Integration tests with test server in GraphQL - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ query_result

intermediate

What is the result of this GraphQL query in the test server?

Given a test server with a simple schema for books and authors, what will be the output of the following query?

{ books { title author { name } } }

GraphQL

query { books { title author { name } } }

A SyntaxError: Unexpected token in query

B [{"title": "1984"}, {"title": "Brave New World"}]

C [{"title": "1984", "author": null}, {"title": "Brave New World", "author": null}]

D [{"title": "1984", "author": {"name": "George Orwell"}}, {"title": "Brave New World", "author": {"name": "Aldous Huxley"}}]

💡 Hint

Remember the test server has mock data for books and their authors.

The query requests the book titles and their authors' names. The test server returns both fields correctly.

📝 Syntax

intermediate

Which option causes a syntax error in this GraphQL mutation?

Consider this mutation to add a new book:

mutation { addBook(title: "Dune", authorId: 3) { id title } }

Which option below will cause a syntax error when run on the test server?

A mutation { addBook(title: "Dune", authorId: 3) { id title } }

B mutation { addBook(title: "Dune", authorId: 3) { id, title } }

C mutation { addBook(title: "Dune" authorId: 3) { id title } }

D } } eltit di { )3 :dIrohtua ,"enuD" :eltit(kooBdda { noitatum

💡 Hint

Check the commas between arguments carefully.

Option C is missing a comma between arguments, causing a syntax error.

❓ optimization

advanced

How to optimize this GraphQL query to reduce data fetched in integration tests?

This query fetches all fields of books and authors:

{ books { id title author { id name bio } } }

Which option optimizes the query to fetch only necessary fields for a test that checks book titles and author names?

A { books { title author { name } } }

B { books { id title author { id name bio } } }

C { books { title author { bio } } }

D { books { id author { id name } } }

💡 Hint

Fetch only fields needed for the test to reduce data size.

Option A fetches only book titles and author names, minimizing data transfer and speeding tests.

🔧 Debug

advanced

Why does this integration test fail with a null author?

Test query:

{ books { title author { name } } }

Test server returns author as null for some books. What is the most likely cause?

A The query syntax is incorrect causing author field to be null.

B The test server's mock data has books without linked authors.

C The test server does not support nested queries.

D The client query is missing the author field.

💡 Hint

Check the mock data completeness in the test server.

If mock data lacks author info for some books, author will be null in results.

🧠 Conceptual

expert

What is the main benefit of using a test server for integration tests in GraphQL?

Choose the best explanation for why integration tests use a test server instead of the real backend.

A It isolates tests from real backend changes and allows controlled data for predictable results.

B It runs faster because it uses the real backend with caching enabled.

C It avoids writing queries by generating data automatically.

D It replaces the need for unit tests by testing everything at once.

💡 Hint

Think about test reliability and control over data.

Test servers isolate tests from backend changes and provide stable, controlled data for consistent test results.