Unit Testing

The last step of this tutorial is to add some unit tests to the ApiController.

A unit test file ends with the spec.ts extension and is usually placed next to the file it is testing.

Create a new file config/test.json to set the database uri.

{
  "mongodb": {
    "uri": "mongodb://localhost:27017/test-my-app"
  }
}

Then open the file api.controller.spec.ts and replace its content.

// std
// The `assert` module provides a simple set of assertion tests.
import { ok, strictEqual } from 'assert';

// 3p
import { Config, createController, getHttpMethod, getPath, isHttpResponseOK } from '@foal/core';
import { connect, disconnect } from 'mongoose';

// App
import { Todo } from '../models';
import { ApiController } from './api.controller';

// Define a group of tests.
describe('ApiController', () => {

  let controller: ApiController;

  // Create a connection to the database before running all the tests.
  before(async () => {
    const uri = Config.getOrThrow('mongodb.uri', 'string');
    connect(uri, { useNewUrlParser: true, useCreateIndex: true, useUnifiedTopology: true });

    await Todo.deleteMany({});
  });

  // Close the database connection after running all the tests whether they succeed or failed.
  after(() => disconnect());

  // Create or re-create the controller before each test.
  beforeEach(() => controller = createController(ApiController));

  // Define a nested group of tests.
  describe('has a "getTodos" method that', () => {

    // Define a unit test.
    it('should handle requests at GET /.', () => {
      // Throw an error and make the test fail if the http method of `getTodos` is not GET.
      strictEqual(getHttpMethod(ApiController, 'getTodos'), 'GET');
      // Throw an error and make the test fail if the path of `getTodos` is not /todos.
      strictEqual(getPath(ApiController, 'getTodos'), '/todos');
    });

    // Define a unit test.
    it('should return an HttpResponseOK.', async () => {
      // Create fake todos.
      const todo1 = new Todo();
      todo1.text = 'Todo 1';

      const todo2 = new Todo();
      todo2.text = 'Todo 2';

      // Save the todos.
      await Promise.all([
        todo1.save(),
        todo2.save()
      ]);

      const response = await controller.getTodos();
      ok(isHttpResponseOK(response), 'response should be an instance of HttpResponseOK.');

      const body = response.body;

      ok(Array.isArray(body), 'The body of the response should be an array.');
      strictEqual(body[0].text, 'Todo 1');
      strictEqual(body[1].text, 'Todo 2');
    });

  });

});

As a controller method returns an HttpResponse object, it is really easy to test the status and body of the response.

If the controller method takes a Context object as argument, you can instantiate one like this: new Context({ /* content of the express request object */}).

Run the tests.

npm run test

This command watches at your tests and tested files in the app/ directory. When a file is modified, it automatically recompiles and re-runs your tests.

You should now end up with this output:

Congratulations! You have reached the end of this tutorial!

If you have any questions, feel free to open an issue on Github!