Some FocusTracker and TabBar unittests fail in master on OS X with latest Firefox

[telamonian]

I'm using OS X 10.14, and the latest version of Firefox (69). On master, I recently noticed that a few dozen of the unittest for the FocusTracker and TabBar widgets were failing:

SUMMARY:
✔ 760 tests completed
✖ 34 tests failed

FAILED TESTS:
  @phosphor/widgets
    FocusTracker
      #currentChanged
        ✖ should be emitted when the current widget has changed
          Firefox 69.0.0 (Mac OS X 10.14.0)
        expected null to not equal null
        AssertionError@build/bundle.test.js:21511:13
        module.exports/Assertion.prototype.assert@build/bundle.test.js:39332:13
        assertEqual@build/bundle.test.js:39849:12
        module.exports/ctx[name]@build/bundle.test.js:43285:25
        @build/bundle.test.js:31062:48


      #activeChanged
        ✖ should be emitted when the active widget has changed
          Firefox 69.0.0 (Mac OS X 10.14.0)
        expected null to not equal null
        AssertionError@build/bundle.test.js:21511:13
        module.exports/Assertion.prototype.assert@build/bundle.test.js:39332:13
        assertEqual@build/bundle.test.js:39849:12
        module.exports/ctx[name]@build/bundle.test.js:43285:25
        @build/bundle.test.js:31093:48

...

The strange thing is that I don't see these failures when testing using Chrome, and I don't see the failures in the CI run on the commits I made in PR #437, even though the CI also uses Firefox. Not sure what's going on.

The rest of the unittest failure log

    ✖ should be emitted when the active widget is set to null
      Firefox 69.0.0 (Mac OS X 10.14.0)
    expected null to not equal null
    AssertionError@build/bundle.test.js:21511:13
    module.exports/Assertion.prototype.assert@build/bundle.test.js:39332:13
    assertEqual@build/bundle.test.js:39849:12
    module.exports/ctx[name]@build/bundle.test.js:43285:25
    @build/bundle.test.js:31107:48


  #currentWidget
    ✖ should be set to the widget that gained focus
      Firefox 69.0.0 (Mac OS X 10.14.0)
    expected { Object (_flags, _layout, ...) } to equal { Object (_flags, _layout, ...) }
    AssertionError@build/bundle.test.js:21511:13
    module.exports/Assertion.prototype.assert@build/bundle.test.js:39332:13
    assertEqual@build/bundle.test.js:39849:12
    module.exports/ctx[name]@build/bundle.test.js:43285:25
    @build/bundle.test.js:31146:57


    ✖ should revert to the previous widget if the current widget is removed
      Firefox 69.0.0 (Mac OS X 10.14.0)
    expected { Object (_flags, _layout, ...) } to equal { Object (_flags, _layout, ...) }
    AssertionError@build/bundle.test.js:21511:13
    module.exports/Assertion.prototype.assert@build/bundle.test.js:39332:13
    assertEqual@build/bundle.test.js:39849:12
    module.exports/ctx[name]@build/bundle.test.js:43285:25
    @build/bundle.test.js:31156:57


  #activeWidget
    ✖ should be set to `null` when the active widget loses focus
      Firefox 69.0.0 (Mac OS X 10.14.0)
    expected { Object (_flags, _layout, ...) } to equal null
    AssertionError@build/bundle.test.js:21511:13
    module.exports/Assertion.prototype.assert@build/bundle.test.js:39332:13
    assertEqual@build/bundle.test.js:39849:12
    module.exports/ctx[name]@build/bundle.test.js:43285:25
    @build/bundle.test.js:31186:56


    ✖ should be set to the widget that gained focus
      Firefox 69.0.0 (Mac OS X 10.14.0)
    expected { Object (_flags, _layout, ...) } to equal { Object (_flags, _layout, ...) }
    AssertionError@build/bundle.test.js:21511:13
    module.exports/Assertion.prototype.assert@build/bundle.test.js:39332:13
    assertEqual@build/bundle.test.js:39849:12
    module.exports/ctx[name]@build/bundle.test.js:43285:25
    @build/bundle.test.js:31197:56


