How to get Mocha to fail a test

Question

I have the following test:

it.only(\'validation should fail\', function(done) {
    var body = {
        title: \"dffdasfsdfsdafddfsadsa\",
        description:          


        

Answer 1

You can call assert.fail:

it("should return empty set of tags", function()
{
    assert.fail("actual", "expected", "Error message");
});

Also, Mocha considers the test has failed if you call the done() function with a parameter.

For example:

it("should return empty set of tags", function(done)
{
    done(new Error("Some error message here"));
});

Though the first one looks clearer to me.

Answer 2

This simple throw is working for me

describe('Lead', () => {
  it('should create a new lead', async () => {
     throw 'not implemented'
  })
})

Answer 3

In the ES2017 async/await world chai-as-promised is not needed as much. Although simple rejections are one place chai-as-promised remains a little neater to use.

A catch is required if you want to test the error in more detail.

it.only('validation should fail', async function(){
    let body = { ... }
    let rules = eventsValidation.eventCreationRules()
    let valMessages = eventsValidation.eventCreationMessages()

    try {
        await indicative.validateAll(rules, body, valMessages)
    } catch (error) {
        expect(error).to.be.instanceOf(Error)
        expect(error.message).to.match(/Oh no!/)
        return
    }
    expect.fail(null, null, 'validateAll did not reject with an error')
    // or throw new Error('validateAll did not reject with an error')
})

async/await requires Node.js 7.6+ or a compiler like Babel

Answer 4

Use chai-as-promised, with native Mocha promise handlers.

var chai = require('chai').use(require('chai-as-promised'));
var should = chai.should(); // This will enable .should for promise assertions

You no longer need done, simply return the promise.

// Remove `done` from the line below
it.only('validation should fail', function(/* done */) {
    var body = {
        title: "dffdasfsdfsdafddfsadsa",
        description: "Postman Description",
        beginDate: now.add(3, 'd').format(),
        endDate: now.add(4, 'd').format()
    }

    var rules = eventsValidation.eventCreationRules();
    var valMessages = eventsValidation.eventCreationMessages();

    // Return the promise
    return indicative
        .validateAll(rules, body, valMessages)
        .should.be.rejected; // The test will pass only if the promise is rejected

    // Remove done, we no longer need it
    // done();
});