API Testing Tools

API Testing

APIs are a crucial component of software development. They transfer and connect logic and data across disparate applications and systems. When they are tested properly, the future performance of that API is much more likely to be effective.

Application Programming Interfaces, known as APIs for short, connect different layers or systems of applications. There are three layers in an application: the presentation (UI) layer, the service (API) layer, and a data layer. An application’s business logic is included as part of the API layer. It contains rules for how users interact with an app’s functions, data, or services. The service layer or API touches the presentation and data layers directly to offer continuous testing for Development and QA teams. Even though traditional testing focuses primarily on the UI (presentation) layer, API testing is becoming more widely used today.

There are a variety of different aspects of API testing that make requests to single or multiple API endpoints to validate the response for functional correctness, security, performance, or status checks. UI testing validates the feel and look of web interfaces, while ensuring that certain payment buttons work. On the other hand, API testing places more emphasis on performance bottleneck, security, and data response testing.

API Testing Types

Performance Testing: Only certain groups of industry professionals were able to execute load testing in a CD/CI environment. The Ready/API performance testing tool allows team members to use SOAP, RESTful, and other services to embed performance tests into the CI/CD pipeline.

End-to-End Testing: End-to-end testing validates data and information flow between several different API connections.

Integration Testing: Integration testing is one of the most commonly used types of API testing, as APIs are at the forefront of a majority of integrations between third-party or internal services.

Unit Testing: There are a lot of misnomers within the testing world. One of the easiest ways to think about APIs and “unit tests” is by using a single request to test an endpoint to search for one or multiple responses. This kind of testing can be performed through the command line and lightweight tools such as SoapUI or a cURL command.

API Testing Benefits

Coverage and Speed of Testing: It could take up to 30 hours to run over 300 UI tests, while 300 API tests can be run in under 3 minutes. Users will be able to find more bugs in a shorter amount of time, so that they can be fixed immediately.

Faster Resolution Time: Whenever an API test fails, users usually know where the issue is in the system. This reduces time triaging bugs between different team members, integrations, and builds. API tests generate a small, isolated footprint that improves the speed of MTTR stats, which are valuable KPIs for DevOps teams.

Efficient Test Maintenance: UIs are always moving and changing, based on their accessibility through browsers, screen orientation, or devices, which creates a scenario where tests must be rewritten in order to keep up with the code that’s currently in production. API changes are more infrequent and controlled. For instance, refactoring tests with API definitions such as OpenAPI take only seconds to perform.

Early Testing: Tests can be performed to validate accuracy in data and responses with API testing. Users no longer have to wait for their teams to complete their work or for entire applications to be created, as test cases are isolated and can be built right away.

Types of Bugs API Testing Can Detect

• Incorrectly structured response data (XML or JSON)
• Improper management of valid argument values
• High API response times and performance issues
• Multi-threading issues
• Security issues
• Difficulty with getting responses from API or connecting to API (reliability issues)
• Duplicate or missing functionality
• Unused flags
• Doesn’t handle error conditions properly

API Test Environment Setup

While API testing is different from other test software, the user will still need to set up the initial environment using a required set of parameters that invokes API to examine test results, as GUI is not available. There are many complexities involved with setting up testing environments for API automation. The server and database must be configured according to the application’s requirements. After the installation is complete, the API Function must be called to ensure that the API is working properly.

API Testing Best Practices

• Each API test case must be organized by test category.
• API test cases should be created for all possible API input combinations, to ensure complete test coverage.
• Call sequences should be well-executed and performed regularly.
• Users need to take special care when they are handling one-time call functions such as CloseWindow, Delete, etc.
• Users need to avoid “test chaining” in their development.
• Every test case needs to be independent and self-contained from dependencies.
• API functions must be prioritized to make it easy for users to perform tests.
• The parameters selection must be mentioned explicitly in the actual test case.
• The declarations of the APIs that are being called must be included on top of every test.

Final Thoughts

APIs contain procedures, functions, and class sets that represent the logic layer of a business. APIs must be properly tested so that the API application and the calling application don’t have any issues. API testing is one of the most important tests in software engineering.