Implementing automated testing for Javascript GraphQL servers

27 Sep 2023

With the rise in popularity of GraphQL as a data-fetching API, building efficient and bug-free GraphQL servers has become essential. One way to ensure the quality of your codebase is by implementing automated testing. In this blog post, we will explore how to set up and write automated tests for JavaScript GraphQL servers.

Why Automated Testing?

Automated testing allows developers to catch bugs early in the development process and verify that their code meets the required functionality. It also helps to prevent regressions when introducing new features or making changes to existing ones.

Setting Up the Testing Environment

Step 1: Install Dependencies

To get started, make sure to have Node.js and NPM (Node package manager) installed on your machine. You will also need to install the following dependencies:

npm install --save-dev jest supertest graphql

jest: A powerful JavaScript testing framework.
supertest: A library to make HTTP requests and test API endpoints.
graphql: A JavaScript library for parsing and manipulating GraphQL schemas.

Step 2: Create a Test File

Create a new file called server.test.js in the same directory as your GraphQL server code. This file will contain all the test cases for your GraphQL server. You can organize your test files into separate directories based on the functionality being tested.

Writing Test Cases

For testing GraphQL servers, we will be using a combination of unit and integration tests. Unit tests focus on testing individual functions, while integration tests validate the interaction between different components.

Here’s an example of a simple test case to verify the functionality of a GraphQL query:

const request = require('supertest');
const app = require('./server'); // Import your GraphQL server code

describe('GraphQL Server', () => {
  it('should return the correct user information', async () => {
    const response = await request(app)
      .post('/graphql')
      .send({ query: '{ user(id: 1) { name, email } }' })
      .set('Accept', 'application/json')
      .expect('Content-Type', /json/)
      .expect(200);

    expect(response.body.data.user.name).toEqual('John Doe');
    expect(response.body.data.user.email).toEqual('john.doe@example.com');
  });
});

In this example, we are using the request object from the supertest library to make a POST request to the /graphql endpoint of our server. We send a GraphQL query as the request body and assert that the response is valid and contains the expected user information.

Running the Tests

To run the tests, execute the following command in your terminal:

npm test

This will trigger the test runner (Jest) which will execute all the test cases and provide you with the test results.

Conclusion

By implementing automated testing for your JavaScript GraphQL servers, you can ensure that your code works as expected and is robust. Automated testing allows you to catch bugs early, maintain code quality, and provide confidence in your application’s functionality, allowing you to iterate faster and deploy with more confidence.

#testing #automation