Integration tests with test server in GraphQL - Mini Project: Build & Apply

Integration Tests with Test Server

📋 What You'll Learn

💡 Why This Matters

🌍 Real World

Integration tests help developers verify that their GraphQL APIs work correctly before deploying to production. This reduces bugs and improves reliability.

💼 Career

Many software engineering roles require writing tests for APIs. Knowing how to set up test servers and write integration tests is a valuable skill for backend and full-stack developers.

1

Create a simple GraphQL schema with a Book type

Create a GraphQL schema string called typeDefs that defines a Book type with fields id (ID!), title (String!), and author (String!). Also define a Query type with a field book that takes an id argument of type ID! and returns a Book.

GraphQL

# Create the GraphQL schema string called typeDefs
# Your code here

Need a hint?

Use backticks to create a multi-line string. Define the Book type and Query type exactly as described.

2

Create a resolver for the book query

Create a constant called resolvers that defines a Query resolver with a book function. This function takes parent, args, and returns a book object with id, title, and author fields. Return the book with id equal to args.id, title as "Test Book", and author as "John Doe".

GraphQL

const typeDefs = `
  type Book {
    id: ID!
    title: String!
    author: String!
  }

  type Query {
    book(id: ID!): Book
  }
`;

// Create resolvers object with Query.book resolver
// Your code here

Need a hint?

Define the resolvers object with a Query field. The book resolver returns a fixed book object using args.id.

3

Create the test server using ApolloServer

Create a constant called server that is a new ApolloServer instance. Pass typeDefs and resolvers as options to the constructor.

GraphQL

const typeDefs = `
  type Book {
    id: ID!
    title: String!
    author: String!
  }

  type Query {
    book(id: ID!): Book
  }
`;

const resolvers = {
  Query: {
    book(parent, args) {
      return {
        id: args.id,
        title: "Test Book",
        author: "John Doe"
      };
    }
  }
};

// Create ApolloServer instance called server
// Your code here

Need a hint?

Import ApolloServer and create a new instance with the schema and resolvers.

4

Write an integration test to query the book by ID

Write an async function called testBookQuery. Inside, call server.executeOperation with a query string that requests book(id: "1") and asks for id, title, and author. Await the result and assign it to a variable called response. Then check that response.data.book.id equals "1", response.data.book.title equals "Test Book", and response.data.book.author equals "John Doe".

GraphQL

import { ApolloServer } from 'apollo-server';

const typeDefs = `
  type Book {
    id: ID!
    title: String!
    author: String!
  }

  type Query {
    book(id: ID!): Book
  }
`;

const resolvers = {
  Query: {
    book(parent, args) {
      return {
        id: args.id,
        title: "Test Book",
        author: "John Doe"
      };
    }
  }
};

const server = new ApolloServer({ typeDefs, resolvers });

// Write async function testBookQuery to run query and check response
// Your code here

Need a hint?

Use server.executeOperation with a query string. Check the response data fields for expected values.