1 files changed, 286 insertions, 0 deletions
diff --git a/devtools/server/tests/unit/test_layout-reflows-observer.js b/devtools/server/tests/unit/test_layout-reflows-observer.js
new file mode 100644
index 000000000..ff6c07b26
--- /dev/null
+++ b/devtools/server/tests/unit/test_layout-reflows-observer.js
@@ -0,0 +1,286 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Test the LayoutChangesObserver
+
+var {
+  getLayoutChangesObserver,
+  releaseLayoutChangesObserver,
+  LayoutChangesObserver
+} = require("devtools/server/actors/reflow");
+
+// Override set/clearTimeout on LayoutChangesObserver to avoid depending on
+// time in this unit test. This means that LayoutChangesObserver.eventLoopTimer
+// will be the timeout callback instead of the timeout itself, so test cases
+// will need to execute it to fake a timeout
+LayoutChangesObserver.prototype._setTimeout = cb => cb;
+LayoutChangesObserver.prototype._clearTimeout = function () {};
+
+// Mock the tabActor since we only really want to test the LayoutChangesObserver
+// and don't want to depend on a window object, nor want to test protocol.js
+function MockTabActor() {
+  this.window = new MockWindow();
+  this.windows = [this.window];
+  this.attached = true;
+}
+
+function MockWindow() {}
+MockWindow.prototype = {
+  QueryInterface: function () {
+    let self = this;
+    return {
+      getInterface: function () {
+        return {
+          QueryInterface: function () {
+            if (!self.docShell) {
+              self.docShell = new MockDocShell();
+            }
+            return self.docShell;
+          }
+        };
+      }
+    };
+  },
+  setTimeout: function (cb) {
+    // Simply return the cb itself so that we can execute it in the test instead
+    // of depending on a real timeout
+    return cb;
+  },
+  clearTimeout: function () {}
+};
+
+function MockDocShell() {
+  this.observer = null;
+}
+MockDocShell.prototype = {
+  addWeakReflowObserver: function (observer) {
+    this.observer = observer;
+  },
+  removeWeakReflowObserver: function () {},
+  get chromeEventHandler() {
+    return {
+      addEventListener: (type, cb) => {
+        if (type === "resize") {
+          this.resizeCb = cb;
+        }
+      },
+      removeEventListener: (type, cb) => {
+        if (type === "resize" && cb === this.resizeCb) {
+          this.resizeCb = null;
+        }
+      }
+    };
+  },
+  mockResize: function () {
+    if (this.resizeCb) {
+      this.resizeCb();
+    }
+  }
+};
+
+function run_test() {
+  instancesOfObserversAreSharedBetweenWindows();
+  eventsAreBatched();
+  noEventsAreSentWhenThereAreNoReflowsAndLoopTimeouts();
+  observerIsAlreadyStarted();
+  destroyStopsObserving();
+  stoppingAndStartingSeveralTimesWorksCorrectly();
+  reflowsArentStackedWhenStopped();
+  stackedReflowsAreResetOnStop();
+}
+
+function instancesOfObserversAreSharedBetweenWindows() {
+  do_print("Checking that when requesting twice an instances of the observer " +
+    "for the same TabActor, the instance is shared");
+
+  do_print("Checking 2 instances of the observer for the tabActor 1");
+  let tabActor1 = new MockTabActor();
+  let obs11 = getLayoutChangesObserver(tabActor1);
+  let obs12 = getLayoutChangesObserver(tabActor1);
+  do_check_eq(obs11, obs12);
+
+  do_print("Checking 2 instances of the observer for the tabActor 2");
+  let tabActor2 = new MockTabActor();
+  let obs21 = getLayoutChangesObserver(tabActor2);
+  let obs22 = getLayoutChangesObserver(tabActor2);
+  do_check_eq(obs21, obs22);
+
+  do_print("Checking that observers instances for 2 different tabActors are " +
+    "different");
+  do_check_neq(obs11, obs21);
+
+  releaseLayoutChangesObserver(tabActor1);
+  releaseLayoutChangesObserver(tabActor1);
+  releaseLayoutChangesObserver(tabActor2);
+  releaseLayoutChangesObserver(tabActor2);
+}
+
+function eventsAreBatched() {
+  do_print("Checking that reflow events are batched and only sent when the " +
+    "timeout expires");
+
+  // Note that in this test, we mock the TabActor and its window property, so we
+  // also mock the setTimeout/clearTimeout mechanism and just call the callback
+  // manually
+  let tabActor = new MockTabActor();
+  let observer = getLayoutChangesObserver(tabActor);
+
+  let reflowsEvents = [];
+  let onReflows = (event, reflows) => reflowsEvents.push(reflows);
+  observer.on("reflows", onReflows);
+
+  let resizeEvents = [];
+  let onResize = () => resizeEvents.push("resize");
+  observer.on("resize", onResize);
+
+  do_print("Fake one reflow event");
+  tabActor.window.docShell.observer.reflow();
