Integration tests with test server in GraphQL - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the main purpose of integration tests with a test server in GraphQL?

Integration tests with a test server check if different parts of the GraphQL API work together correctly, including the server, schema, and database, by running real queries and mutations.

beginner

Why do we use a separate test server instead of the production server for integration tests?

A separate test server prevents interference with real data and users, allowing safe testing of queries and mutations without affecting the live system.

intermediate

Which component is essential to start before running integration tests on a GraphQL API?

The test server must be started with the full GraphQL schema and connected to a test database or mock data source to simulate real interactions.

intermediate

How can you verify the output of a GraphQL query in an integration test?

By sending the query to the test server and checking the returned JSON response matches the expected data structure and values.

intermediate

What is a common tool or library used to run integration tests against a GraphQL test server?

Tools like Jest combined with Apollo Server Testing utilities or supertest can be used to send queries and mutations to the test server and assert results.

What does an integration test with a GraphQL test server primarily check?

A If the database schema is normalized

B If the frontend UI looks good

C If the GraphQL API components work together correctly

D If the server hardware is fast enough

Integration tests focus on how different parts of the API work together, not UI or hardware.

Why should integration tests use a test database instead of the production database?

A To avoid corrupting real data

B Because test databases are faster

C To save disk space

D Because production databases do not support GraphQL

Using a test database protects real data from accidental changes during testing.

Which of the following is needed to run integration tests on a GraphQL API?

A A web browser

B Only the frontend code

C A text editor

D A running test server with schema and data

Integration tests require a test server running the GraphQL schema and connected to data.

How do you check if a GraphQL query returns the correct data in an integration test?

A Verify the query syntax only

B Compare the JSON response to expected results

C Check the server CPU usage

D Look at the server logs

The test compares the actual response data to what is expected to confirm correctness.

Which tool is commonly used to write integration tests for GraphQL servers?

A Jest

B Photoshop

C Excel

D Docker Compose

Jest is a popular testing framework used for writing integration tests in JavaScript/GraphQL projects.

Explain the steps to set up and run an integration test with a GraphQL test server.

Think about what you need before running queries and how to verify results.

Why is it important to isolate integration tests from the production environment?

Consider risks of running tests on live systems.

Practice

1. What is the main purpose of using a test server in GraphQL integration tests?

easy

A. To speed up the production server

B. To run queries and mutations safely without affecting real data

C. To replace the database permanently

D. To generate random data automatically

Solution

1. Step 1: Understand the role of a test server

   A test server is a safe environment that mimics the real server but does not affect actual data.

2. Step 2: Identify the purpose in integration tests

   Integration tests use the test server to check if queries and mutations work together correctly without risk.

3. Final Answer:

   To run queries and mutations safely without affecting real data -> Option B

4. Quick Check:

   Test server = safe testing environment [OK]

Hint: Test server isolates tests from real data changes [OK]

Common Mistakes:

• Thinking test server speeds up production
• Confusing test server with permanent database replacement
• Assuming test server auto-generates data

2. Which of the following is the correct way to start a test server for GraphQL integration tests using Apollo Server?

easy

A. const server = ApolloServer(); server.startServer();

B. const server = ApolloServer(typeDefs, resolvers); server.run();

C. const server = new ApolloServer({ typeDefs, resolvers }); await server.listen();

D. const server = new ApolloServer({ typeDefs, resolvers }); await server.start();

Solution

1. Step 1: Recall Apollo Server setup

   Apollo Server requires creating an instance with typeDefs and resolvers, then calling start() before listen().

2. Step 2: Identify correct method to start server

   The correct method to start the server is await server.start(); before running listen().

3. Final Answer:

   const server = new ApolloServer({ typeDefs, resolvers }); await server.start(); -> Option D

4. Quick Check:

   Use server.start() before listen() [OK]

Hint: Remember to call await server.start() before listen() [OK]

Common Mistakes:

• Calling listen() without starting server
• Using incorrect constructor syntax
• Assuming server.run() or startServer() exist

3. Given this test code snippet for a GraphQL query on a test server:

const result = await server.executeOperation({ query: `query { user(id: 1) { name } }` }); console.log(result.data.user.name);

What will be printed if the user with id 1 has the name "Alice"?

medium

A. undefined

B. null

C. "Alice"

D. Error: user not found

Solution

1. Step 1: Understand executeOperation result

   executeOperation returns an object with data containing the query result if successful.

2. Step 2: Check the query and expected data

   The query requests user with id 1 and its name. If user exists with name "Alice", result.data.user.name will be "Alice".

3. Final Answer:

   "Alice" -> Option C

4. Quick Check:

   Query result matches user name "Alice" [OK]

Hint: executeOperation returns data object with query results [OK]

Common Mistakes:

• Expecting undefined if user exists
• Confusing null with undefined
• Assuming error thrown instead of null result

4. You wrote this test code but it throws an error:

const result = await server.executeOperation({ query: `mutation { addUser(name: "Bob") { id } }` });

What is the most likely cause?

medium

A. The mutation name is incorrect or not defined in schema

B. The query should be a GET request, not mutation

C. executeOperation cannot run mutations

D. Missing await keyword before server.executeOperation

Solution

1. Step 1: Check mutation usage in test

   executeOperation supports mutations, so that is not the issue.

2. Step 2: Verify mutation name and schema

   If mutation name addUser is not defined in the schema, the server throws an error.

3. Final Answer:

   The mutation name is incorrect or not defined in schema -> Option A

4. Quick Check:

   Mutation must exist in schema to run [OK]

Hint: Check mutation name matches schema exactly [OK]

Common Mistakes:

• Thinking executeOperation can't run mutations
• Forgetting to await executeOperation
• Confusing query and mutation types

5. You want to write an integration test that checks if a mutation correctly adds a user and then a query fetches that user. Which sequence correctly tests this on a GraphQL test server?

hard

A. Run mutation with executeOperation, then run query with executeOperation, check query result matches mutation data

B. Run query first, then mutation, then check mutation result

C. Run mutation and query in parallel without waiting, then check results

D. Only run mutation; query testing is unnecessary in integration tests

Solution

1. Step 1: Understand integration test flow

   Integration tests verify that mutations affect data and queries reflect those changes.

2. Step 2: Correct test sequence

   First run mutation to add user, then query to fetch user, then compare results to confirm correctness.

3. Final Answer:

   Run mutation with executeOperation, then run query with executeOperation, check query result matches mutation data -> Option A

4. Quick Check:

   Mutation then query to verify changes [OK]

Hint: Test mutation first, then query to confirm data change [OK]

Common Mistakes:

• Running query before mutation
• Running mutation and query in parallel without order
• Skipping query test after mutation