API Mocking

Edit online

webMethods API Gateway supports mocking ability for both REST and SOAP APIs. This example explains how you can use the mocking functions for a REST API. In this example, you enable mocking for a REST API PetStore, modify the mocking details, and verify the mocked response as per the configured mocked response.

About this task

During API development, you might have the following concerns:

  • How can you test your API while your native API is still under development?
  • How can you continuously test your APIs on an ongoing basis, for example, CI-CD pipelines, without any external dependencies, especially under circumstances where the backend is subjected to downtimes or requires access credentials that are changed frequently?

Mocking is the capability that helps you accelerate your development lifecycles by reducing the dependencies between your development teams, especially the API consumer, and the backend. API Gateway helps mock an API. The mocked API provides realistic native API responses to requests. You can mock an API by simulating the native API, by using the API mocking capability in webMethods API Gateway. For example, if you have an API without a native implementation, you can mock that API. When the API is started, the mock API server returns the mocked response to the client that started the API.

With webMethods API Gateway, you can modify the default-mocked response and configure it as needed. You can customize it for each combination of resource, operation, status code, and content type based on the examples and schemas specified in the API. In addition, you can add a condition to the operation in the resource.

The following figure shows the high-level steps for mocking an API.

api mocking

Procedure

  1. Enable API mocking
    1. Open the menu options and select APIs.
    2. Select the Petstore API.
    3. Click API Details tab.
    4. Ensure that the API is in Deactivate state. If the API is not in a deactivated state, click Deactivate and click Yes to confirm.
    5. Click the vertical ellipsis icon icon and select Enable Mocking.
  2. Erich mocking.
    1. Select APIs > Petstore.
    2. Click Edit > API mocking.
    3. Select /pet/findByStatus resource from the list of resources.
    4. Add a response of your own.
      1. Click Add Response and select the Status code. Choose 200 from the menu.
      2. Click Add to add it to the existing code list.
    5. In certain instances, the mock API server sends a mocked response based on certain conditions and parameters. You can add a condition to the operation by doing the following steps.
      1. Click Add Conditions and specify the Condition name, for example, SuccessNoContent.
      2. Select the type of Condition parameter to which the condition must be applied. You can choose one of the following options: Body, Header, or Query Parameter.
      3. Specify the Key value, which can be a JSON path or XML path.
      4. Add a value to your condition.
      5. Select a status code, say 204, from the list.
        Note: To use the code 506, you must enable the property Send native provider fault in the section Administration > General > API fault. The query parameter must be set to expectStatusCode, while you call an API to have correct mock responses for status codes 100 and 202.
    6. If you want to add a response header for the API, perform the following steps.
      1. Select Add Response Header and specify the Header key as MockedResponse and the Header value as True. These values are contained in the HTTP response.
      2. Click Add to add the header value to the list of response headers.
    7. To add a content-type to the selected status code, perform the following steps.
      1. Click Add content-type and select a content type value from the list.
      2. Specify a mock response payload for the selected content-type value.
      3. Select Add to save your selection. You can add multiple content-types.
    8. Click Save to save your changes. You can choose multiple options to mock an API. For more information about different ways to mock an API, see API mocking.
  3. Validate the mocked response.
    1. Activate the Petstore API by clicking the Activate.
    2. Navigate to the Technical information tab and copy the endpoint link under Gateway local host.
    3. Open Postman.
    4. Open a new tab and paste this link under Untitled request.
    5. Click Send to get the mocked response.
    6. To disable mocking, click Deactivate to deactivate the API.
    7. Click ellipsis and select Disable mocking.
    8. Click Activate to activate the API.
    9. Go to Postman and click Send. You now see the actual response of the Petstore API.