testStartDrag_MouseMove() {
    const dragger = new Dragger(target);

    const e = new StrictMock(BrowserEvent);
    /**
     * @suppress {strictMissingProperties} suppression added to enable type
     * checking
     */
    e.type = EventType.MOUSEMOVE;
    /**
     * @suppress {strictMissingProperties} suppression added to enable type
     * checking
     */
    e.clientX = 1;
    /**
     * @suppress {strictMissingProperties} suppression added to enable type
     * checking
     */
    e.clientY = 2;
    // preventDefault is not called.
    e.$replay();

    let startDragFired = false;
    events.listen(dragger, Dragger.EventType.START, (e) => {
      startDragFired = true;
    });

    dragger.startDrag(e);

    assertTrue('Dragging should be in progress.', dragger.isDragging());
    assertTrue('Start drag event should have fired.', startDragFired);
    assertTrue(
        'Dragger must have registered mousemove handlers.',
        events.hasListener(
            dragger.document_, EventType.MOUSEMOVE, !HAS_SET_CAPTURE));
    assertTrue(
        'Dragger must have registered mouseup handlers.',
        events.hasListener(
            dragger.document_, EventType.MOUSEUP, !HAS_SET_CAPTURE));
    e.$verify();
  }
Tests that start drag happens on other event type than MOUSEDOWN.
     @suppress {checkTypes,visibility} suppression added to enable type checking