoker.
+ */
+function synthContextMenu(aID, aCheckerOrEventSeq) {
+  this.__proto__ = new synthClick(aID, aCheckerOrEventSeq, {
+    button: 0,
+    type: "contextmenu",
+  });
+
+  this.getID = function synthContextMenu_getID() {
+    return "context menu on " + prettyName(aID);
+  };
+}
+
+/**
+ * Open combobox, autocomplete and etc popup, check expandable states.
+ */
+function openCombobox(aComboboxID) {
+  this.eventSeq = [
+    new stateChangeChecker(STATE_EXPANDED, false, true, aComboboxID),
+  ];
+
+  this.invoke = function openCombobox_invoke() {
+    getNode(aComboboxID).focus();
+    synthesizeKey("VK_DOWN", { altKey: true });
+  };
+
+  this.getID = function openCombobox_getID() {
+    return "open combobox " + prettyName(aComboboxID);
+  };
+}
+
+/**
+ * Close combobox, autocomplete and etc popup, check expandable states.
+ */
+function closeCombobox(aComboboxID) {
+  this.eventSeq = [
+    new stateChangeChecker(STATE_EXPANDED, false, false, aComboboxID),
+  ];
+
+  this.invoke = function closeCombobox_invoke() {
+    synthesizeKey("KEY_Escape");
+  };
+
+  this.getID = function closeCombobox_getID() {
+    return "close combobox " + prettyName(aComboboxID);
+  };
+}
+
+/**
+ * Select all invoker.
+ */
+function synthSelectAll(aNodeOrID, aCheckerOrEventSeq) {
+  this.__proto__ = new synthAction(aNodeOrID, aCheckerOrEventSeq);
+
+  this.invoke = function synthSelectAll_invoke() {
+    if (ChromeUtils.getClassName(this.DOMNode) === "HTMLInputElement") {
+      this.DOMNode.select();
+    } else {
+      window.getSelection().selectAllChildren(this.DOMNode);
+    }
+  };
+
+  this.getID = function synthSelectAll_getID() {
+    return aNodeOrID + " selectall";
+  };
+}
+
+/**
+ * Move the caret to the end of line.
+ */
+function moveToLineEnd(aID, aCaretOffset) {
+  if (MAC) {
+    this.__proto__ = new synthKey(
+      aID,
+      "VK_RIGHT",
+      { metaKey: true },
+      new caretMoveChecker(aCaretOffset, true, aID)
+    );
+  } else {
+    this.__proto__ = new synthEndKey(
+      aID,
+      new caretMoveChecker(aCaretOffset, true, aID)
+    );
+  }
+
+  this.getID = function moveToLineEnd_getID() {
+    return "move to line end in " + prettyName(aID);
+  };
+}
+
+/**
+ * Move the caret to the end of previous line if any.
+ */
+function moveToPrevLineEnd(aID, aCaretOffset) {
+  this.__proto__ = new synthAction(
+    aID,
+    new caretMoveChecker(aCaretOffset, true, aID)
+  );
+
+  this.invoke = function moveToPrevLineEnd_invoke() {
+    synthesizeKey("KEY_ArrowUp");
+
+    if (MAC) {
+      synthesizeKey("Key_ArrowRight", { metaKey: true });
+    } else {
+      synthesizeKey("KEY_End");
+    }
+  };
+
+  this.getID = function moveToPrevLineEnd_getID() {
+    return "move to previous line end in " + prettyName(aID);
+  };
+}
+
+/**
+ * Move the caret to begining of the line.
+ */
+function moveToLineStart(aID, aCaretOffset) {
+  if (MAC) {
+    this.__proto__ = new synthKey(
+      aID,
+      "VK_LEFT",
+      { metaKey: true },
+      new caretMoveChecker(aCaretOffset, true, aID)
+    );
+  } else {
+    this.__proto__ = new synthHomeKey(
+      aID,
+      new caretMoveChecker(aCaretOffset, true, aID)
+    );
+  }
+
+  this.getID = function moveToLineEnd_getID() {
+    return "move to line start in " + prettyName(aID);
+  };
+}
+
+/**
+ * Move the caret to begining of the text.
