Mocha, nodejs promise test can't finish because lack of done

Question

I'm trying to run the test of a promise, but the test fails arguing it exceeded timeout limit, and suggests to make sure I have the done clauses.

This is part of my test code:

$configurations
    .updateConfiguration(configurations_driver.NOT_VALID_MODEL) //invalid model
    .then(function () {
        done(new Error("Expected INVALID_MODEL error but got OK"));
    }, function (error) {
        chai.assert.isNotNull(error);
        chai.expect(error.message).to.be.eq("INVALID_MODEL_ERROR");
        chai.expect(error.kind).to.be.eq("ERROR_KIND");
        chai.expect(error.path).to.be.eq("ERROR_PATH");
        done();
    })
    .catch(done);
});  

I have all the done clauses in there as you can see, so I don't know if I'm missing something in the test or the structure is just wrong.

Answer 1

Mocha supports testing promises without using done as long as you return the promise.

const expect = chai.expect

it('should error', function(){
  return $configurations
    .updateConfiguration(configurations_driver.NOT_VALID_MODEL) //invalid model
    .then(()=> { throw new Error("Expected INVALID_MODEL error but got OK")})
    .catch(error => {
      expect(error).to.not.be.null;
      expect(error.message).to.equal("INVALID_MODEL_ERROR");
      expect(error.kind).to.equal("ERROR_KIND");
      expect(error.path).to.equal("ERROR_PATH");
    })
})

Also look at chai-as-promised to make promise testing more like standard chai assertions/expectations.

chai.should()
chai.use(require('chai-as-promised'))

it('should error', function(){
  return $configurations
    .updateConfiguration(configurations_driver.NOT_VALID_MODEL)
    .should.be.rejectedWith(/INVALID_MODEL_ERROR/)
})

On Node 7.6+ environments or where you have babel / babel-register you can also make use of the async / await promise handlers

it('should error', async function(){
  try {
    await $configurations.updateConfiguration(configurations_driver.NOT_VALID_MODEL)
    throw new Error("Expected INVALID_MODEL error but got OK")})
  } catch (error) {
    expect(error).to.not.be.null;
    expect(error.message).to.equal("INVALID_MODEL_ERROR");
    expect(error.kind).to.equal("ERROR_KIND");
    expect(error.path).to.equal("ERROR_PATH");
  }
})