Mock and Unit Test ASP.NET Middleware Component

In this article, we shall see how to Mock and Unit Test ASP.NET Core Middleware component.

As we know Middleware is a component that is used in the application pipeline to handle requests and responses which can also help perform pre and post-operation within the API pipeline.

While you add these customizations in the form pre or post-request or response, you may want to Unit Test these components in the robust code.

Today in this article, we will cover below aspects,

Getting started

I already have a sample Middleware component as below which adds a custom header(x-thecode-buzz) to the HTTP responses.

Unit Under Test as below,

We shall be using the AAA (Arrange- Act-Assert) pattern.

Mock HTTPContext using DefaultHttpContext

Please use the DefaultHttpContext object to set up a mock version of the HttpContext in the controller.

 var httpContext = new DefaultHttpContext();

Mocking IHttpResponseFeature

Mocking IHttpResponseFeature can be achieved as below.

 


            var feature = new Mock<IHttpResponseFeature>();
            feature.Setup(option => option.HasStarted).Returns(true);



            

Set up the mocked IHttpResponseFeature to the given HttpContext as below,

 
 


httpContext.Features.Set<IHttpResponseFeature>(feature.Object);
 RequestDelegate next = async (HttpContext hc) =>
            {
                await Task.CompletedTask;
            };

Now let’s invoke the method with mocked delegates and mocked HttpResponseFeature.

            


//Act
            GlobalHeaderMiddleware headerMiddleware = new GlobalHeaderMiddleware(next);
            await headerMiddleware.InvokeAsync(httpContext);
            var response = httpContext.Response;

That’s All !!

Happy Coding!

Do you have any comments or ideas or any better suggestions to share?

Please sound off your comments below.

Happy Coding !!

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