+ */
+function moveToTextStart(aID) {
+  if (MAC) {
+    this.__proto__ = new synthKey(
+      aID,
+      "VK_UP",
+      { metaKey: true },
+      new caretMoveChecker(0, true, aID)
+    );
+  } else {
+    this.__proto__ = new synthKey(
+      aID,
+      "VK_HOME",
+      { ctrlKey: true },
+      new caretMoveChecker(0, true, aID)
+    );
+  }
+
+  this.getID = function moveToTextStart_getID() {
+    return "move to text start in " + prettyName(aID);
+  };
+}
+
+/**
+ * Move the caret in text accessible.
+ */
+function moveCaretToDOMPoint(
+  aID,
+  aDOMPointNodeID,
+  aDOMPointOffset,
+  aExpectedOffset,
+  aFocusTargetID,
+  aCheckFunc
+) {
+  this.target = getAccessible(aID, [nsIAccessibleText]);
+  this.DOMPointNode = getNode(aDOMPointNodeID);
+  this.focus = aFocusTargetID ? getAccessible(aFocusTargetID) : null;
+  this.focusNode = this.focus ? this.focus.DOMNode : null;
+
+  this.invoke = function moveCaretToDOMPoint_invoke() {
+    if (this.focusNode) {
+      this.focusNode.focus();
+    }
+
+    var selection = this.DOMPointNode.ownerGlobal.getSelection();
+    var selRange = selection.getRangeAt(0);
+    selRange.setStart(this.DOMPointNode, aDOMPointOffset);
+    selRange.collapse(true);
+
+    selection.removeRange(selRange);
+    selection.addRange(selRange);
+  };
+
+  this.getID = function moveCaretToDOMPoint_getID() {
+    return (
+      "Set caret on " +
+      prettyName(aID) +
+      " at point: " +
+      prettyName(aDOMPointNodeID) +
+      " node with offset " +
+      aDOMPointOffset
+    );
+  };
+
+  this.finalCheck = function moveCaretToDOMPoint_finalCheck() {
+    if (aCheckFunc) {
+      aCheckFunc.call();
+    }
+  };
+
+  this.eventSeq = [new caretMoveChecker(aExpectedOffset, true, this.target)];
+
+  if (this.focus) {
+    this.eventSeq.push(new asyncInvokerChecker(EVENT_FOCUS, this.focus));
+  }
+}
+
+/**
+ * Set caret offset in text accessible.
+ */
+function setCaretOffset(aID, aOffset, aFocusTargetID) {
+  this.target = getAccessible(aID, [nsIAccessibleText]);
+  this.offset = aOffset == -1 ? this.target.characterCount : aOffset;
+  this.focus = aFocusTargetID ? getAccessible(aFocusTargetID) : null;
+
+  this.invoke = function setCaretOffset_invoke() {
+    this.target.caretOffset = this.offset;
+  };
+
+  this.getID = function setCaretOffset_getID() {
+    return "Set caretOffset on " + prettyName(aID) + " at " + this.offset;
+  };
+
+  this.eventSeq = [new caretMoveChecker(this.offset, true, this.target)];
+
+  if (this.focus) {
+    this.eventSeq.push(new asyncInvokerChecker(EVENT_FOCUS, this.focus));
+  }
+}
+
+// //////////////////////////////////////////////////////////////////////////////
+// Event queue checkers
+
+/**
+ * Common invoker checker (see eventSeq of eventQueue).
