[Docs]: Better explain to contributors how they can execute a test suite

[ericmorand]

Page(s)

CONTRIBUTING.md

Description

I am currently in the process of trying to add One Double Zero - that restores istanbul accuracy and correctness while using V8 coverage data - as an additional coverage provider for Jest, and for that I've been reading the CONTRIBUTING.md document, at least to understand how I can add some tests for the new provider.

This document says:

It is possible to run the integration test itself manually to inspect that the new behaviour is indeed correct. Here is a small code snippet of how to do just that. This is useful when debugging a failing test.

$ cd e2e/clear-cache
$ node ../../packages/jest-cli/bin/jest.js # It is possible to use `node --inspect`
PASS  __tests__/clear_cache.test.js
✓ stub (3ms)

Test Suites: 1 passed, 1 total
Tests:       1 passed, 1 total
Snapshots:   0 total
Time:        0.232 s, estimated 1 s
Ran all test suites.

Unfortunately, doing what the document explains within the e2e/coverage-provider-v8 directory doesn't work - no test is executed.

Moving deeper, into e2e/coverage-provider-v8/cjs-native-without-sourcemap, the command executes a dummy test that actually checks nothing.

And the following fails:

~/Projects/jest/e2e/__tests__$ node ../../packages/jest-cli/bin/jest.js coverageProviderV8.test.ts

SyntaxError: Cannot use import statement outside a module

It seems like the documentation is either wrong or incomplete.