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: "Postman Description",         beginDate: now.add(3, 'd').format(),         endDate: now.add(4, 'd').format()     }       var rules = eventsValidation.eventCreationRules();     var valMessages = eventsValidation.eventCreationMessages();      indicative         .validateAll(rules, body, valMessages)         .then(function(data) {             console.log("SHOULD NOT GET HERE");             should.fail("should not get here");             done();          })         .catch(function(error) {             console.log("SHOULD GET HERE");             console.log(error);         });     done(); }); 

The test execution path is correct. When I have validating data, it goes to "SHOULD NOT GET HERE". The test is really to make sure it doesn't. And when I put in non validating data the code does go to "SHOULD GET HERE". So the validation rules work.

What I'm trying to do is make sure the test fails when when I have bad validation data and it validates. However when I run it as it is with good data it validates, runs the fail, but mocha still marks it as the passing. I want it to fail if the execution gets to "SHOULD NOT GET HERE".

I've tried throw new Error("fail"); as well with no luck. In both cases it actually seems to run the code in the .catch block as well.

Any suggestions? I found solutions for this in a similar question. This question is written because those solutions don't seem to be working for me.

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

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