  #focusNumber()
    ✖ should give the highest number for the currentWidget
      Firefox 69.0.0 (Mac OS X 10.14.0)
    expected -1 to equal 1
    AssertionError@build/bundle.test.js:21511:13
    module.exports/Assertion.prototype.assert@build/bundle.test.js:39332:13
    assertEqual@build/bundle.test.js:39849:12
    module.exports/ctx[name]@build/bundle.test.js:43285:25
    @build/bundle.test.js:31236:64


    ✖ should update when a widget gains focus
      Firefox 69.0.0 (Mac OS X 10.14.0)
    expected 0 to equal 2
    AssertionError@build/bundle.test.js:21511:13
    module.exports/Assertion.prototype.assert@build/bundle.test.js:39332:13
    assertEqual@build/bundle.test.js:39849:12
    module.exports/ctx[name]@build/bundle.test.js:43285:25
    @build/bundle.test.js:31257:64


  #remove()
    ✖ should set the currentWidget to the previous one if the widget is the currentWidget
      Firefox 69.0.0 (Mac OS X 10.14.0)
    expected { Object (_flags, _layout, ...) } to equal { Object (_flags, _layout, ...) }
    AssertionError@build/bundle.test.js:21511:13
    module.exports/Assertion.prototype.assert@build/bundle.test.js:39332:13
    assertEqual@build/bundle.test.js:39849:12
    module.exports/ctx[name]@build/bundle.test.js:43285:25
    @build/bundle.test.js:31318:57


TabBar
  #tabMoved
    ✖ should be emitted when a tab is moved right by the user
      Firefox 69.0.0 (Mac OS X 10.14.0)
    Timeout of 2000ms exceeded. For async tests and hooks, ensure "done()" is called; if returning a Promise, ensure it resolves.

    ✖ should be emitted when a tab is moved left by the user
      Firefox 69.0.0 (Mac OS X 10.14.0)
    Timeout of 2000ms exceeded. For async tests and hooks, ensure "done()" is called; if returning a Promise, ensure it resolves.

  #tabActivateRequested
    ✖ should be emitted when a tab is left pressed by the user
      Firefox 69.0.0 (Mac OS X 10.14.0)
    expected false to equal true
    AssertionError@build/bundle.test.js:21511:13
    module.exports/Assertion.prototype.assert@build/bundle.test.js:39332:13
    assertEqual@build/bundle.test.js:39849:12
    module.exports/ctx[name]@build/bundle.test.js:43285:25
    @build/bundle.test.js:35414:42


    ✖ should make the tab current and emit the `currentChanged` signal
      Firefox 69.0.0 (Mac OS X 10.14.0)
    expected 1 to equal 2
    AssertionError@build/bundle.test.js:21511:13
    module.exports/Assertion.prototype.assert@build/bundle.test.js:39332:13
    assertEqual@build/bundle.test.js:39849:12
    module.exports/ctx[name]@build/bundle.test.js:43285:25
    @build/bundle.test.js:35424:52


    ✖ should emit even if the pressed tab is the current tab
      Firefox 69.0.0 (Mac OS X 10.14.0)
    expected false to equal true
    AssertionError@build/bundle.test.js:21511:13
    module.exports/Assertion.prototype.assert@build/bundle.test.js:39332:13
    assertEqual@build/bundle.test.js:39849:12
    module.exports/ctx[name]@build/bundle.test.js:43285:25
    @build/bundle.test.js:35435:42


  #tabCloseRequested
    ✖ should be emitted when a tab close icon is left clicked
      Firefox 69.0.0 (Mac OS X 10.14.0)
    expected false to equal true
    AssertionError@build/bundle.test.js:21511:13
    module.exports/Assertion.prototype.assert@build/bundle.test.js:39332:13
    assertEqual@build/bundle.test.js:39849:12
    module.exports/ctx[name]@build/bundle.test.js:43285:25
    @build/bundle.test.js:35458:42


