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Simulating Slow APIs During Development with Beeceptor

Simulating API latency is a vital step in assessing how your application performs under different network conditions. A slow timeline allows you to understand how your application displays loading indicators, manages user interactions, and recovers from errors or timeouts. Testing across these scenarios is key to guaranteeing a seamless and satisfying user experience for users on various networks.

This guide explores using Beeceptor, a hosted HTTP Proxy tool, to simulate API latency. Let's first understand how this method benefits you in quality assurance.

Why Simulating API Latency?​

As a quality assurance engineer or SDET, here are various scenarios where testing with slow APIs can be beneficial.

  • Evaluating web app performance on slower networks: Test how your application behaves on networks with limited bandwidth, such as 3G or 2G networks. This is crucial for ensuring a good user experience in regions with slower internet connections.
  • Understanding app behavior under increased API response times: Determine how your application copes when APIs take longer to respond. This is particularly important for apps that rely heavily on real-time data. Does any part of the user-interface hangs?
  • Identifying race conditions caused by asynchronous loading of resources: Race conditions occur due to asynchronous loading of resources. These API delays gives enough time to uncover race conditions in shared resources or variables.
  • Testing Third-Party API Dependencies: Evaluate how delays in third-party APIs affect your application, which is crucial for apps that integrate external services.
  • Impact of external resource loading speeds on your application: Analyze how the loading time of external resources, such as third-party APIs or content delivery networks, impacts your application's performance.

Setting Up Beeceptor for API Latency Simulation​

The following setup enables you to tailor Beeceptor for introducing specific delays on chosen request paths. The advantage of utilizing Beeceptor lies in its flexibility; it allows you to implement varied delays for different request paths or even based on user tokens.

  1. Creating a New Endpoint

    Begin by visiting the Beeceptor website. Here, you'll need to create a new endpoint. This endpoint will serve as a crucial component in simulating the API latency. Think of it as a middleman between your application and the actual API.

  2. Configuring Proxy Settings

    Once your endpoint is created, the next step is to set up a proxy configuration. This involves entering the base URL of your original API into Beeceptor. This setup ensures that when your application sends requests to the Beeceptor endpoint, Beeceptor will automatically route these requests to your original API, following the same requested path.

  3. Integrating Beeceptor Endpoint in Your Application

    Replace the API endpoint in your application with the Beeceptor endpoint URL. This change means that all the requests from your application, which were previously directed to your original API, will now go through Beeceptor first.

  4. Testing the Setup

    After integrating the Beeceptor endpoint, send a request from your application. This request will pass through Beeceptor before reaching your actual API. You can then view and inspect this request on the Beeceptor dashboard.

  5. Creating a Mocking Rule for Additional Delay

    Now, it's time to simulate the latency. In the Beeceptor dashboard, create a new mocking rule for your endpoint. Set this rule to add an additional delay to the response – for example, 2 seconds. This delay is added on top of the response time of your original API. The response from your original API will be processed as usual, but Beeceptor will introduce an additional delay before the response reaches your application.