+ */
+function invokerChecker(aEventType, aTargetOrFunc, aTargetFuncArg, aIsAsync) {
+  this.type = aEventType;
+  this.async = aIsAsync;
+
+  this.__defineGetter__("target", invokerChecker_targetGetter);
+  this.__defineSetter__("target", invokerChecker_targetSetter);
+
+  // implementation details
+  function invokerChecker_targetGetter() {
+    if (typeof this.mTarget == "function") {
+      return this.mTarget.call(null, this.mTargetFuncArg);
+    }
+    if (typeof this.mTarget == "string") {
+      return getNode(this.mTarget);
+    }
+
+    return this.mTarget;
+  }
+
+  function invokerChecker_targetSetter(aValue) {
+    this.mTarget = aValue;
+    return this.mTarget;
+  }
+
+  this.__defineGetter__("targetDescr", invokerChecker_targetDescrGetter);
+
+  function invokerChecker_targetDescrGetter() {
+    if (typeof this.mTarget == "function") {
+      return this.mTarget.name + ", arg: " + this.mTargetFuncArg;
+    }
+
+    return prettyName(this.mTarget);
+  }
+
+  this.mTarget = aTargetOrFunc;
+  this.mTargetFuncArg = aTargetFuncArg;
+}
+
+/**
+ * event checker that forces preceeding async events to happen before this
+ * checker.
+ */
+function orderChecker() {
+  // XXX it doesn't actually work to inherit from invokerChecker, but maybe we
+  // should fix that?
+  //  this.__proto__ = new invokerChecker(null, null, null, false);
+}
+
+/**
+ * Generic invoker checker for todo events.
+ */
+function todo_invokerChecker(aEventType, aTargetOrFunc, aTargetFuncArg) {
+  this.__proto__ = new invokerChecker(
+    aEventType,
+    aTargetOrFunc,
+    aTargetFuncArg,
+    true
+  );
+  this.todo = true;
+}
+
+/**
+ * Generic invoker checker for unexpected events.
+ */
+function unexpectedInvokerChecker(aEventType, aTargetOrFunc, aTargetFuncArg) {
+  this.__proto__ = new invokerChecker(
+    aEventType,
+    aTargetOrFunc,
+    aTargetFuncArg,
+    true
+  );
+
+  this.unexpected = true;
+}
+
+/**
+ * Common invoker checker for async events.
+ */
+function asyncInvokerChecker(aEventType, aTargetOrFunc, aTargetFuncArg) {
+  this.__proto__ = new invokerChecker(
+    aEventType,
+    aTargetOrFunc,
+    aTargetFuncArg,
+    true
+  );
+}
+
+function focusChecker(aTargetOrFunc, aTargetFuncArg) {
+  this.__proto__ = new invokerChecker(
+    EVENT_FOCUS,
+    aTargetOrFunc,
+    aTargetFuncArg,
+    false
+  );
+
+  this.unique = true; // focus event must be unique for invoker action
+
+  this.check = function focusChecker_check(aEvent) {
+    testStates(aEvent.accessible, STATE_FOCUSED);
+  };
+}
+
+function nofocusChecker(aID) {
+  this.__proto__ = new focusChecker(aID);
+  this.unexpected = true;
+}
+
+/**
+ * Text inserted/removed events checker.
+ * @param aFromUser  [in, optional] kNotFromUserInput or kFromUserInput
+ */
+function textChangeChecker(
+  aID,
+  aStart,
+  aEnd,
+  aTextOrFunc,
+  aIsInserted,
+  aFromUser,
+  aAsync
+) {
+  this.target = getNode(aID);
+  this.type = aIsInserted ? EVENT_TEXT_INSERTED : EVENT_TEXT_REMOVED;
+  this.startOffset = aStart;
+  this.endOffset = aEnd;
+  this.textOrFunc = aTextOrFunc;
+  this.async = aAsync;
+
+  this.match = function stextChangeChecker_match(aEvent) {
+    if (
+      !(aEvent instanceof nsIAccessibleTextChangeEvent) ||
+      aEvent.accessible !== getAccessible(this.target)
+    ) {
+      return false;
+    }
+
+    let tcEvent = aEvent.QueryInterface(nsIAccessibleTextChangeEvent);
+    let modifiedText =
+      typeof this.textOrFunc === "function"
+        ? this.textOrFunc()
+        : this.textOrFunc;
+    return modifiedText === tcEvent.modifiedText;
+  };
+
+  this.check = function textChangeChecker_check(aEvent) {
+    aEvent.QueryInterface(nsIAccessibleTextChangeEvent);
+
+    var modifiedText =
+      typeof this.textOrFunc == "function"
+        ? this.textOrFunc()
+        : this.textOrFunc;
+    var modifiedTextLen =
+      this.endOffset == -1 ? modifiedText.length : aEnd - aStart;
+
+    is(
+      aEvent.start,
+      this.startOffset,
+      "Wrong start offset for " + prettyName(aID)
+    );
+    is(aEvent.length, modifiedTextLen, "Wrong length for " + prettyName(aID));
+    var changeInfo = aIsInserted ? "inserted" : "removed";
+    is(
+      aEvent.isInserted,
+      aIsInserted,
+      "Text was " + changeInfo + " for " + prettyName(aID)
+    );
+    is(
+      aEvent.modifiedText,
+      modifiedText,
+      "Wrong " + changeInfo + " text for " + prettyName(aID)
+    );
+    if (typeof aFromUser != "undefined") {
+      is(
+        aEvent.isFromUserInput,
+        aFromUser,
+        "wrong value of isFromUserInput() for " + prettyName(aID)
+      );
+    }
+  };
+}
+
+/**
+ * Caret move events checker.
