Testing: Upgrade React and Enzyme to the latest version

[gziolo]

Description

Another attempt to upgrade React and Enzyme to the latest version. We started exploration in #2813 and this PR should finally make it happen. All tests work as expected.

As part of this diff I also improved the behavior of throwing an error when test executes console.error. I provided new logic which uses spies and expect call to validate if test should fail. New output looks as follow:

● InserterMenu › should disable already used blocks with usedOnce

expect(jest.fn()).not.toHaveBeenCalled()

Expected mock function not to be called but it was called with:
  ["Warning: Expected `onMouseLeave` listener to be a function, instead got a value of `boolean` type.
    in button (created by InserterMenu)
    in div (created by InserterMenu)
    in div (created by InserterMenu)
    in div (created by InserterMenu)
    in div (created by InserterMenu)
    in InserterMenu (created by WrapperComponent)
    in WrapperComponent"], ["Warning: Expected `onMouseEnter` listener to be a function, instead got a value of `boolean` type.
    in button (created by InserterMenu)
    in div (created by InserterMenu)
    in div (created by InserterMenu)
    in div (created by InserterMenu)
    in div (created by InserterMenu)
    in InserterMenu (created by WrapperComponent)
    in WrapperComponent"]
  
  at Object.<anonymous> (test/setup-test-framework.js:23:23)
  at process._tickCallback (internal/process/next_tick.js:109:7)

It's much easier to read and it properly outputs all warnings and errors.

There are still 2 skipped tests. I will take a closer look at them later and decide if we can fix them or they should be removed.

How Has This Been Tested?

Travis should be happy.

Run npm test locally.

To test new behavior around console.error and console.warn simply put such call in one of the tests.

Checklist:

• My code is tested.
• My code follows the WordPress code style.
• My code follows has proper inline documentation.

[gziolo]

I will look into it later. I added this eslint rule to hide warning.

[gziolo]

This change fixes warnings in the InserterMenu component:

Warning: Expected onMouseLeave listener to be a function, instead got a value of boolean type.
Warning: Expected onMouseEnter listener to be a function, instead got a value of boolean type.

[youknowriad]

❤️

[youknowriad]

🎉

[youknowriad]

you did it 👍

[aduth]

Noting that many of our dependencies define a React peer in the 15.x line, so warnings are logged when installing a new version of a package:

npm WARN [email protected] requires a peer of react@^0.14.0 || ^15.0.0 but none is installed. You must install peer dependencies yourself.
npm WARN [email protected] requires a peer of react-dom@^0.14.0 || ^15.0.0 but none is installed. You must install peer dependencies yourself.
npm WARN [email protected] requires a peer of react@^0.14.0 || ^15.0.0 but none is installed. You must install peer dependencies yourself.
npm WARN [email protected] requires a peer of react-dom@^0.14.0 || ^15.0.0 but none is installed. You must install peer dependencies yourself.
npm WARN [email protected] requires a peer of react@^15.5.8 but none is installed. You must install peer dependencies yourself.
npm WARN [email protected] requires a peer of react@^15.0.0 but none is installed. You must install peer dependencies yourself.
npm WARN [email protected] requires a peer of react-dom@^15.0.0 but none is installed. You must install peer dependencies yourself.

I imagine at least some of these should have updated versions available which define React 16 as a valid peer.

[gziolo]

Yes, we can upgrade them after release v1.5. We are using the latest React and React DOM for some time with the bundled code so it seemed like an easier migration path. I can open a follow-up PR on Monday. Thanks for catching this. @youknowriad left a note about this in the preceding PR but I forget to copy it.