mocha.jsshould.jschai

Chai, Mocha: Identify should assertion

I'm using mocha and chai as assertions.

I have several assertions in my spec:

Exp1.should.be.true
Exp2.should.be.true
Exp3.should.be.true

If one of them fails mocha writes "expected false to be true". Is there a way to identify them?

With expect I can do it:

expect(Exp1, 'Exp1').to.be true

Is something like this possible with should?

Solution

  • Apparently should does not support custom error messages at the moment.

    You can create your own helper for setting the message:

    var chai = require('chai'),
    should = chai.should();

// Helper definition - should be in a shared file
chai.use(function(_chai, utils) {
  _chai.Assertion.addMethod('withMessage', function(msg) {
    utils.flag(this, 'message', msg);
  });
});

// Sample usage
it('should fail', function() {
  var Exp1 = false;
  var Exp2 = false;
  Exp1.should.be.withMessage('Exp1').true;
  Exp1.should.withMessage('Exp2').be.true;
});