multiple calls to done() doesn't always fail if second done is called async

[boneskull]

Example:

it('should fail', function (done) {
  process.nextTick(function () {
    done();
    setTimeout(done);
  });
});

The above won't fail with a nonzero exit code. EVENT_TEST_FAIL is emitted, but nothing is listening at this point.

To address this:

1. The Runner must have a notion of a "stopped" state
2. If a test fails while the Runner is in the stopped state, then it must throw an exception.
3. How this exception is handled depends on whether the standard uncaught exception handler is still bound. If it is, we let it be handled, and we get a proper stack trace back to the test.
4. If the standard uncaught exception handled has been disabled (which happens when EVENT_RUN_END is emitted)--and the process will fail with a bog-standard uncaught exception--Mocha will need to retain extra information in the error so the user can find which test is responsible. I'm not sure why we lose the stack trace back to the test; maybe somebody can help.

Anyway, I have a fix in-progress for this.

Ref: https://twitter.com/jsumners79/status/1216391159699988481

[iqianxing]

async test throw an uncaught error when test is timeout.
my test code like below:

var assert = require('chai').assert;
describe("# async test", function () {
  this.timeout(2000);

  it("async error", function (done) {
    var errorMessage = "some error"
    setTimeout(function () {
      assert.notOk(errorMessage)
      done();
    }, 5000)
  })
})

i run my test , an uncaught error display on my console like below:

error detail:

mocha\lib\runner.js:962
    throw err;

[iqianxing]

async test throw an uncaught error when test is timeout.
my test code like below:

var assert = require('chai').assert;
describe("# async test", function () {
  this.timeout(2000);

  it("async error", function (done) {
    var errorMessage = "some error"
    setTimeout(function () {
      assert.notOk(errorMessage)
      done();
    }, 5000)
  })
})

i run my test , an uncaught error display on my console like below:

error detail:

mocha\lib\runner.js:962
    throw err;

some async code is still running after async test task is stopped.