Overview
Snapshot tests help you verify if your API responses adhere to the structure/value defined in a ‘snapshot’. Using this template, you can create snapshots, test your API responses against them, and fish out any unexpected responses.
What is snapshot testing?
Snapshot testing is a technique in API development that involves capturing the current state of API responses (snapshots) and then comparing subsequent API responses against these snapshots. It helps ensure that the API responses remain consistent over time and that no unexpected changes occur.
What are the benefits of snapshot testing?
Here are three main advantages of performing snapshot testing:
Ensuring consistency:
Snapshot testing helps maintain the consistency of API responses, reducing the likelihood of introducing bugs or errors during development.
Simplified test maintenance:
Since snapshots serve as a reference, they simplify the process of updating and maintaining tests when the API responses change intentionally.
Time efficiency:
Snapshot testing significantly reduces the time spent manually verifying API responses and improves the overall testing efficiency.
What does the response snapshot testing template contain?
The response snapshot testing template contains sample API requests and reusable test scripts that demonstrate the following three snapshot testing strategies:
Snapshot subset:
Verifying that the API response contains a subset of the snapshot, ensuring that any additional data is acceptable.
Exact snapshot match:
Ensuring the API response matches the exact snapshot, detecting any unexpected changes.
JSON schema comparison:
Matching the API response against the JSON Schema generated from the snapshot, validating response structure and data types.
How to use the template to perform snapshot testing?
By following the steps listed below, you can effectively perform snapshot testing using the template - Step 1. Understand the template: Familiarize yourself with the contents and purpose of the template. Read the documentation to interact with the template and get the hang of snapshot testing in Postman. Step 2. Customize the template: Customize the pre-configured requests to match your API's endpoints and specific testing requirements. Capture snapshots of the initial API responses by saving your response as an example in Postman. Step 3. Prepare for testing: Create a mock server to help with snapshot testing. Update the 'snapshotURL' variable in the collection with your mock server's URL. Step 4. Choose a snapshot strategy: Decide how you want to perform the snapshot testing based on your response structure. Step 5. Run the tests: Resend the request and check the test results in the response section's 'Test Results' tab.
Frequently Asked Questions
Who can use the response snapshot testing template?
+The response snapshot testing template can be used by anyone who is involved in API development, including:
Quality engineers
Backend developers
Fullstack developers
Frontend developers
When should you perform snapshot testing?
+Snapshot testing is a testing technique used primarily in frontend development, especially for UI components and visual elements. Here are a few scenarios in which you can perform snapshot testing:
When developing UI components (e.g., React components, Vue components), snapshot testing can ensure that changes to the component's output don't introduce unexpected visual regressions. When you refactor or change your codebase, snapshot testing can ensure that the visual output remains consistent.
It's important to note that snapshot testing is not a replacement for unit or end-to-end testing. Instead, it complements these other testing strategies, providing an additional layer of confidence in the visual aspects of your application.
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