+ */
+function caretMoveChecker(
+  aCaretOffset,
+  aIsSelectionCollapsed,
+  aTargetOrFunc,
+  aTargetFuncArg,
+  aIsAsync
+) {
+  this.__proto__ = new invokerChecker(
+    EVENT_TEXT_CARET_MOVED,
+    aTargetOrFunc,
+    aTargetFuncArg,
+    aIsAsync
+  );
+
+  this.check = function caretMoveChecker_check(aEvent) {
+    let evt = aEvent.QueryInterface(nsIAccessibleCaretMoveEvent);
+    is(
+      evt.caretOffset,
+      aCaretOffset,
+      "Wrong caret offset for " + prettyName(aEvent.accessible)
+    );
+    is(
+      evt.isSelectionCollapsed,
+      aIsSelectionCollapsed,
+      "wrong collapsed value for  " + prettyName(aEvent.accessible)
+    );
+  };
+}
+
+function asyncCaretMoveChecker(aCaretOffset, aTargetOrFunc, aTargetFuncArg) {
+  this.__proto__ = new caretMoveChecker(
+    aCaretOffset,
+    true, // Caret is collapsed
+    aTargetOrFunc,
+    aTargetFuncArg,
+    true
+  );
+}
+
+/**
+ * Text selection change checker.
+ */
+function textSelectionChecker(
+  aID,
+  aStartOffset,
+  aEndOffset,
+  aRangeStartContainer,
+  aRangeStartOffset,
+  aRangeEndContainer,
+  aRangeEndOffset
+) {
+  this.__proto__ = new invokerChecker(EVENT_TEXT_SELECTION_CHANGED, aID);
+
+  this.check = function textSelectionChecker_check(aEvent) {
+    if (aStartOffset == aEndOffset) {
+      ok(true, "Collapsed selection triggered text selection change event.");
+    } else {
+      testTextGetSelection(aID, aStartOffset, aEndOffset, 0);
+
+      // Test selection test range
+      let selectionRanges = aEvent.QueryInterface(
+        nsIAccessibleTextSelectionChangeEvent
+      ).selectionRanges;
+      let range = selectionRanges.queryElementAt(0, nsIAccessibleTextRange);
+      is(
+        range.startContainer,
+        getAccessible(aRangeStartContainer),
+        "correct range start container"
+      );
+      is(range.startOffset, aRangeStartOffset, "correct range start offset");
+      is(range.endOffset, aRangeEndOffset, "correct range end offset");
+      is(
+        range.endContainer,
+        getAccessible(aRangeEndContainer),
+        "correct range end container"
+      );
+    }
+  };
+}
+
+/**
+ * Object attribute changed checker
+ */
+function objAttrChangedChecker(aID, aAttr) {
+  this.__proto__ = new invokerChecker(EVENT_OBJECT_ATTRIBUTE_CHANGED, aID);
+
+  this.check = function objAttrChangedChecker_check(aEvent) {
+    var event = null;
+    try {
+      var event = aEvent.QueryInterface(
+        nsIAccessibleObjectAttributeChangedEvent
+      );
+    } catch (e) {
+      ok(false, "Object attribute changed event was expected");
+    }
+
+    if (!event) {
+      return;
+    }
+
+    is(
+      event.changedAttribute,
+      aAttr,
+      "Wrong attribute name of the object attribute changed event."
