Testing GraphQL

Testing a GraphQL API can seem intimidating at first, but it's actually quite simple. In this post, we'll go over the basics of testing a GraphQL API using the popular testing library Jest.

First, let's make sure we have Jest installed. If you're using npm, run the following command:

npm install --save-dev jest

Next, let's create a test file for our GraphQL API. In this example, we'll create a file called graphql.test.js in our project's __tests__ directory.

In this file, we'll need to import the request method from the jest-gql library, which is a helper library for testing GraphQL APIs.

import { request } from 'jest-gql';

Next, let's define our GraphQL query. In this example, we'll be testing a simple query that fetches a user's name and email address:

const query = `
  query User($id: ID!) {
    user(id: $id) {
      name
      email
    }
  }
`;

Now, we can write our test. In this example, we'll test that the query returns the expected data for a user with an id of 1:

test('fetches user data', async () => {
  const variables = { id: 1 };
  const { data } = await request(query, variables);

  expect(data.user.name).toEqual('John Doe');
  expect(data.user.email).toEqual('[e-mail]');
});

That's it, short but sweet! With just a few lines of code, we've written a test that will verify that our GraphQL API is working as expected.

Of course, there are many other things you can test with Jest, such as the response time, error handling, and more. For more information on testing with Jest, check out the Jest documentation.