    ✖ should be emitted when a tab is middle clicked
      Firefox 69.0.0 (Mac OS X 10.14.0)
    expected false to equal true
    AssertionError@build/bundle.test.js:21511:13
    module.exports/Assertion.prototype.assert@build/bundle.test.js:39332:13
    assertEqual@build/bundle.test.js:39849:12
    module.exports/ctx[name]@build/bundle.test.js:43285:25
    @build/bundle.test.js:35471:42


  #tabDetachRequested
    ✖ should be emitted when a tab is dragged beyond the detach threshold
      Firefox 69.0.0 (Mac OS X 10.14.0)
    expected false to equal true
    AssertionError@build/bundle.test.js:21511:13
    module.exports/Assertion.prototype.assert@build/bundle.test.js:39332:13
    assertEqual@build/bundle.test.js:39849:12
    module.exports/ctx[name]@build/bundle.test.js:43285:25
    @build/bundle.test.js:35512:42


    ✖ should be handled by calling `releaseMouse` and removing the tab
      Firefox 69.0.0 (Mac OS X 10.14.0)
    expected false to equal true
    AssertionError@build/bundle.test.js:21511:13
    module.exports/Assertion.prototype.assert@build/bundle.test.js:39332:13
    assertEqual@build/bundle.test.js:39849:12
    module.exports/ctx[name]@build/bundle.test.js:43285:25
    @build/bundle.test.js:35524:42


    ✖ should only be emitted once per drag cycle
      Firefox 69.0.0 (Mac OS X 10.14.0)
    expected 0 to equal 1
    AssertionError@build/bundle.test.js:21511:13
    module.exports/Assertion.prototype.assert@build/bundle.test.js:39332:13
    assertEqual@build/bundle.test.js:39849:12
    module.exports/ctx[name]@build/bundle.test.js:43285:25
    @build/bundle.test.js:35536:42


    ✖ should add the `p-mod-dragging` class to the tab and the bar
      Firefox 69.0.0 (Mac OS X 10.14.0)
    expected false to equal true
    AssertionError@build/bundle.test.js:21511:13
    module.exports/Assertion.prototype.assert@build/bundle.test.js:39332:13
    assertEqual@build/bundle.test.js:39849:12
    module.exports/ctx[name]@build/bundle.test.js:43285:25
    @build/bundle.test.js:35550:42


  #allowDeselect
    ✖ should determine whether a tab can be deselected by the user
      Firefox 69.0.0 (Mac OS X 10.14.0)
    expected 2 to equal -1
    AssertionError@build/bundle.test.js:21511:13
    module.exports/Assertion.prototype.assert@build/bundle.test.js:39332:13
    assertEqual@build/bundle.test.js:39849:12
    module.exports/ctx[name]@build/bundle.test.js:43285:25
    @build/bundle.test.js:35595:52


  #handleEvent()
    left click
      ✖ should emit a tab close requested signal
        Firefox 69.0.0 (Mac OS X 10.14.0)
      expected false to equal true
      AssertionError@build/bundle.test.js:21511:13
      module.exports/Assertion.prototype.assert@build/bundle.test.js:39332:13
      assertEqual@build/bundle.test.js:39849:12
      module.exports/ctx[name]@build/bundle.test.js:43285:25
      @build/bundle.test.js:35968:46


    middle click
      ✖ should emit a tab close requested signal
        Firefox 69.0.0 (Mac OS X 10.14.0)
      expected false to equal true
      AssertionError@build/bundle.test.js:21511:13
      module.exports/Assertion.prototype.assert@build/bundle.test.js:39332:13
      assertEqual@build/bundle.test.js:39849:12
      module.exports/ctx[name]@build/bundle.test.js:43285:25
      @build/bundle.test.js:36010:46


    mousedown
      ✖ should add event listeners if the tabs are movable
        Firefox 69.0.0 (Mac OS X 10.14.0)
      expected -1 to not equal -1
      AssertionError@build/bundle.test.js:21511:13
      module.exports/Assertion.prototype.assert@build/bundle.test.js:39332:13
      assertEqual@build/bundle.test.js:39849:12
      module.exports/ctx[name]@build/bundle.test.js:43285:25
      @build/bundle.test.js:36044:75