+    );
+  };
+
+  this.match = function objAttrChangedChecker_match(aEvent) {
+    if (aEvent instanceof nsIAccessibleObjectAttributeChangedEvent) {
+      var scEvent = aEvent.QueryInterface(
+        nsIAccessibleObjectAttributeChangedEvent
+      );
+      return (
+        aEvent.accessible == getAccessible(this.target) &&
+        scEvent.changedAttribute == aAttr
+      );
+    }
+    return false;
+  };
+}
+
+/**
+ * State change checker.
+ */
+function stateChangeChecker(
+  aState,
+  aIsExtraState,
+  aIsEnabled,
+  aTargetOrFunc,
+  aTargetFuncArg,
+  aIsAsync,
+  aSkipCurrentStateCheck
+) {
+  this.__proto__ = new invokerChecker(
+    EVENT_STATE_CHANGE,
+    aTargetOrFunc,
+    aTargetFuncArg,
+    aIsAsync
+  );
+
+  this.check = function stateChangeChecker_check(aEvent) {
+    var event = null;
+    try {
+      var event = aEvent.QueryInterface(nsIAccessibleStateChangeEvent);
+    } catch (e) {
+      ok(false, "State change event was expected");
+    }
+
+    if (!event) {
+      return;
+    }
+
+    is(
+      event.isExtraState,
+      aIsExtraState,
+      "Wrong extra state bit of the statechange event."
+    );
+    isState(
+      event.state,
+      aState,
+      aIsExtraState,
+      "Wrong state of the statechange event."
+    );
+    is(event.isEnabled, aIsEnabled, "Wrong state of statechange event state");
+
+    if (aSkipCurrentStateCheck) {
+      todo(false, "State checking was skipped!");
+      return;
+    }
+
+    var state = aIsEnabled ? (aIsExtraState ? 0 : aState) : 0;
+    var extraState = aIsEnabled ? (aIsExtraState ? aState : 0) : 0;
+    var unxpdState = aIsEnabled ? 0 : aIsExtraState ? 0 : aState;
+    var unxpdExtraState = aIsEnabled ? 0 : aIsExtraState ? aState : 0;
+    testStates(
+      event.accessible,
+      state,
+      extraState,
+      unxpdState,
+      unxpdExtraState
+    );
+  };
+
+  this.match = function stateChangeChecker_match(aEvent) {
+    if (aEvent instanceof nsIAccessibleStateChangeEvent) {
+      var scEvent = aEvent.QueryInterface(nsIAccessibleStateChangeEvent);
+      return (
+        aEvent.accessible == getAccessible(this.target) &&
+        scEvent.state == aState
+      );
+    }
+    return false;
+  };
+}
+
+function asyncStateChangeChecker(
+  aState,
+  aIsExtraState,
+  aIsEnabled,
+  aTargetOrFunc,
+  aTargetFuncArg
+) {
+  this.__proto__ = new stateChangeChecker(
+    aState,
+    aIsExtraState,
+    aIsEnabled,
+    aTargetOrFunc,
+    aTargetFuncArg,
+    true
+  );
+}
+
+/**
+ * Expanded state change checker.
+ */
+function expandedStateChecker(aIsEnabled, aTargetOrFunc, aTargetFuncArg) {
+  this.__proto__ = new invokerChecker(
+    EVENT_STATE_CHANGE,
+    aTargetOrFunc,
+    aTargetFuncArg
+  );
+
+  this.check = function expandedStateChecker_check(aEvent) {
+    var event = null;
+    try {
+      var event = aEvent.QueryInterface(nsIAccessibleStateChangeEvent);
+    } catch (e) {
+      ok(false, "State change event was expected");
+    }
+
+    if (!event) {
+      return;
+    }
+
+    is(event.state, STATE_EXPANDED, "Wrong state of the statechange event.");
+    is(
+      event.isExtraState,
+      false,
+      "Wrong extra state bit of the statechange event."
