[C#] DefaultHttpContext.Response is null, why?

Question

Hi :)
I have been learning how to create an api and I did an Global Exceptions Handler. After that i have done unit tests for this. I did this (not copy-paste) but i wrote line by line how it was on this website
http://anthonygiretti.com/2018/09/04/asp-net-core-2-1-middlewares-part2-unit-test-a-custom-middleware/
and my context.Response.Body is null because context.Response is null. I tried to find sth in the internet but i couldn't :( could somebody help me?

private DefaultHttpContext GetHttpContext()
{
var context = new DefaultHttpContext();
context.Response.Body = new MemoryStream();
return context;
}
[Fact]
public async void A()
{
//Arrange
var middleware = new ExceptionMiddleware((HttpContext innerHttpContext) =>
{
throw new FakeApiException();
});
var context = GetHttpContext();
//Act
await middleware.InvokeAsync(context);
context.Response.Body.Seek(0, SeekOrigin.Begin);
var reader = new StreamReader(context.Response.Body);
string streamText = await reader.ReadToEndAsync();
ErrorDetails objResponse = JsonConvert.DeserializeObject<ErrorDetails>(streamText);
//Assert
Assert.Equal("Internal Server Error from the custom middleware", objResponse.Message);
}

I have been larning english and can you tell me, where (if they are exists) mistakes? Thanks in advance :)

Answer 1

Can you show use the code ?

Answer 2

Ok.

I do not understand a whole lot.

But where do you call this method ?
And which website are you reading ?

Answer 3

http://anthonygiretti.com/2018/09/04/asp-net-core-2-1-middlewares-part2-unit-test-a-custom-middleware/ this website, and in GetHttpContext there is context.Response.Body = new MemoryStream(); and this Response is null

Answer 4

context.Response.Body = new MemoryStream();

new MemoryStream() creates a empty MemoryStream so it is logical that this results in "null"

So where is the memorystream filled ?

Using google I found this link does it help you ?

https://stackoverflow.com/questions/56225883/how-to-fix-defaulthttpcontext-response-throwing-nullreferenceexception-in-c-shar

Answer 5

It my question but on stackoverflow hahaha. You dont understand... context.Response is null

Answer 6

Hihi. Sorry I can't help you.

Answer 7

Why

Answer 8

Because there is to little information in your question.
You english is understandable though.

The code snippet is to small to understand where the data should come from

I do not mean from which site you got the example but I meant the site where you want to read data from.

I am a c# specialist but I do not use asp.net, so I was just guessing based on common programmers knowledge.

Answer 9

It is unit test

Answer 10

But where is the input parameter of your unit test ?

Answer 11

Input parameter? What do you mean? Had you read this article or not?

Answer 12

I will admit, I did not read the article first.

So I did and I understood. That DefaultHttpContext does not need a site. It gives you some default data so you can test without having a link.

My next guess is the method name GetHttpContext is already in use.

Your method :
private DefaultHttpContext GetHttpContext()

ASP.net method
GetHttpContext is a method in Microsoft.AspNetCore.SignalR
https://docs.microsoft.com/en-us/dotnet/api/microsoft.aspnetcore.signalr.gethttpcontextextensions.gethttpcontext?view=aspnetcore-2.2
This method returns null if not associoated with HTTPRequest

So I think the compiler confused and executes the ASP.net method.

Try
private DefaultHttpContext MyGetHttpContext()
and
var context = MyGetHttpContext();

Unfortunately I have not been able to test it.
Hope it works.

Answer 13

Still the same :/ DefaultHttpContext was created for testing instead of HttpContext besauce this second class is almost impossible to testing. I did what you wote, I was interested when Repsonse is not null and.... I expanded the context in debug mode and EVERYTHING is null, any property :/ I'm using .Net Core 3 preview 5, maybe this is a reason why this class isn't work properly?