[Bug] Test hangs for additional ~4s if assertion fails

[skyiea]

In case if screenshots match my test ends in 3s.
If they don't match - in 7s.

For some reason test hangs for additional 4 seconds, even though the actual assertion failure occurs earlier.

[anescobar1991]

That is happening because the diff image creation is very slow within the Jest environment. The diff image is only created for failing tests and said creation is slow because calls to ‘Math’ are orders of magnitude slower in Jest environment than outside of it in node.

Original issue in Jest tracking it is jestjs/jest#4972

I apologize I’ve been unable to do any work outside of responding to issues in last few weeks but I have not had access to a computer for more than an hour a day. I will definitely look into this (and some of the other issues you have brought up) when I get back into the office late next week.

[chrbala]

Would it be possible to do a side-by-side diff instead? The old image diff generator was much faster iirc, because it didn't generate as substantial of a diff.

It would be nice to be able to disable the complete diff - most of the time I don't need to see an overlay diff.

[skyiea]

@chrbala Here is the issue to track: #37
+1 for the idea to optionally disable diff generation in favor of before-and-after image

[anescobar1991]

@chrbala can you open separate issue for the side to side comparison only mode? Then I will discuss with my team tomorrow.

[anescobar1991]

I am working on the PR that should take care of these perf issues. Should be opening it in next few days.

[skyiea]

Just now noticed that I accidentally closed it. Reopened.

[anescobar1991]

This should be solved in 2.3.0 with #40