Mock a REST API - Part 3

Configuring an API to return different HTTP Status Codes

In the previous tutorial we created a mock REST API capable of returning multiple responses with the same HTTP Status Code.
In this tutorial we will be creating a mock REST API that will return responses with different HTTP Status Codes.

You can also watch the step-by-step instructions in the video below

Step 1: Create a new HTTP GET API endpoint

Select GET from the HTTP Method drop-down-list
Enter the desired path in the in API Path textbox, we will enter /api/v1/product/info in the API Path text box for demonstration purposes

Define mock API endpoint path and http method type

Step 2: Define the default response of the new GET API

Scroll down to HTTP Response section
We will enter 200 in the Response Code textbox, but you can enter any code that fits your need, this is only for demonstration purposes
We will enter text/plain in the Response Content-Type textbox, but you can enter a different return content-type.
We will enter Hello World in the Response Body textarea

Provide the http status code, response content-type value and response body contents of the mock API endpoint

Step 3: Add additional responses to the new API for enabling response simulation

Scroll down to Alternate HTTP Responses section
We will enter 201 in the Response Code textbox
Let's enter text/html in the Response Content-Type textbox
Let's enter the html shown below in the Response Body textarea

<p><b>Product Info</b> - This is a mock REST API demo by Api On Cloud (https://www.apioncloud.com)</p>

Click on the Save/Add Alternate Response button to save this response

Save the additional mock API response after entering response status code, content-type and response body

We will add a few more responses in the same way

We will enter 202 in the Response Code textbox
Let's enter application/json in the Response Content-Type textbox
Let's enter the json shown below in the Response Body textarea

{"message": "Product Info API", "statusCode": 202 }

Click on the Save/Add Alternate Response button to save this response

Defining an additional response that the mock API should be able to return in simulation mode.

Now let's define a response that returns HTTP Status Code 404

We will enter 404 in the Response Code textbox
Let's enter text/plain in the Response Content-Type textbox
Let's enter the text shown below in the Response Body textarea

Oops! The API endpoint you called does not exist

Click on the Save/Add Alternate Response button to save this response

Associate 404 Page Not Found response with the mock API Endpoint

Nod add a response that returns HTTP Status Code 500

We will enter 500 in the Response Code textbox
Let's enter application/json in the Response Content-Type textbox
Let's enter the text shown below in the Response Body textarea

{"message": "Product Info API", "statusCode": 500, "description": "The API Server has encountered an internal error"}

Click on the Save/Add Alternate Response button to save this response

Adding HTTP 500 Internal Server Error as a response to the mock API endpoint

Step 4: Save the API and enable response simulation

Scroll to the top of the page and click on the Publish API button. This will save the newly defined HTTP GET API

Pressing a button to save and publish the new mock API endpoint

To make this API return all the alternate responses we have added in Step 3, we need to run this API in simulation mode. To run the api in simulation mode, press the Simulation Mode: Off button to switch-on response simulation

Pressing the simulation button to enable API simulation mode

Step 5: Test the new mock API Endpoint

You can easily test the newly created mock REST API by switching to the built-in API Tester
Click on the Test API Endpoint button will take you the built-in API Tester

On the API Tester screen, all the required HTTP Request fields will be already populated.
Clicking on the Call API will call the new mock API and the response of the API will be displayed below the HTTP Response section.

Calling the mock API by pressing the Call API button in testing mode

If you enabled Simulation before launching the API Tester then the mock API will return one of the alternate responses you defined at the time of API creation. You can test response simulation by pressing the Call API button more than once.

We now have a mock API endpoint capable of returning different responses when simulation mode is enabled.