Fix intermittently failing unit test

[dsparacio]

There are two test that stay pending and one that intermittently fails.

FragmentModel
- should not be postponed after creation
✓ should not have any loading, executed, canceled or failed requests
when a request has been added
✓ should fire streamCompleted event for a complete request
when a request has been passed for executing
✓[90m should fire loadingStarted event a request
- should remove the request from pending requests
✓ should add the request to loading requests
✓ should be able to abort loading requests
31 passing (1s)
2 pending
1 failing

1. TimelineConverter when the live edge is found should calculate availability window for dynamic mpd:
   AssertionError: expected 0.0009999999999976694 to equal 0
   • expected - actual
     -0.0009999999999976694
     +0

[boushley]

That looks like a float issue, this could be a pain.

[dsparacio]

Yeah i think so. Never happened before in 1.x code so need to investigate this one.

[yturtle98]

The unit test fails when the current time value of "new Date()" in
representation.adaptation.period.mpd.availabilityStartTime = new Date(new Date().getTime() - representation.adaptation.period.mpd.timeShiftBufferDepth * 1000);
of test/dash.TimeLineConverterSpec.js (line 95) is not same as
"new Date()" in
now = calcPresentationTimeFromWallTime(new Date(), representation.adaptation.period);
of src/dash/TimeLineConverter.js (line 156)

To make the value of the start time of the segmentAvailabilityRange be 0 as in dash.TimeLineConverterSpec.js, some time buffer needs to be added to set the availiabilityStartTime, like following:
// 1000ms time buffer is added
representation.adaptation.period.mpd.availabilityStartTime = new Date(new Date().getTime() + 1000 - representation.adaptation.period.mpd.timeShiftBufferDepth * 1000);

[davemevans]

I think using sinon.useFakeTimers in the test setup is the right way to solve this as it stubs Date. This is already used in FragmentModelSpec tests.

The two pending tests are never run (the test specs have been changed to it.skip) since they are no longer meaningful in 2.0. They should be removed.