+  do_print("Checking that no batched reflow event has been emitted");
+  do_check_eq(reflowsEvents.length, 0);
+
+  do_print("Fake another reflow event");
+  tabActor.window.docShell.observer.reflow();
+  do_print("Checking that still no batched reflow event has been emitted");
+  do_check_eq(reflowsEvents.length, 0);
+
+  do_print("Fake a few of resize events too");
+  tabActor.window.docShell.mockResize();
+  tabActor.window.docShell.mockResize();
+  tabActor.window.docShell.mockResize();
+  do_print("Checking that still no batched resize event has been emitted");
+  do_check_eq(resizeEvents.length, 0);
+
+  do_print("Faking timeout expiration and checking that events are sent");
+  observer.eventLoopTimer();
+  do_check_eq(reflowsEvents.length, 1);
+  do_check_eq(reflowsEvents[0].length, 2);
+  do_check_eq(resizeEvents.length, 1);
+
+  observer.off("reflows", onReflows);
+  observer.off("resize", onResize);
+  releaseLayoutChangesObserver(tabActor);
+}
+
+function noEventsAreSentWhenThereAreNoReflowsAndLoopTimeouts() {
+  do_print("Checking that if no reflows were detected and the event batching " +
+  "loop expires, then no reflows event is sent");
+
+  let tabActor = new MockTabActor();
+  let observer = getLayoutChangesObserver(tabActor);
+
+  let reflowsEvents = [];
+  let onReflows = (event, reflows) => reflowsEvents.push(reflows);
+  observer.on("reflows", onReflows);
+
+  do_print("Faking timeout expiration and checking for reflows");
+  observer.eventLoopTimer();
+  do_check_eq(reflowsEvents.length, 0);
+
+  observer.off("reflows", onReflows);
+  releaseLayoutChangesObserver(tabActor);
+}
+
+function observerIsAlreadyStarted() {
+  do_print("Checking that the observer is already started when getting it");
+
+  let tabActor = new MockTabActor();
+  let observer = getLayoutChangesObserver(tabActor);
+  do_check_true(observer.isObserving);
+
+  observer.stop();
+  do_check_false(observer.isObserving);
+
+  observer.start();
+  do_check_true(observer.isObserving);
+
+  releaseLayoutChangesObserver(tabActor);
+}
+
+function destroyStopsObserving() {
+  do_print("Checking that the destroying the observer stops it");
+
+  let tabActor = new MockTabActor();
+  let observer = getLayoutChangesObserver(tabActor);
+  do_check_true(observer.isObserving);
+
+  observer.destroy();
+  do_check_false(observer.isObserving);
+
+  releaseLayoutChangesObserver(tabActor);
+}
+
+function stoppingAndStartingSeveralTimesWorksCorrectly() {
+  do_print("Checking that the stopping and starting several times the observer" +
+    " works correctly");
+
+  let tabActor = new MockTabActor();
+  let observer = getLayoutChangesObserver(tabActor);
+
+  do_check_true(observer.isObserving);
+  observer.start();
+  observer.start();
+  observer.start();
+  do_check_true(observer.isObserving);
+
+  observer.stop();
+  do_check_false(observer.isObserving);
+
+  observer.stop();
+  observer.stop();
+  do_check_false(observer.isObserving);
+
+  releaseLayoutChangesObserver(tabActor);
+}
+
+function reflowsArentStackedWhenStopped() {
+  do_print("Checking that when stopped, reflows aren't stacked in the observer");
+
+  let tabActor = new MockTabActor();
+  let observer = getLayoutChangesObserver(tabActor);
+
+  do_print("Stoping the observer");
+  observer.stop();
+
+  do_print("Faking reflows");
+  tabActor.window.docShell.observer.reflow();
+  tabActor.window.docShell.observer.reflow();
+  tabActor.window.docShell.observer.reflow();
+
+  do_print("Checking that reflows aren't recorded");
+  do_check_eq(observer.reflows.length, 0);
+
+  do_print("Starting the observer and faking more reflows");
+  observer.start();
+  tabActor.window.docShell.observer.reflow();
+  tabActor.window.docShell.observer.reflow();
+  tabActor.window.docShell.observer.reflow();
+
+  do_print("Checking that reflows are recorded");
+  do_check_eq(observer.reflows.length, 3);
+
+  releaseLayoutChangesObserver(tabActor);
+}
+
+function stackedReflowsAreResetOnStop() {
+  do_print("Checking that stacked reflows are reset on stop");
+
+  let tabActor = new MockTabActor();
+  let observer = getLayoutChangesObserver(tabActor);
+
+  tabActor.window.docShell.observer.reflow();
+  do_check_eq(observer.reflows.length, 1);
+
+  observer.stop();
+  do_check_eq(observer.reflows.length, 0);
+
+  tabActor.window.docShell.observer.reflow();
+  do_check_eq(observer.reflows.length, 0);
+
+  observer.start();
+  do_check_eq(observer.reflows.length, 0);
+
+  tabActor.window.docShell.observer.reflow();
+  do_check_eq(observer.reflows.length, 1);
+
+  releaseLayoutChangesObserver(tabActor);
+}