[test] Add tests for DataGrid filtering feature

[dtassone]

No description provided.

[oliviertassinari]

Nothing works! It works in storybook though

In this case, I would encourage we take it more slowly. We can do the test refactoring and the new test in two different PRs.

[dtassone]

Still WIP but you can have a quick look.
The testUtils abstraction is not rerendering components changed with ApiRef so using testingLibrary which works as expected.

[oliviertassinari]

Please move the refactoring of the tests to a different PR. We are changing tests and source at the same time, we should be able to see what impacts what

[oliviertassinari]

I have opened #723 to improve the first refactoring, as I have seen the same issues. It looks like I should have been more careful in the initial review, and not surface it. An example of why smaller PRs are always better :).

Then, we can rebase this pull request and improve on top of #723.

[dtassone]

Regression: https://deploy-preview-715--material-ui-x.netlify.app/storybook/?path=/story/x-grid-tests-filter--commodity-with-new-rows-via-api

[dtassone]

Regression: https://deploy-preview-715--material-ui-x.netlify.app/storybook/?path=/story/x-grid-tests-filter--commodity-with-new-rows-via-api

Fixed

[oliviertassinari]

Great, we go from 30 tests (2.5s) to 53 tests (4s). The tests run fast enough. We should be able to add x10 more without having to change anything in the infrastructure. I only hope that it won't get slower as we add more features in the data grid.