Log response body on mocha test errors?

user_1337422 0
Viewed 2089

When running mocha tests using npm run test, is it possible to have the contents of the response body printed whenever a test fails with an error? 

chai.request(server)
  .post('/')
  .set('X-Access-Token', testUser.accessToken)
  .send(fields)
  .end((error, response) => {
    console.log(response.body);       // log this!
    response.should.have.status(201); // if this fails!
    done();
  });
});

In other words, could the afterEach function have access to error and response for each test?

afterEach(function(error, response) {
  if (error) console.log('afterEach', response.body);
});

We have useful error messages coming down in the response, so we find ourselves pasting that console.log line into the failing test to debug. It'd be nice to always see the response.body on each error.

chai npm mocha.js node.js response
1 Answers

OP here - I came up with an answer and figured I'd leave it here until someone comes up with a better one.

The reason it's not ideal is that it requires a single line in each test, which updates a shared variable currentResponse with that test's response. But if your tests span many files, you can maintain a global variable in your setup script:

// you can use a global variable if tests span many files
let currentResponse = null; 

afterEach(function() {
  const errorBody = currentResponse && currentResponse.body;

  if (this.currentTest.state === 'failed' && errorBody) {
    console.log(errorBody);
  }

  currentResponse = null;
});

And then each of your tests would update the current response, so we can log it in the afterEach, in the event that it fails.

describe('POST /interests', () => {
  it('400s if categoryName field is not present in the category', done => {
    const fields = [
      { language: 'en' },
    ];

    chai.request(server)
      .post('/interests')
      .set('X-Access-Token', testUser.accessToken)
      .send(fields)
      .end((error, response) => {
        currentResponse = response; // update it here
        response.should.have.status(400);
        done();
      });
  });

And this will output the response whenever there's an error, so you can see what the server returned.

user_13374220
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