How to Test GraphQL APIs

This year, we’ve witnessed a significant shift in the tech landscape. Industry giants like Amazon (AWS), Facebook, Twitter, GitHub, and others are embracing GraphQL APIs, both for their internal operations and external interactions.

GraphQL, hailed as the SQL for APIs, is more than a query language – It's a runtime that efficiently retrieves data from databases. In contrast to RESTful APIs, which often require aggregating data from multiple server responses, GraphQL empowers applications to fetch all the necessary data in a single request.

This transformation is remarkable, but there's a notable gap in resources when it comes to GraphQL testing. While testing RESTful API endpoints is relatively straightforward, GraphQL poses unique challenges because many existing tools do not fully support it.

Let's dive into how to test GraphQL APIs, explore the differences compared to testing RESTful APIs, and highlight some key best practices.

What is GraphQL?

GraphQL serves as a query language for APIs and facilitates the execution of queries by fetching data from a database. Unlike REST APIs, which rely on multiple resource URLs, GraphQL retrieves all required data in one request, using types and fields instead of individual endpoints with predefined responses.

GraphQL services, known as resolvers, can be implemented in any programming language, while the GraphQL schema language ensures consistency in a language-agnostic manner. Schemas define object types, each representing a fetchable object with associated fields. This offers a familiar structure for developers.

For example:

            
type Character {
    name: String!
    appearsIn: [Episode]!
}
        

Each field on a type is backed by a resolver function, provided by the GraphQL server developer. When a field is executed, the corresponding resolver generates the next value. This approach streamlines backend development by eliminating the need for writing specific responses or versioning APIs. Front-end teams benefit from requesting only the required data, enhancing both backend and frontend performance.

What is GraphQL Testing?

Most functional GraphQL testing aims to validate that schemas, queries, and mutations perform as expected on the front-end. A growing ecosystem of tools supports these tests, tailored to various programming languages, platforms, and testing infrastructures, accommodating diverse testing requirements.

For instance, EasyGraphQL is a popular functional testing tool for JavaScript developers. It integrates seamlessly with libraries like Mocha, enabling straightforward API response verification as part of automated test suites.

Here's an example of an assertion using EasyGraphQL:

            
t('should pass if the query is valid', () => {
    const validQuery = `
        {
            getUserByTestResult(result: 4.9) {
                email
            }
        }
    `

    tester.test(true, validQuery)
})
        

GraphQL API Testing Best Practices

Several types of tests are essential:

• Query tests: Ensures a query (along with any parameters) returns the expected response.
• Mutation tests: Verifies a query (and related parameters) successfully store data in a database.
• Load tests: Assess API performance under high request volumes while meeting SLAs.
• Security tests: Confirms APIs do not expose sensitive data without appropriate safeguards.

When testing external web services utilizing GraphQL, like GitHub V4, consider simulating responses to reduce unnecessary usage and shorten test execution times. Mocks and fixtures can simulate these services effectively, but in some cases, virtualization aids in analyzing usage and metrics.

REST vs. GraphQL

"REST (Representational State Transfer) and GraphQL are two popular approaches for building APIs, each with its own strengths.

REST, a well-established standard, uses a set of predefined endpoints to expose data. It's known for its simplicity and ease of caching, making it great for many applications.

On the other hand, GraphQL offers more flexibility. With GraphQL, clients can request exactly the data they need, reducing over-fetching and under-fetching of data. It's ideal for situations where efficiency and minimizing network requests are critical.

Choosing between REST and GraphQL depends on your project's specific requirements. REST is a solid choice for simpler applications, while GraphQL shines when you need fine-grained control over your API interactions. Understanding the unique benefits of each can help you make the right decision for your API design."

Ways to Use ReadyAPI for GraphQL

ReadyAPI simplifies GraphQL testing, including query and mutation evaluation, performance assessment through load testing, and web service virtualization. It streamlines the creation, management, and execution of these automated tests in a centralized interface, reducing the need for extensive code development and accelerating API quality for Agile and DevOps teams.

ReadyAPI seamlessly integrates with tools like Swagger, enabling you to import API definitions for immediate testing and real-time traffic recording. With virtualization capabilities, you can eliminate dependencies on third-party APIs, enhancing test suite speed and minimizing unnecessary API consumption.

Testing GraphQL within ReadyAPI is effortless. You write queries using GraphQL syntax, specify query variables in JSON format, and execute tests. Assertions validate responses using properties like contains, equals, counts, and even regular expressions.

These tests readily integrate with Jenkins, Docker, Visual Studio Team Services, TeamCity, and other continuous integration or builder tools your team employs. You can view test results, review errors, and access standard functionality via a user-friendly web-based interface, simplifying the testing process compared to command-line alternatives.

The Bottom Line

GraphQL's popularity continues to surge in 2023 with prominent tech companies, not just Facebook, embracing it for both internal and external APIs. Testing GraphQL doesn't have to be complex; it requires the right tools and processes.

To learn more about GraphQL, watch our on-demand webinar. If you’re ready to explore the benefits of ReadyAPI, sign up for a free trial today and experience firsthand how it streamlines and automates your API tests.