How to assert validation errors of mongoose using supertest?

Question

I am trying to validate using supertest that the response returned by a REST endpoint contains the validation error of moongose validation which looks like below

errors: Object {
  firstName: Object {
    kind: 'required',
    message: 'Path `firstName` is required.',
    name: 'ValidatorError',
    path: 'firstName',
    properties: Object {
      message: 'Path `{PATH}` is required.',
      path: 'firstName',
      type: 'required'
    },
  }

I am writing following test

it('should return well formatted error response when first name is missing', function(done){
    var user = {lastName:"Ranger", email:"dan.ranger@gmail.com"};
    request(app)
    .post('/api/user')
    .send(user)
    .end(function(err, res){
        res.body.should.have.property("path", "firstName");
        done();
    });
});

But I am getting following error

AssertionError: expected Object {
errors: Object {
  firstName: Object {
    kind: 'required',
    message: 'Path `firstName` is required.',
    name: 'ValidatorError',
    path: 'firstName',
    properties: Object {
      message: 'Path `{PATH}` is required.',
      path: 'firstName',
      type: 'required'
    },
  }
},
message: 'User validation failed',
name: 'ValidationError',
} to have property path
  at Test.<anonymous> (test/userTests.js:23:25)
  at net.js:1276:10

How can I write such asserts?

Answer 1

You are asserting that res.body has property 'path', however res.body is the parent object which only contains the properties errors, message, and name.

You could test for these properties, or you can access the nested error object as follows:

.end(function(err, res){
  res.body.errors.firstName.should.have.property("path")
  done();
});

It is likely more convenient just to test properties on the parent object, as this should prove sufficient.