Why is supertest returning an error when everything passes?

Question

My test looks like:

it('should create a user with an email address and password', function(done) {
  return request.post('/v1/users').send(defaultUser).expect(200).expect(function(res) {
    console.log(res.body);
    res.body.should.have.property('id');
    res.body.should.have.property('name');
    res.body.should.have.property('email');
    res.body.should.have.property('username');
    return res.body.should.have.property('entities')["with"].lengthOf(1);
  }).end(done);
});

res.body looks like

{ id: 17,
  name: 'Satoshi Nakamoto',
  email: 'snakamoto@mysite.com',
  username: 'snakamoto',
  api_key: '510e55d2c15b0617757bd463b3653ec8',
  entities: [ { id: 17, name: 'Satoshi Nakamoto Default Entity' } ] }

So it has all of the appropriate fields. The error that I get is

  1) User Interactions should create a user with an email address and password:
 Error: [object Object]
at Test.assert (/Users/shamoon/Sites/mysite/mysite-api/node_modules/supertest/lib/test.js:218:48)
at Server.assert (/Users/shamoon/Sites/mysite/mysite-api/node_modules/supertest/lib/test.js:132:12)
at Server.g (events.js:180:16)
at Server.emit (events.js:92:17)
at net.js:1276:10
at process._tickCallback (node.js:419:13)

What am I doing wrong?

Answer 1

This is the problem:

return res.body.should.have.property('entities')["with"].lengthOf(1);

Supertest treats a falsy value returned from an expect call that takes a function to mean "all is okay" and a non-falsy value to mean "there's been a problem". What you return is most likely not falsy. Most implementations of should do return objects which allow chaining of flags (e.g. foo.should.something(...).and.something(...).and...). Objects are non-falsy and thus make expect think the test has failed.