chore: fix a bug in flaky move test

[maribethb]

Fixes #719 hopefully?

There was a bug in this test, it both opened the context menu and pressed 'm' to start move mode. But that wasn't enough to fix the flaky test.

I changed some of the assertions to be more specific. using chai.assert.isNull gives a better error message than chai.assert as chai knows more about what you're intending to check. the old error didn't tell you what the value was, which could help with debugging. the new message will say something like "expected null, got 123". That did give better error messages but still didn't fix anything (it wasn't supposed to)

Next I tried adding an assertion to make sure the problem wasn't with the context menu showing up. I added a check to make sure that the "Move" option was found, and that assertion never failed. Yet, the test flaked on.

I tried adding some pause time and still flaky, so removed it again.

I tried triggering the move with the 'm' key instead of the context menu and it was still flaky, so I reverted those commits.

Finally I added a "wait for exist" on the move icon, so that the test doesn't continue until move mode is actually activated. This required adding a class to the actual source code. All other changes are to the test code only.

At this point I don't know if it will solve the flaky test but even if it doesn't I think it's worth merging at this point as it does improve the tests.

[maribethb]

FWIW I've been rerunning the tests and the latest failure was a different flaky test, not this one :)

[cpcallen]

Good catch on the unwanted m—and thanks for educating me about the existence of these various fancy assertions. This is definitely an improvement.

[cpcallen]

If bubble isn't used again then why save it? (Unless line length?)

Suggested change

	const bubble = this.browser.$('.blocklyMoveIndicatorBubble');
	await bubble.waitForExist();
	this.browser.$('.blocklyMoveIndicatorBubble').waitForExist();

[maribethb]

Good point, I had remembered running into issues with doing this previously but it was when I needed to assert something about bubble which I'm not doing in this case. Fixed (had to add await so didn't commit your suggestion but fixed it locally and pushed)

[BenHenning]

Apologies for the delay--thanks for reviewing this @cpcallen!