GraphQL interview questions — Hard
150 hard-level GraphQL questions from our API Testing bank, each with the correct answer and an explanation of why it is correct.
What this covers
GraphQL appears throughout API Testing interviews. At hard level, interviewers are typically checking depth under pressure — edge cases, failure modes, performance characteristics, and the trade-offs you accepted. Work through these, then explain your answer out loud; the second part is what interviews actually test.
4 example questions
1. Regarding GraphQL, which of the following is a false statement?
- A. Aliases let one query request the same field multiple times with different arguments.
- B. GraphQL clients cannot choose which fields are returned.correct
- C. Fragments define reusable field selections shared across queries.
- D. The schema (SDL) defines types, fields, and operations, enabling contract-style validation.
Why: The selected statement is false. The other options are accurate statements about GraphQL.
2. Which statement about GraphQL is NOT correct?
- A. Nested queries can cause performance issues, so depth and complexity limits should be tested.
- B. Subscriptions are used for one-time data fetches only.correct
- C. Fragments define reusable field selections shared across queries.
- D. GraphQL responses can return HTTP 200 while containing an errors array in the body.
Why: The selected statement is false. The other options are accurate statements about GraphQL.
3. Which of the following statements about GraphQL is FALSE?
- A. Over-fetching tests verify the API returns only requested fields.
- B. A GraphQL server always returns HTTP 500 when any field errors occur.correct
- C. Aliases let one query request the same field multiple times with different arguments.
- D. GraphQL responses can return HTTP 200 while containing an errors array in the body.
Why: The selected statement is false. The other options are accurate statements about GraphQL.
4. Identify the INCORRECT statement about GraphQL:
- A. GraphQL exposes a single endpoint where clients specify exactly the fields they need.
- B. Variables parameterize GraphQL operations instead of string concatenation.
- C. GraphQL responses can return HTTP 200 while containing an errors array in the body.
- D. GraphQL clients cannot choose which fields are returned.correct
Why: The selected statement is false. The other options are accurate statements about GraphQL.