    mousemove
      ✖ should do nothing if there is a drag in progress
        Firefox 69.0.0 (Mac OS X 10.14.0)
      expected 0 to equal 1
      AssertionError@build/bundle.test.js:21511:13
      module.exports/Assertion.prototype.assert@build/bundle.test.js:39332:13
      assertEqual@build/bundle.test.js:39849:12
      module.exports/ctx[name]@build/bundle.test.js:43285:25
      @build/bundle.test.js:36084:46


      ✖ should emit the detach requested signal if the threshold is exceeded
        Firefox 69.0.0 (Mac OS X 10.14.0)
      expected false to equal true
      AssertionError@build/bundle.test.js:21511:13
      module.exports/Assertion.prototype.assert@build/bundle.test.js:39332:13
      assertEqual@build/bundle.test.js:39849:12
      module.exports/ctx[name]@build/bundle.test.js:43285:25
      @build/bundle.test.js:36112:46


      ✖ should bail if the signal handler aborted the drag
        Firefox 69.0.0 (Mac OS X 10.14.0)
      expected false to equal true
      AssertionError@build/bundle.test.js:21511:13
      module.exports/Assertion.prototype.assert@build/bundle.test.js:39332:13
      assertEqual@build/bundle.test.js:39849:12
      module.exports/ctx[name]@build/bundle.test.js:43285:25
      @build/bundle.test.js:36123:46


      ✖ should update the positions of the tabs
        Firefox 69.0.0 (Mac OS X 10.14.0)
      expected false to equal true
      AssertionError@build/bundle.test.js:21511:13
      module.exports/Assertion.prototype.assert@build/bundle.test.js:39332:13
      assertEqual@build/bundle.test.js:39849:12
      module.exports/ctx[name]@build/bundle.test.js:43285:25
      @build/bundle.test.js:36134:46


    mouseup
      ✖ should emit the `tabMoved` signal
        Firefox 69.0.0 (Mac OS X 10.14.0)
      Timeout of 2000ms exceeded. For async tests and hooks, ensure "done()" is called; if returning a Promise, ensure it resolves.

      ✖ should move the tab to its final position
        Firefox 69.0.0 (Mac OS X 10.14.0)
      Timeout of 2000ms exceeded. For async tests and hooks, ensure "done()" is called; if returning a Promise, ensure it resolves.

      ✖ should cancel a middle mouse release
        Firefox 69.0.0 (Mac OS X 10.14.0)
      expected false to equal true
      AssertionError@build/bundle.test.js:21511:13
      module.exports/Assertion.prototype.assert@build/bundle.test.js:39332:13
      assertEqual@build/bundle.test.js:39849:12
      module.exports/ctx[name]@build/bundle.test.js:43285:25
      @build/bundle.test.js:36159:49


    keydown
      ✖ should prevent default
        Firefox 69.0.0 (Mac OS X 10.14.0)
      expected false to equal true
      AssertionError@build/bundle.test.js:21511:13
      module.exports/Assertion.prototype.assert@build/bundle.test.js:39332:13
      assertEqual@build/bundle.test.js:39849:12
      module.exports/ctx[name]@build/bundle.test.js:43285:25
      @build/bundle.test.js:36167:49


    contextmenu
      ✖ should prevent default
        Firefox 69.0.0 (Mac OS X 10.14.0)
      expected false to equal true
      AssertionError@build/bundle.test.js:21511:13
      module.exports/Assertion.prototype.assert@build/bundle.test.js:39332:13
      assertEqual@build/bundle.test.js:39849:12
      module.exports/ctx[name]@build/bundle.test.js:43285:25
      @build/bundle.test.js:36181:49

[sccolbert]

Thanks. Mocking events is hard, and subtle changes by browsers in how they handle offscreen rendering/events/focus can wreak havoc on our unit tests.

If something doesn't work when actually using the browser with a real keyboard and mouse, please let us know.