Contract Testing for Graph APIs

1. Introduction

Contract testing is a crucial aspect of ensuring that your Graph APIs can communicate effectively with other services without breaking changes. In this lesson, we will explore the key concepts, processes, and best practices for implementing contract testing specifically for Graph APIs.

2. Key Concepts

3. Step-by-Step Process

Follow these steps to implement contract testing for your Graph APIs:

1. Define the Contract: Specify the required inputs and expected outputs for your Graph API. This includes defining query structures and response formats.
2. Implement Consumer Tests: Write tests from the consumer's perspective to verify that the API provides the expected data structure.

   
                   import { expect } from 'chai';
                   import { request } from 'graphql-request';
   
                   const query = `{
                       user(id: "1") {
                           name
                           email
                       }
                   }`;
   
                   request('http://localhost:4000/graphql', query).then(data => {
                       expect(data.user).to.have.property('name');
                       expect(data.user).to.have.property('email');
                   });
                   

3. Implement Provider Tests: Ensure that the provider adheres to the contract defined by the consumer.

   
                   import { expect } from 'chai';
                   import { createServer } from 'http';
                   import { ApolloServer } from 'apollo-server';
   
                   const server = new ApolloServer({ typeDefs, resolvers });
                   
                   server.listen().then(({ url }) => {
                       const query = `{
                           user(id: "1") {
                               name
                               email
                           }
                       }`;
                       return request(url, query);
                   }).then(data => {
                       expect(data.user).to.deep.equal({
                           name: "Jane Doe",
                           email: "jane.doe@example.com"
                       });
                   });
                   

4. Run the Tests: Execute both consumer and provider tests regularly, especially after changes to the API or database schema.
5. Monitor and Update: As your API evolves, ensure to update the contracts and tests accordingly.

4. Best Practices

• Use versioning for your Graph APIs to manage breaking changes.
• Automate contract testing in your CI/CD pipeline.
• Maintain clear documentation of your API contracts.
• Encourage collaboration between API consumers and providers.
• Regularly review and refactor tests for efficiency and coverage.

5. FAQ