Unit Testing GraphQL Resolvers

Unit testing is crucial for ensuring the reliability of your GraphQL API. When we unit test resolvers, we focus on testing individual components in isolation.

• Isolation: We test a resolver without needing a running server or database.
• Correctness: Verify the resolver's logic, argument handling, and data transformation.
• Speed: Unit tests run very fast, providing quick feedback during development.

This lesson will guide you through writing effective unit tests for your Spring Boot GraphQL resolvers.

Before testing, let's briefly recall how resolvers are structured in Spring Boot. They are typically Spring @Controller components with methods annotated for GraphQL operations like @QueryMapping or @MutationMapping.

These methods often depend on other Spring @Service components to fetch or manipulate data, which is where mocking comes in handy for testing.