+    );
+    is(event.isEnabled, aIsEnabled, "Wrong state of statechange event state");
+
+    testStates(event.accessible, aIsEnabled ? STATE_EXPANDED : STATE_COLLAPSED);
+  };
+}
+
+// //////////////////////////////////////////////////////////////////////////////
+// Event sequances (array of predefined checkers)
+
+/**
+ * Event seq for single selection change.
+ */
+function selChangeSeq(aUnselectedID, aSelectedID) {
+  if (!aUnselectedID) {
+    return [
+      new stateChangeChecker(STATE_SELECTED, false, true, aSelectedID),
+      new invokerChecker(EVENT_SELECTION, aSelectedID),
+    ];
+  }
+
+  // Return two possible scenarios: depending on widget type when selection is
+  // moved the the order of items that get selected and unselected may vary.
+  return [
+    [
+      new stateChangeChecker(STATE_SELECTED, false, false, aUnselectedID),
+      new stateChangeChecker(STATE_SELECTED, false, true, aSelectedID),
+      new invokerChecker(EVENT_SELECTION, aSelectedID),
+    ],
+    [
+      new stateChangeChecker(STATE_SELECTED, false, true, aSelectedID),
+      new stateChangeChecker(STATE_SELECTED, false, false, aUnselectedID),
+      new invokerChecker(EVENT_SELECTION, aSelectedID),
+    ],
+  ];
+}
+
+/**
+ * Event seq for item removed form the selection.
+ */
+function selRemoveSeq(aUnselectedID) {
+  return [
+    new stateChangeChecker(STATE_SELECTED, false, false, aUnselectedID),
+    new invokerChecker(EVENT_SELECTION_REMOVE, aUnselectedID),
+  ];
+}
+
+/**
+ * Event seq for item added to the selection.
+ */
+function selAddSeq(aSelectedID) {
+  return [
+    new stateChangeChecker(STATE_SELECTED, false, true, aSelectedID),
+    new invokerChecker(EVENT_SELECTION_ADD, aSelectedID),
+  ];
+}
+
+// //////////////////////////////////////////////////////////////////////////////
+// Private implementation details.
+// //////////////////////////////////////////////////////////////////////////////
+
+// //////////////////////////////////////////////////////////////////////////////
+// General
+
+var gA11yEventListeners = {};
+var gA11yEventApplicantsCount = 0;
+
+var gA11yEventObserver = {
+  // eslint-disable-next-line complexity
+  observe: function observe(aSubject, aTopic, aData) {
+    if (aTopic != "accessible-event") {
+      return;
+    }
+
+    var event;
+    try {
+      event = aSubject.QueryInterface(nsIAccessibleEvent);
+    } catch (ex) {
+      // After a test is aborted (i.e. timed out by the harness), this exception is soon triggered.
+      // Remove the leftover observer, otherwise it "leaks" to all the following tests.
+      Services.obs.removeObserver(this, "accessible-event");
+      // Forward the exception, with added explanation.
