Add visual regression testing library + tests

[ohltyler]

Description

Adds cypress-image-snapshot testing library into the repo to use for visual regression testing. This is based on jest-image-snapshot. This is particularly useful for charts since there is nothing baked in cypress to do that. In addition, charts rendered with vega are limited in that they are a single element and datapoints can't be examined via html.

The added helper function validateVisSnapshot() can be used by downstream plugins to persist and compare their own snapshots.

Adds tests for the Vis Augmenter feature in both OSD + AD plugin test suites as well.

Issues Resolved

Dashboards PR #4515

Check List

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[ohltyler]

CI fails to run 3.0 cluster, posting local results below (2.9 cluster):
OSD tests:

       Spec                                              Tests  Passing  Failing  Pending  Skipped  
  ┌────────────────────────────────────────────────────────────────────────────────────────────────┐
  │ ✔  core-opensearch-dashboards/opensear      02:13        2        2        -        -        - │
  │    ch-dashboards/apps/vis-augmenter/da                                                         │
  │    shboard_spec.js                                                                             │
  └────────────────────────────────────────────────────────────────────────────────────────────────┘
    ✔  All specs passed!                        02:13        2        2        -        -        -  

AD tests:

       Spec                                              Tests  Passing  Failing  Pending  Skipped  
  ┌────────────────────────────────────────────────────────────────────────────────────────────────┐
  │ ✔  plugins/anomaly-detection-dashboard      05:55        5        5        -        -        - │
  │    s-plugin/vis_augmenter/associate_de                                                         │
  │    tector_spec.js                                                                              │
  └────────────────────────────────────────────────────────────────────────────────────────────────┘
    ✔  All specs passed!                        05:55        5        5        -        -        -  

[SuZhou-Joe]

The cypress version this repo used does not comply with the peerDependencies of cypress-image-snapshot, do we have any other package that we can use?

[ashwin-pc]

I agree with @SuZhou-Joe, the library you picked hasnt been maintained in a while. There are a few other alternative's including one thats forked this to work with the version of Cypress that we are using. That being said, i dont think that just because the peer dependency isnt met that this will not work, as clearly seen by the PR, but in future, should something break, its likely not going to be fixed.

[ashwin-pc]

not related to this PR but you guys have a lot of wait(time in ms) statements all across your tests. This is almost always unnecessary and can save you guys a lot of time in your tests.

[ashwin-pc]

I ran this test without installing the AD plugin on my instance and ran into a size mismatch error. That being said I thinks its probably because i didnt have the plugin installed, but just something to keep an eye out for.

[ohltyler]

It's interesting, I had originally picked that one since it was the most popular open source option I was seeing on Cypress' official page. But I also this forked one that is continuing to maintain it. I will try switching to this library. Thanks for the catch on the old cypress version dependency.

[ohltyler]

@SuZhou-Joe @ashwin-pc looking closer, all tags of the maintained cypress-image-snapshot require cypress to be >10.0.0. I see we have been locked at 9.5.4 since >1 year ago. Is there potential for bumping the cypress version here? I'm unsure what impact or effort there is regarding test environment setup in the release workflows and if this is a problem.

I can also still install with --legacy-peer-deps and sanity test that things work as expected, and if so, lock the version of that library so there is no new unexpected changes. But I don't think that's the best approach.

cc @seraphjiang @peterzhuamazon

[SuZhou-Joe]

From the screenshot of our CI flow detail, the final version we used seems to be v12.17.2, @ashwin-pc @peterzhuamazon do you know the original intension of this part? And I think we may be able to upgrade our cypress version to v12 for further maintenance as 1. we are actually using v12 now and 2. other cypress-plugins only support cypress >= v10.

[kavilla]

@ohltyler I will close this PR as I haven't seen any updates. Please re-open if there was pending changes on the reviewers side or if you made changes. Or if there any follow up questions.