Schema testing in GraphQL - Mini Project: Build & Apply

GraphQL Schema Testing Basics

📖 Scenario: You are building a simple GraphQL API for a bookstore. You want to make sure your schema is correct before adding real data.

🎯 Goal: Create a GraphQL schema with a Book type and a Query type. Then write a test query to check the schema structure.

📋 What You'll Learn

Define a Book type with fields id (ID!), title (String!), and author (String!)

Define a Query type with a field books that returns a list of Book

Write a test query to fetch id and title of all books

Ensure the schema is syntactically valid and the test query matches the schema

💡 Why This Matters

🌍 Real World

GraphQL schemas define how clients can request data from APIs in a clear and structured way.

💼 Career

Understanding schema design and testing is essential for backend developers working with GraphQL APIs.

1

Define the Book type

Create a GraphQL type called Book with these exact fields: id of type ID!, title of type String!, and author of type String!.

GraphQL

# Define the Book type
# Your code here

Need a hint?

Use the type keyword followed by the type name and curly braces to define fields.

2

Add the Query type

Add a GraphQL Query type with a field called books that returns a list of Book (use square brackets).

GraphQL

type Book {
  id: ID!
  title: String!
  author: String!
}

# Define the Query type with books field
# Your code here

Need a hint?

The Query type defines entry points for fetching data. Use square brackets to indicate a list.

3

Write a test query

Write a GraphQL query named GetBooks that fetches the id and title fields from the books query.

GraphQL

type Book {
  id: ID!
  title: String!
  author: String!
}

type Query {
  books: [Book]
}

# Write the GetBooks query
# Your code here

Need a hint?

Use the query keyword followed by the query name and select the fields inside curly braces.

4

Complete the schema with a simple resolver placeholder

Add a placeholder resolver function for books that returns an empty array. Use JavaScript syntax for the resolver object with a Query field containing books as a function returning [].

GraphQL

type Book {
  id: ID!
  title: String!
  author: String!
}

type Query {
  books: [Book]
}

query GetBooks {
  books {
    id
    title
  }
}

// Add resolver placeholder
// Your code here

Need a hint?

Resolvers connect schema fields to data. Here, return an empty array to keep it simple.