AspNetCore.ApplicationPipeline is a package to help ASP.Net Core developers manage application pipeline for HTTP requests programmatically.

Developers have to hard-code the application pipeline in Configure method in Startup class. The pipelines built with this approach stop developers from adding/removing middlewares (steps) to/from the pipeline on-demand.

Changing application pipeline programmatically is required for some testing scenarios such as well as developing frameworks.

First, configure and add the pipeline to the service collection using AddApplicationPipeline method. For instance, the following code shows how to create, configure, and add a HttpPipeline to the IServiceCollection. As you can see, this pipeline has different steps, and each step is created using concrete Classes, Expressions, or Actions.

public void ConfigureServices(IServiceCollection services)
{
    //...

    services.AddApplicationPipeline(pipeline =>
    {
        pipeline
            .Add<DeveloperExceptionPageStep>()
            .Add(app => app.UseHttpsRedirection())
            .Add("routing-step", app => app.UseRouting())
            .Add<SecurityStep>()
            .Add<EndpointsStep>();
    });

    //...
}

Second, use the pipeline using UseApplicationPipeline method in Configure method in Startup class as the following:

public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
    app.UseApplicationPipeline();
}

Now, you can add/remove pipeline steps on-demand. For instance, the following shows how to add a custom step named HttpTransactionRecorderStep just before step EndpointsStep for integration test.

For more details, please have a look at the sample and its test projects.

public class TransactionIdTests : IClassFixture<WebApplicationFactory<Startup>>
{
   private readonly WebApplicationFactory<Startup> _factory;

   public TransactionIdTests(WebApplicationFactory<Startup> factory)
   {
       _factory = factory.WithWebHostBuilder(host =>
           host.ConfigureTestServices(services =>
           {
               services
                   .AddApplicationPipeline(pipeline =>
                   {
                       pipeline.AddBefore<EndpointsStep, HttpTransactionRecorderStep>();
                   });
               //...
           }));
   }

   //...

.Net Core version 3.1 is the only supported version.

TBA...