Currently I don't see a way to unit test a retry policy if you use the time-based retry policy. retryAttempt => TimeSpan.FromSeconds(Math.Pow(retrySleepDuration, retryAttempt)), InlineData(1, HttpStatusCode.RequestTimeout), InlineData(0, HttpStatusCode.InternalServerError), GetRetryPolicy_Retries_Transient_And_NotFound_Http_Errors. How does having the Polly policy in play affect your existing unit tests? If any of your tests are missing from the window, build the test project by right-clicking its node in Solution Explorer and choosing Build or Rebuild. We do not want to loose any order because this will directly result in money loss. If you check the constructor of HttpClient you will see that it inherits and abstract class IHttpMessageHandler which can be mocked since it is an abstract class. You may want to test how your code reacts to results or faults returned by an execution through Polly. Find centralized, trusted content and collaborate around the technologies you use most. Right-click on the test project node in Solution Explorer for a pop-up menu. Define and run tests inside one or more test projects. Unexpected uint64 behaviour 0xFFFF'FFFF'FFFF'FFFF - 1 = 0? The test uses WebApplicationFactory to exercise your normal app startup in configuring the HttpClient/policy to be tested; but then pull the "test" HttpClient configuration out for a tighter unit test. HttpClient relies on the HttpMessageHandler.SendAsync method, so we can mock this method and class and pass it to the constructor or HttpClient class instance. In the Add Reference dialog, choose the project(s) you want to test. There is no need for any WebApplicationFactory, IHost, IHostedService or anything from ASP.NET. Install nuget Microsoft.Extensions.Http.Polly. If somebody changes the configuration, the test provides regression value by failing. Let us know how you get on with that - or if you can envisage ways it could be improved (I can envisage some - as ever, with trade-offs). Making statements based on opinion; back them up with references or personal experience. It is possible simply to new up a ServiceCollection; configure a named client using HttpClientFactory; get the named client back from the IServiceProvider; and test if that client uses the policy. Can it still be improved? (in response to "I cannot retrieve the HttpClient that has been configured with the Polly polly"), (to respond to the question title: "Test Polly retry polly configured via Startup.ConfigureServices() with ASP.NET Core API"). You can also explore and run the Polly-samples to see policies working individually, and in combination. I don't want to wait more than one minute in my tests. you directly to GitHub. Additionally, we want to be able to make our methods that rely on Polly unit testable. There are no ads in this search engine enabler service. Edit and build your test project or solution. From the Polly repository: Polly is a .NET resilience and transient-fault-handling library that allows developers to express policies such as Retry, Circuit Breaker, Timeout, Bulkhead Isolation, and Fallback in a fluent and thread-safe manner. If you want to know more of how to easily retry and make your application more resilient to poor and unstable network connection check articleIncrease service resilience using Polly and retry pattern in ASP.NET Core. preview if you intend to use this content. Lets work on another revision of the code to add extra retries for these scenarios: I am going to stop right here. The code is simple, it hardly needs further explanation. Upgrade to Microsoft Edge to take advantage of the latest features, security updates, and technical support. For the first case I use Moq to mock the error prone code so it returns an incorrect value. To add a new test project to an existing solution. This integration can be tested via an integration or component test. GitHub blocks most GitHub Wikis from search engines. Polly is able to wrap different policies to handle different scenarios: While this is not the way I would structure my code in a real app, I believe this is understandable and maintainable code. This means every outbound call that the named-client "test" makes would return HttpStatusCode.InternalServerError; it's a minimal example of what HttpClientInterception does, but HttpClientInterception does more, does it with much more configurability, and with a nice fluent syntax. Right-click on the failing test for a pop-up menu. This page also exists in a longer version with worked examples, How to approach unit-testing code wrapped in Polly policies depends what you are aiming to test. 2023 Jacob Duijzer. How to Implement Retry Logic in C# - Code Maze If it fails with a different exception or status code, it propagates the exception to the caller. It was just a trigger for me to write about Polly. To make sure all calls to the APIs will have a high success rate I had to implement retry mechanisms for different scenarios. Visual Studio 2017 and later (Professional and Enterprise editions) CodeLens lets you quickly see the status of a unit test without leaving the code editor. In the following example, assume MyClass has a constructor that takes a std::string. TEST_CLASS and TEST_METHOD are part of the Microsoft Native Test Framework. And, even better, a mechanism to do some retries before throwing an exception. Content Discovery initiative April 13 update: Related questions using a Review our technical responses for the 2023 Developer Survey, C# Kafka: How to Create a NetworkException Error, Unit testing internal methods in VS2017 .NET Standard library, Using Polly to retry on different Urls after failing retries. Lets say you want to check if your code was retried 3 times and then successfully completed on the final attempt. You can configure these methods on a mock policy, to return or throw faults you want to simulate. For Boost.Test, see Boost Test library: The unit test framework. Updated Integration Test method If this should be done through SystemClockor not i'm not sure, however in our scenario it's perfect for testability. Here onRetryAsync is passed a deligate inline method that just writes out a message. Create test projects in the same solution as the code you want to test. Why did DOS-based Windows require HIMEM.SYS to boot? This only tests that a mock is being called, not that the retry policy is working. How can Config be setup for Integration test within WithWebHostBuilder() in TestRetry() method if it is the correct method, and for unit test in HttpClientFactory_Polly_Policy_Test class. By clicking Sign up for GitHub, you agree to our terms of service and Testing Your Code When Using Polly | no dogma blog Has the Melford Hall manuscript poem "Whoso terms love a fire" been attributed to any poetDonne, Roe, or other? As suggested in the comments I recommend Simmy. This brings us to unit testing. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, Hi, There is a nice way to test these type of scenario using Http interceptions - using JustEat nuget, checkthis out ->. Last Modified: Mon, 23 Sep 2019 21:54:42 GMT, This page is a concise conceptual overview of different unit-testing approaches you may take with Polly. Disclaimer: this article and sample code have nothing to do with the work I did for the eCommerce website. http://www.introtorx.com/Content/v1.0.10621.0/16_TestingRx.html#TestScheduler for more information. Visual Studio 2017 and later (Professional and Enterprise), Visual Studio 2017 and later (all editions). Right-click on a test for other options, including running it in debug mode with breakpoints enabled. The basic configuration is similar for both the Microsoft and Google Test frameworks.
