Testing the success scenario

We have covered almost all of the edge cases. Now, we must implement the happy path scenario, where our endpoint is called as intended, and where we are actually creating the user and storing it in our database.

Let's carry on with the same process and start by defining a scenario:

Scenario: Minimal Valid User

  When the client creates a POST request to /users
  And attaches a valid Create User payload
  And sends the request
  Then our API should respond with a 201 HTTP status code
  And the payload of the response should be a string
  And the payload object should be added to the database, grouped under the "user" type

All steps are defined except the second, fifth, and last step. The second step can be implemented by using our getValidPayload method to get a valid payload, like so:

When(/^attaches a valid (.+) payload$/, function (payloadType) {
  this.requestPayload = getValidPayload(payloadType);
  this.request
    .send(JSON.stringify(this.requestPayload))
    .set('Content-Type', 'application/json');
});

The fifth step is a variation of the Then('the payload of the response should be a JSON object') step definition we have already defined, and therefore we can simply modify it to make it more generic:

Then(/^the payload of the response should be an? ([a-zA-Z0-9, ]+)$/, function (payloadType) {
  const contentType = this.response.headers['Content-Type'] || this.response.headers['content-type'];
  if (payloadType === 'JSON object') {
    // Check Content-Type header
    if (!contentType || !contentType.includes('application/json')) {
      throw new Error('Response not of Content-Type application/json');
    }

    // Check it is valid JSON
    try {
      this.responsePayload = JSON.parse(this.response.text);
    } catch (e) {
      throw new Error('Response not a valid JSON object');
    }
  } else if (payloadType === 'string') {
    // Check Content-Type header
    if (!contentType || !contentType.includes('text/plain')) {
      throw new Error('Response not of Content-Type text/plain');
    }

    // Check it is a string
    this.responsePayload = this.response.text;
    if (typeof this.responsePayload !== 'string') {
      throw new Error('Response not a string');
    }
  }
});

For the last step, however, we actually need a database to write to. But we have already achieved a lot in this chapter. So let's review what we have done up to this point, and set up a database in the next chapter!