+      throw new Error(
+        "[accessible/events.js, gA11yEventObserver.observe] This is expected " +
+          `if a previous test has been aborted... Initial exception was: [ ${ex} ]`
+      );
+    }
+    var listenersArray = gA11yEventListeners[event.eventType];
+
+    var eventFromDumpArea = false;
+    if (gLogger.isEnabled()) {
+      // debug stuff
+      eventFromDumpArea = true;
+
+      var target = event.DOMNode;
+      var dumpElm = gA11yEventDumpID
+        ? document.getElementById(gA11yEventDumpID)
+        : null;
+
+      if (dumpElm) {
+        var parent = target;
+        while (parent && parent != dumpElm) {
+          parent = parent.parentNode;
+        }
+      }
+
+      if (!dumpElm || parent != dumpElm) {
+        var type = eventTypeToString(event.eventType);
+        var info = "Event type: " + type;
+
+        if (event instanceof nsIAccessibleStateChangeEvent) {
+          var stateStr = statesToString(
+            event.isExtraState ? 0 : event.state,
+            event.isExtraState ? event.state : 0
+          );
+          info += ", state: " + stateStr + ", is enabled: " + event.isEnabled;
+        } else if (event instanceof nsIAccessibleTextChangeEvent) {
+          info +=
+            ", start: " +
+            event.start +
+            ", length: " +
+            event.length +
+            ", " +
+            (event.isInserted ? "inserted" : "removed") +
+            " text: " +
+            event.modifiedText;
+        }
+
+        info += ". Target: " + prettyName(event.accessible);
+
+        if (listenersArray) {
+          info += ". Listeners count: " + listenersArray.length;
+        }
+
+        if (gLogger.hasFeature("parentchain:" + type)) {
+          info += "\nParent chain:\n";
+          var acc = event.accessible;
+          while (acc) {
+            info += "  " + prettyName(acc) + "\n";
+            acc = acc.parent;
+          }
+        }
+
+        eventFromDumpArea = false;
+        gLogger.log(info);
+      }
+    }
+
+    // Do not notify listeners if event is result of event log changes.
+    if (!listenersArray || eventFromDumpArea) {
+      return;
+    }
+
+    for (var index = 0; index < listenersArray.length; index++) {
+      listenersArray[index].handleEvent(event);
+    }
+  },
+};
+
+function listenA11yEvents(aStartToListen) {
+  if (aStartToListen) {
+    // Add observer when adding the first applicant only.
+    if (!gA11yEventApplicantsCount++) {
+      Services.obs.addObserver(gA11yEventObserver, "accessible-event");
+    }
+  } else {
+    // Remove observer when there are no more applicants only.
+    // '< 0' case should not happen, but just in case: removeObserver() will throw.
+    // eslint-disable-next-line no-lonely-if
+    if (--gA11yEventApplicantsCount <= 0) {
+      Services.obs.removeObserver(gA11yEventObserver, "accessible-event");
+    }
+  }
+}
+
+function addA11yEventListener(aEventType, aEventHandler) {
+  if (!(aEventType in gA11yEventListeners)) {
+    gA11yEventListeners[aEventType] = [];
+  }
+
+  var listenersArray = gA11yEventListeners[aEventType];
+  var index = listenersArray.indexOf(aEventHandler);
+  if (index == -1) {
+    listenersArray.push(aEventHandler);
+  }
+}
+
+function removeA11yEventListener(aEventType, aEventHandler) {
+  var listenersArray = gA11yEventListeners[aEventType];
+  if (!listenersArray) {
+    return false;
+  }
+
+  var index = listenersArray.indexOf(aEventHandler);
+  if (index == -1) {
+    return false;
+  }
+
+  listenersArray.splice(index, 1);
+
+  if (!listenersArray.length) {
+    gA11yEventListeners[aEventType] = null;
+    delete gA11yEventListeners[aEventType];
+  }
+
+  return true;
+}
+
+/**
+ * Used to dump debug information.
+ */
+var gLogger = {
+  /**
+   * Return true if dump is enabled.
+   */
+  isEnabled: function debugOutput_isEnabled() {
+    return (
+      gA11yEventDumpID || gA11yEventDumpToConsole || gA11yEventDumpToAppConsole
+    );
+  },
+
+  /**
+   * Dump information into DOM and console if applicable.
+   */
+  log: function logger_log(aMsg) {
+    this.logToConsole(aMsg);
+    this.logToAppConsole(aMsg);
+    this.logToDOM(aMsg);
+  },
+
+  /**
+   * Log message to DOM.
