HttpClient from WebApplicationFactory returns "415 Unsupported Media Type" on HttpMethod.PATCH

[lobodava]

When try to use HttpClient from WebApplicationFactory (Microsoft.AspNetCore.Mvc.Testing, Version=5.0.9.0) with xUnit, the PATCH http method always returns "415 Unsupported Media Type" status code.

For example, here is the ASP.NET Core 5.0 Web Api Contoller:

public class HomeController : ControllerBase
{
    [HttpPatch("entities")]
    public async Task EntitiesPartialUpdate(Entity[] entities)
   {
	await EntitiesPartialUpdate(entities);
   }
}

And here is the xUnit test to call the above http method:

private readonly HttpClient Client;

public MyTests(WebApplicationFactory<Startup> fixture)
{
    Client = fixture.CreateClient();
}

private async Task PatchAsync<T>(string url, T data)
{
    var dataJson = JsonSerializer.Serialize(data);
    var requestBody = new StringContent(dataJson, Encoding.UTF8, "application/json");
    var request = new HttpRequestMessage(HttpMethod.Patch, url) { Content = requestBody };
    request.Headers.Authorization = new AuthenticationHeaderValue("Bearer", this.ApiKey);
    
    var response = await Client.SendAsync(request);

    if (response.StatusCode ==  HttpStatusCode.UnsupportedMediaType)
    {
        // always get here
    }
}

If to call the Patch controller methods from regular http client like Swagger or Postman, this Patch methods work well and without any bug, however calling these Patch methods from HttpClient withing the xUnit tests fail in any configuration of requests. Client.SendAsync and Client.PatchAsync fail identically.

Calling of the other http methods like Post, Get, Put within the xUnit test succeed as well.

• ASP.NET Core version: 5.0
• The IDE : Microsoft Visual Studio Community 2019, Version 16.11.1

We've moved this issue to the Backlog milestone. This means that it is not going to be worked on for the coming release. We will reassess the backlog following the current release and consider this item at that time. To learn more about our issue management process and to have better expectation regarding different types of issues you can read our Triage Process.

[kristofke]

I have the same behavior in my own code.
After a deeper look, I might have seen a possible issue in the code of Microsoft.AspNetCore.Mvc.Testing.

Because we're using authorization, the HttpClient is making a redirect.
(By default, the AllowAutoRedirect is set to true on this client.)

This will eventually be handled by the RedirectHandler.
Inside this handler, it checks if the original request content had a body. If so, it'll duplicate the request content.
However, as you can see here, it'll only check for a body when the request method was either post or put.

This will lead to the content being null when making a patch call (after the redirect).
When the content/body of the request is null, it can't figure out what the media type should be and eventually results in a UnsupportedMediaType.

Can someone confirm if this might actually be the problem?
Maybe the HasBody method in the RedirectHandler is intentionally only allowing post and put methods?

[kristofke]

I've been able to write some code. Hopefully my changes will make things clearer.

At first, I've written some tests for the post, put and patch method.
Making an HTTP request with some body, that performs a redirect, will work for the post and put methods.
However, this won't work when the method is a patch.

After making my change inside the HasBody method of the RedirectHandler, the test performing a patch request succeeded.
All other tests inside Mvc still seem to work as well.

I didn't want to make a PR yet, because I'm not sure if the HasBody method was designed specifically for post/put requests.
Can someone confirm if my changes are allowed?
Maybe @javiercn or @rafikiassumani-msft?

Thanks.

[geh24]

While developing a .NET Core API-Project i came across the exact same problem.
Many thankt to @kristofke who identified the origin of the problem using Patch-Requests
from a HTTPClient created by a WebApplicationFactory.

At first i thought using his changes but than i found another, easier way to
handle this problem by avoiding the https-redirect.

WebApplicationFactoryClientOptions opt = new WebApplicationFactoryClientOptions();
opt.BaseAddress = new Uri("https://localhost");
_client = _factory.CreateClient( opt);

Directing the BaseAddress to https, no Redirect occurs and the PatchAsync works fine with Json-Content and Authorization

Thanks

[marcel-smits]

Is there any update on this ?
I am currently facing the same issue and using Https is not an option

[nicolaslepinayqc]

Hi there,

I get the same error using POST with plain text context:
`

        // Arrange
        var request = new StringContent(PARAMETRES, Encoding.UTF8, "text/plain");
        var response = await client.PostAsync(ENDPOINT, request);            
        // Assert
        response.StatusCode.Should().Be(HttpStatusCode.OK);

`

[SteevenR]

Hello, we are facing the same issue.
Do you have any planned fix ?

[patchua]

Hi, I have very same problem but with DELETE request type with Body.
Can we fix HasBody to include Patch and Delete?