Mock servers can be used to fake APIs and simulate server responses. They can serve canned responses to specific requests.
Table of Contents
- Why use a mock server?
- Create your first mock server
- Recording responses from an existing API
- Known limitations
Mock servers can be used to:
- design APIs
- prototyping
- API testing
Mock servers are useful when building frontends and the actual API does not yet exist or is under development.
Mock servers can be used in scenarios where you want to test a 3rd party, such as a payment gateway, but don't want to interact with the actual payment gateway itself.
A mock server, in this scenario, is used to isolate an external process so that tests are not run against that service.
Mock servers are also useful for evaluating how a UI will respond when 3rd party APIs fail in different ways, when it may be difficult or cumbersome to evaluate those failing cases with the APIs themselves.
Mock servers are integrated in the Postman service, and ar configurable via the Postman app.
They are CORS-enabled so that requests may be made from any domain.
Up to 1000 requests can be made per month on the free tier.
In Postman:
- click on New in the top left corner
- click Mock Server in the modal that appears
- enter endpoints and return values
- enter a name for the mock server
- click Close on the final modal
This creates a new collection in the workspace with the name of your mock server, as well as an environment of the same name as your mock server.
In order to send requests in the collection you'll need to select the matching environment.
When inspecting the request, you'll notice that each request has an example with the response entered into it during configuration.
Multiple examples can be added here, each with their own response codes and bodies. This allows one to keep mock requests for any specific resource organised under a single request in the collection.
If Postman is unable to match a request to an example, it'll return the response for the request it most closely resemsbles.
To save response from an existing API, and create a mock server from that data:
- Create a collection and request
- Make a request
- In the header of the response section click Save to save the response as an example
- Repeat for as many different responses as you want
- Save the request
- Create a mock server using the menu to the right of the collection name in the sidebar
- data in response bodies is not dynamic; different
POSTdata will get the same response - query parameters are disregarded
- a workaround for getting different response bodies is to send different request headers