test: add End-2-End test suite

[yannickcr]

Summary

To improve InstantSearch releases reliability we plan to add some End-2-End tests in addition to our existing unit test suite.

Based on #4030, this PR integrates this test suite to InstantSearch.js.

This PR makes the following changes:

• Add algolia/instantsearch-e2-tests as devDependency (since I'm not sure we want to publish it on npm I link to the GitHub repository).
• Add algolia/instantsearch-e2-tests peerDependencies.
• Add 2 WebdriverIO configurations: one to run tests locally and one to run them on Sauce Labs.
• Add .env file to .gitignore so you can use it to store Sauce Labs credentials (see https://github.com/algolia/instantsearch-e2e-tests#credentials ).
• Add npm scripts to run End-2-End tests:
  • test:e2e: Alias for test:e2e:local.
  • test:e2e:local: Run the test suite on Chrome browser on your local machine.
  • test:e2e:saucelabs: Run the test suite on multiple browsers on the Sauce Labs service.
• Update CircleCI configuration to run the new test_e2e task.
• Update examples to use cp instead of rsync (which is unavailable on CircleCI).

[Haroenv]

• looks like storybook is built for e2e, doesn't seem necessary.
• logs contain "RUNNING", which likely isn't useful on CI?
• looks like we're only testing on windows? I guess fine for now

[yannickcr]

looks like storybook is built for e2e, doesn't seem necessary.

I used the website:build script that also build storybook for Netlify deployment. I can update this to only build storybook for Netlify.

logs contain "RUNNING", which likely isn't useful on CI?

It depends, since the tests can be long to run it can be good to see when they started in the logs. Also there is no option to suppress this in WebdriverIO (still displayed even with logLevel set to silent)

looks like we're only testing on windows? I guess fine for now

No objections to test on multiple platforms but multiplying the browser/platform combinations can seriously lengthen test time so we should choose carefully what to test.

Right now one test take ~30sec, and we can run 5 tests in parallel on SauceLabs

// x = number of tests
// y = number of browser/platform combinations
// the result is the number of minutes to run the e2e test suite
Math.ceil((x * y) / 5) * 0.5

[francoischalifour]

Netlify deployment is not triggered but from the configuration, it should work.

[francoischalifour]

looks like we're only testing on windows? I guess fine for now

I think that's the best minimal effort that we can do now because we use both macOS and Linux on the team, but not Windows. If it doesn't add too much overhead, we can add other platforms.

[rarkins]

@Haroenv yes, Renovate will update this type of reference. Example: renovate-tests/npm8#2

[yannickcr]

Great! Thank you @rarkins 👍

[tkrugg]

could theses be subdependencies of instantsearch-e2e-tests#v1.1.0 ?

[yannickcr]

They could be, but I choose to put them as peerDependencies since the wdio command will be run from instantsearch.js. Also it gives us more control having them as top dependencies.