+   *
+   * @param aMsg          [in] the primary message
+   * @param aHasIndent    [in, optional] if specified the message has an indent
+   * @param aPreEmphText  [in, optional] the text is colored and appended prior
+   *                        primary message
+   */
+  logToDOM: function logger_logToDOM(aMsg, aHasIndent, aPreEmphText) {
+    if (gA11yEventDumpID == "") {
+      return;
+    }
+
+    var dumpElm = document.getElementById(gA11yEventDumpID);
+    if (!dumpElm) {
+      ok(
+        false,
+        "No dump element '" + gA11yEventDumpID + "' within the document!"
+      );
+      return;
+    }
+
+    var containerTagName =
+      ChromeUtils.getClassName(document) == "HTMLDocument"
+        ? "div"
+        : "description";
+
+    var container = document.createElement(containerTagName);
+    if (aHasIndent) {
+      container.setAttribute("style", "padding-left: 10px;");
+    }
+
+    if (aPreEmphText) {
+      var inlineTagName =
+        ChromeUtils.getClassName(document) == "HTMLDocument"
+          ? "span"
+          : "description";
+      var emphElm = document.createElement(inlineTagName);
+      emphElm.setAttribute("style", "color: blue;");
+      emphElm.textContent = aPreEmphText;
+
+      container.appendChild(emphElm);
+    }
+
+    var textNode = document.createTextNode(aMsg);
+    container.appendChild(textNode);
+
+    dumpElm.appendChild(container);
+  },
+
+  /**
+   * Log message to console.
+   */
+  logToConsole: function logger_logToConsole(aMsg) {
+    if (gA11yEventDumpToConsole) {
+      dump("\n" + aMsg + "\n");
+    }
+  },
+
+  /**
+   * Log message to error console.
+   */
+  logToAppConsole: function logger_logToAppConsole(aMsg) {
+    if (gA11yEventDumpToAppConsole) {
+      Services.console.logStringMessage("events: " + aMsg);
+    }
+  },
+
+  /**
+   * Return true if logging feature is enabled.
+   */
+  hasFeature: function logger_hasFeature(aFeature) {
+    var startIdx = gA11yEventDumpFeature.indexOf(aFeature);
+    if (startIdx == -1) {
+      return false;
+    }
+
+    var endIdx = startIdx + aFeature.length;
+    return (
+      endIdx == gA11yEventDumpFeature.length ||
+      gA11yEventDumpFeature[endIdx] == ";"
+    );
+  },
+};
+
+// //////////////////////////////////////////////////////////////////////////////
+// Sequence
+
+/**
+ * Base class of sequence item.
+ */
+function sequenceItem(aProcessor, aEventType, aTarget, aItemID) {
+  // private
+
+  this.startProcess = function sequenceItem_startProcess() {
+    this.queue.invoke();
+  };
+
+  this.queue = new eventQueue();
+  this.queue.onFinish = function () {
+    aProcessor.onProcessed();
+    return DO_NOT_FINISH_TEST;
+  };
+
+  var invoker = {
+    invoke: function invoker_invoke() {
+      return aProcessor.process();
+    },
+    getID: function invoker_getID() {
+      return aItemID;
+    },
+    eventSeq: [new invokerChecker(aEventType, aTarget)],
+  };
+
+  this.queue.push(invoker);
+}
+
+// //////////////////////////////////////////////////////////////////////////////
+// Event queue invokers
+
+/**
+ * Invoker base class for prepare an action.
+ */
+function synthAction(aNodeOrID, aEventsObj) {
+  this.DOMNode = getNode(aNodeOrID);
+
+  if (aEventsObj) {
+    var scenarios = null;
+    if (aEventsObj instanceof Array) {
+      if (aEventsObj[0] instanceof Array) {
+        scenarios = aEventsObj;
+      }
+      // scenarios
+      else {
+        scenarios = [aEventsObj];
+      } // event sequance
+    } else {
+      scenarios = [[aEventsObj]]; // a single checker object
+    }
+
+    for (var i = 0; i < scenarios.length; i++) {
+      defineScenario(this, scenarios[i]);
+    }
+  }
+
+  this.getID = function synthAction_getID() {
+    return prettyName(aNodeOrID) + " action";
+  };
+}