Improve chai support (with detailed output, to match jest exceptions)

[rpgeeganage]

Summary

This PR is an initial attempt to solve #8152.

Test plan

No tests were added yet since this only for review.

Before the change Chai output was as follows.

 FAIL  ./chai.spec.js
  a chai test
    ✕ tests something (4ms)

  ● a chai test › tests something

    AssertionError: expected 'hello world' to equal 'hello sunshine'

      3 | describe('a chai test', () => {
      4 |   it('tests something', () => {
    > 5 |     chai.expect('hello world').to.equal('hello sunshine');
        |                                   ^
      6 |   });
      7 | });

      at Object.equal (chai.spec.js:5:35)

Test Suites: 1 failed, 1 total
Tests:       1 failed, 1 total
Snapshots:   0 total
Time:        1.361s
Ran all test suites matching /chai.spec.js/i.

With modification:

  FAIL  ./chai.spec.js
  a chai test
    ✕ tests something (8ms)

  ● a chai test › tests something

    assert.(received, expected)

    Expected value   "hello sunshine"
    Received:
      "hello world"

    Message:
      expected 'hello world' to equal 'hello sunshine'

    Difference:

    - Expected
    + Received

    - hello sunshine
    + hello world

      3 | describe('a chai test', () => {
      4 |   it('tests something', () => {
    > 5 |     chai.expect('hello world').to.equal('hello sunshine');
        |                                   ^
      6 |   });
      7 | });

      at Object.equal (chai.spec.js:5:35)

Test Suites: 1 failed, 1 total
Tests:       1 failed, 1 total
Snapshots:   0 total
Time:        1.534s
Ran all test suites matching /chai.spec.js/i.

[thymikee]

Nice! Can you add a test to make sure we don't regress? And a changelog entry. Also, how about porting this fix to jest-circus?

[jeysal]

Hey @rpgeeganage, thanks a lot for tackling this!
To expand a bit on @thymikee's circus comment:
jest-circus is a replacement for the old jest-jasmine2, and it is to become the default soon. This is why I agree that we'll need this in circus as well so we don't lose the functionality when changing the default. You can set JEST_CIRCUS=1 in the environment to switch to circus manually. If you need any help with circus or the tests, feel free to ask us! :)

[rpgeeganage]

@thymikee , @jeysal ,
Sorry for the late reply. Thanks a lot for the feedback.
I'll look into the jest-circus. I was not confident enough about the solution and that's why I opened the PR for review.
I'll add tests and look into the jest-circus.
Thanks again.

[rpgeeganage]

@jeysal @thymikee
I have introduced the same fix for circus.
I have check the output as follows.

JEST_CIRCUS=1 node ../../jest_unit/jest/packages/jest-cli/bin/jest.js chai.spec.js
 FAIL  ./chai.spec.js
  a chai test
    ✕ tests something (4ms)

  ● a chai test › tests something

    assert.(received, expected)

    Expected value   "hello sunshine"
    Received:
      "hello world"

    Message:
      expected 'hello world' to equal 'hello sunshine'

    Difference:

    - Expected
    + Received

    - hello sunshine
    + hello world

      3 | describe('a chai test', () => {
      4 |   it('tests something', () => {
    > 5 |     chai.expect('hello world').to.equal('hello sunshine');
        |                                   ^
      6 |   });
      7 | });

      at Object.equal (chai.spec.js:5:35)

Test Suites: 1 failed, 1 total
Tests:       1 failed, 1 total
Snapshots:   0 total
Time:        1.389s
Ran all test suites matching /chai.spec.js/i.

Can you give me a hint on adding tests for these changes? (where or how to add the tests)
Thanks a lot.

[thymikee]

I think the easiest would be to add e2e tests that run whole jest on a specified set of files. They sit in e2e directory, just try to mimic existing ones :)

[rpgeeganage]

@thymikee ,
Thanks a lot. I'll add a new test there.

[rpgeeganage]

@thymikee ,
I have added the tests.
Now still, CI is failing. The failure output is as follows.

$ yarn jest-coverage --color -i --config jest.config.ci.js && yarn test-leak && node scripts/mapCoverage.js && codecov
$ yarn jest --coverage --color -i --config jest.config.ci.js
$ node ./packages/jest-cli/bin/jest.js --coverage --color -i --config jest.config.ci.js
........(node:291) MaxListenersExceededWarning: Possible EventEmitter memory leak detected. 11 exit listeners added. Use emitter.setMaxListeners() to increase limit
.................................................Too long with no output (exceeded 10m0s)

I can't figure out why.

[rpgeeganage]

closing this pr, because I screwed it up. will open a new PR. sorry about that.

[rpgeeganage]

#8454

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