API test automation

Learn how API test automation enables teams to continuously validate their work and catch issues before they reach production.

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What is API test automation?

API test automation is the process of using a testing tool to programmatically execute API tests at certain times or frequencies, or in CI/CD pipelines. It is particularly important for agile development teams, as it enables them to maintain fast-paced development cycles while continuously and systematically verifying that their API is working as expected. API test automation helps prevent breaking changes from reaching production, and it is intended to augment—rather than replace—the manual approach. Teams that automate their API tests are able to deliver new features quickly and confidently while conserving developer bandwidth.

Here, we'll review the role that API test automation plays in today's software landscape—and discuss how it helps teams shift left. We'll then explore some key benefits and best practices for API test automation, and explain how the Postman API Platform enables teams to automate API test runs throughout the API lifecycle.

What role does API test automation play in an API-first world?

API testing is an essential part of the API-first development model, as it enables teams to verify their API's quality by confirming it is working as expected. But ensuring API quality is only half the battle; teams must also iterate quickly in order to release new features that will help them stay competitive. These teams typically follow the agile development methodology, which involves shipping small code changes multiple times a day or week. While this approach supports fast-paced development cycles, it also increases the risk of breaking changes.

API test automation has emerged as the answer to this problem, as it helps teams remain agile without compromising API quality or losing test coverage. Automated API tests can be executed on a schedule, or they can be executed within CI/CD pipelines whenever a developer pushes new code. This hands-free approach can be seamlessly integrated into any development team's existing workflow, so they don't have to worry about issues falling through the cracks.

Postman Test Automation. Illustration.

How does API test automation help teams shift left?

Historically, software testing has been performed by dedicated QA teams at the very end of long development cycles. This approach is time-consuming and prone to human error, and it can lead to delays as teams work to fix unexpected issues at the last minute.

Shift-left testing involves running tests earlier and more frequently during the development process, which helps remove this bottleneck. Automation plays a key role in the shift-left approach, as it lets developers automatically execute tests within CI/CD pipelines whenever they push new code. This enables development teams—including those that are responsible for building APIs—to continuously validate their work and catch issues before they reach production. Teams that leverage automated testing can therefore release features quickly, confidently, and cost-effectively.

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What are some of the benefits of API test automation?

Like manual API testing, API test automation enables teams to confirm that their API is working as expected. However, it also offers several additional benefits that improve developer workflows and support rapid iteration. By automating API tests, teams can:

Detect issues as soon as they are introduced

Test automation enables developers to surface issues while they work. For instance, teams can configure their CI/CD pipeline to automatically execute API tests after every code push, which provides immediate feedback while the code is still in progress. If the tests identify an issue, the developer can fix it immediately—before it gets deployed to production and causes user-facing issues.

Save time and resources

Testing at the very end of a development cycle puts enormous strain on QA teams, who are often responsible for vetting every piece of functionality on a tight schedule. This approach requires a significant amount of time and effort, and it can also result in delays as development teams work to fix unexpected issues. Automated API testing distributes the testing load across the API lifecycle, which shortens feedback loops, improves efficiency, and enables teams to bring new features to market as quickly as possible.

What are some best practices for API test automation?

The following best practices help ensure that API development teams are able to implement a test automation strategy that is effective, reliable, and able to meet their unique needs:

Don't automate flaky tests

As discussed above, one of the primary benefits of API test automation is its ability to save time and increase productivity. However, it's important for teams to be judicious when deciding which tests to automate. For instance, tests that include complex logic may produce false positives, which can cause teams to waste time troubleshooting issues that don't exist. False positives can also lead to test fatigue, in which legitimate failures are overlooked. Teams should therefore only automate simple, straightforward tests—and implement retry logic to confirm failures.

Reduce the risk of human error

Manual testing is an important part of any development team's workflow, but it is prone to human error. For instance, a developer may execute a test incorrectly or misinterpret its results. API test automation standardizes test executions, which reduces the risk of human error while improving confidence and morale.

Run tests in parallel

Automated API testing should be fast and efficient—especially when it occurs within CI/CD pipelines. If an automated test suite takes an hour to execute after every commit, the developer will have to choose between pausing their work or pressing ahead without feedback. One way to ensure that test suites execute as quickly as possible is to run tests in parallel rather than in sequence. This approach enables teams to run tests against different browsers, devices, and operating systems without introducing a bottleneck.

Use a testing tool that is compatible with the rest of your workflow

In order to unlock the full benefits of API test automation, teams must choose a testing tool that is compatible with their existing workflows. For instance, it should integrate seamlessly with their chosen CI/CD pipeline—and offer failure notifications via email or Slack. Some teams may also want a testing solution that enables them to forward test data to monitoring or incident response tools, such as Datadog, New Relic, or Opsgenie.

What are some challenges of API test automation?

Teams must negotiate a variety of challenges as they develop and fine-tune their API test automation strategy, including:

  • Speed: API test automation is intended to facilitate rapid iteration, and slow tests will compromise that goal. Complex test data and slow dependencies can negatively impact execution times, as can sequential execution and long setup and tear-down processes. Teams must therefore carefully consider these trade-offs when developing a test automation strategy.
  • Maintenance: APIs change frequently, and maintaining and updating test scripts to reflect these changes is a time-consuming and error-prone task. API test scripts need to be version-controlled and carefully managed to ensure they remain up-to-date. Scalability: An effective API test automation strategy requires a scalable testing
  • Scalability: An effective API test automation strategy requires a scalable testing infrastructure that can support different loads and stress levels. Teams must take this into account when creating the test environment and provisioning resources.
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Why use Postman for API test automation?

The Postman API Platform offers several tools that enable teams to effectively automate their API test suites. With Postman, you can:

  • Create and automate test suites: Postman's code snippet library enables users to write tests for every request in a collection, which can be chained together to create test suites that validate complex workflows. Tests can be executed manually, or they can be scheduled to automatically run on Postman's cloud infrastructure at specific times or frequencies. Teams can also choose to receive email notifications if tests fail.
  • Execute API tests in CI/CD pipelines:Teams can use Newman or the Postman CLI to automate test executions within their CI/CD pipeline. This helps ensure backwards compatibility by safeguarding the production environment from breaking changes. Results will be visible within the CI tool, as well as within Postman.
  • Debug automated test failures: Users can view the results of automated runs from within the Postman platform. Test runs can be filtered by their result, and they also include the relevant console logs, which help teams understand why an assertion failed. Any problematic request can then be rerun locally with the same environment file, which enables teams to reproduce the failure, inspect the header or body, and identify the cause of the issue.
  • Visualize automated test results: Results from collection-based monitors and scheduled runs are visualized on a filterable dashboard. This enables teams to not only spot high-level testing trends, but also hone in on specific requests, execution types, and results.
  • Create a dedicated testing environment: Postman lets users store values in variables at the environment level, which can be used in any request's URL, headers, and body. This enables users to run automated API tests in a dedicated testing environment before deploying code to production.
  • Collaboratively build and maintain test suites: Postman's collaboration features, such as commenting and version control, allow teams to work together in a single platform to create API tests that are effective, well-documented, and up-to-date. They can also easily share test results with one another and debug failures together.

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