ResizeObserver pt6: integration

third_party/WebKit/LayoutTests/resize-observer/resources/resizeTestHelper.js

+'use strict';
+
+/**
+  ResizeTestHelper is a framework to test ResizeObserver
+  notifications. Use it to make assertions about ResizeObserverEntries.
+  This framework is needed because ResizeObservations are
+  delivered asynchronously inside the event loop.
+
+  Features:
+  - can queue multiple notification steps in a test
+  - handles timeouts
+  - returns Promise that is fullfilled when test completes.
+    Use to chain tests (since parallel async ResizeObserver tests
+    would conflict if reusing same DOM elements).
+
+  Usage:
+
+  create ResizeTestHelper for every test.
+  Make assertions inside notify, timeout callbacks.
+  Start tests with helper.start()
+  Chain tests with Promises.
+  Counts animation frames, see startCountingRaf
+*/
+
+/*
+  @param name: test name
+  @param steps:
+  {
+    setup: function(ResizeObserver) {
+      // called at the beginning of the test step
+      // your observe/resize code goes here
+    },
+    notify: function(entries, observer) {
+      // ResizeObserver callback.
+      // Make assertions here.
+      // Return true if next step should start on the next event loop.
+    },
+    timeout: function() {
+      // Define this if your test expects to time out.
+      // If undefined, timeout is assert_unreached.
+    }
+  }
+*/
+function ResizeTestHelper(name, steps)
+{
+    this._name = name;
+    this._steps = steps || [];
+    this._stepIdx = -1;
+    this._harnessTest = null;
+    this._observer = new ResizeObserver(this._handleNotification.bind(this));
+    this._timeoutBind = this._handleTimeout.bind(this);
+    this._nextStepBind = this._nextStep.bind(this);
+}
+
+ResizeTestHelper.TIMEOUT = 100;
+
+ResizeTestHelper.prototype = {
+  get _currentStep() {
+    return this._steps[this._stepIdx];
+  },
+
+  _nextStep: function() {
+    if (++this._stepIdx == this._steps.length)
+      return this._done();
+    this._timeoutId = this._harnessTest.step_timeout(
+      this._timeoutBind, ResizeTestHelper.TIMEOUT);
+    try {
+      this._steps[this._stepIdx].setup(this._observer);
+    }
+    catch(err) {
+      console.error(err);
+      this._harnessTest.step(() => {
+        assert_unreached("Caught a throw, possible syntax error");
+      });
+    }
+  },
+
+  _handleNotification: function(entries) {
+    if (this._timeoutId) {
+      window.clearTimeout(this._timeoutId);
+      delete this._timeoutId;
+    }
+    this._harnessTest.step(() => {
+      let rafDelay = this._currentStep.notify(entries, this._observer);
+      if (rafDelay)
+        window.requestAnimationFrame(this._nextStepBind);
+      else
+        this._nextStep();
+    });
+  },
+
+  _handleTimeout: function() {
+    delete this._timeoutId;
+    this._harnessTest.step(() => {
+      if (this._currentStep.timeout) {
+        this._currentStep.timeout();
+      }
+      else {
+        assert_unreached("Timed out waiting for notification. (" + ResizeTestHelper.TIMEOUT + "ms)");
+      }
+      this._nextStep();
+    });
+  },
+
+  _done: function() {
+    this._observer.disconnect();
+    delete this._observer;
+    this._harnessTest.done();
+    if (this._rafCountRequest) {
+      window.cancelAnimationFrame(this._rafCountRequest);
+      delete this._rafCountRequest;
+    }
+    window.requestAnimationFrame(() => { this._resolvePromise(); });
+  },
+
+  start: function() {
+    this._harnessTest = async_test(this._name);
+    this._harnessTest.step(() => {
+      assert_equals(this._stepIdx, -1, "start can only be called once");
+      this._nextStep();
+    });
+    return new Promise( (resolve, reject) => {
+      this._resolvePromise = resolve;
+      this._rejectPromise = reject;
+    });
+  },
+
+  get rafCount() {
+    if (!this._rafCountRequest)
+      throw "rAF count is not active";
+    return this._rafCount;
+  },
+
+  _incrementRaf: function() {
+    if (this._rafCountRequest) {
+      this._rafCount++;
+      this._rafCountRequest = window.requestAnimationFrame(this._incrementRafBind);
+    }
+  },
+
+  startCountingRaf: function() {
+    if (this._rafCountRequest)
+      window.cancelAnimationFrame(this._rafCountRequest);
+    if (!this._incrementRafBind)
+      this._incrementRafBind = this._incrementRaf.bind(this);
+    this._rafCount = 0;
+    this._rafCountRequest = window.requestAnimationFrame(this._incrementRafBind);
+  }
+}