How to instantiate an instance of FormFile in C# without Moq?

Question

I want to test a function that attaches files to documents in a RavenDB database with an integration test. For this, I need an instance of IFormFile.

Obviously, I can't instantiate from an interface so I tried to instantiate an instance of FormFile which inherits from the IFormFile interface.

using (var stream = File.OpenRead("placeholder.pdf"))
{
    var file = new FormFile(stream, 0, stream.Length, null, Path.GetFileName(stream.Name))
    {
        ContentType = "application.pdf"
    };
}

But this throws the following error:

System.NullReferenceException: Object reference not set to an instance of an object.
   at Microsoft.AspNetCore.Http.Internal.FormFile.set_ContentType(String value)

When I remove the ContentType = "application.pdf" from the code it allows me to instantiate a new instance but without a ContentType.

How do I instantiate an instance of FormFile with the ContentType and without the Moq framework?

"without the Moq-framework" By using another framework? Honestly: why don´t you want to use moq in your unit-test-environment? It´s designed exactly for this purpose. — MakePeaceGreatAgain, Aug 06 '18 at 09:54
It is pretty low-level, it wants you to set the Headers property first. https://learn.microsoft.com/en-us/dotnet/api/microsoft.aspnetcore.http.headerdictionary?view=aspnetcore-2.1 — Hans Passant, Aug 06 '18 at 10:04

Devator · Accepted Answer · 2020-03-18T19:29:26.057

95

Thanks to Hans his comment, the actual answer is:

using (var stream = File.OpenRead("placeholder.pdf"))
{
    var file = new FormFile(stream, 0, stream.Length, null, Path.GetFileName(stream.Name))
    {
        Headers = new HeaderDictionary(),
        ContentType = "application/pdf"
    };
}

edited Mar 18 '20 at 19:29

answered Oct 12 '18 at 15:34

Devator

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12

I just need to add that the fact that this is the answer, and that ContentType has both Get and Set NullReferenceExceptions makes FormFile a garbage object and pattern. – Captain Prinny Oct 10 '19 at 20:47
i have been searching for this. İt is working, thank you ! – Mesut Başaran Jan 27 '21 at 11:41
1

Worked, thanks! Not clear from the exception though – Eldar Scott Apr 12 '21 at 05:58
Not working for me, don't understand why – bgman May 27 '22 at 15:53
2

Ok, didn't set the Headers property, once set no more Exception – bgman May 29 '22 at 15:37
How can we set a custom size on a formfile? – Ali.Rashidi Jul 26 '23 at 06:34

How to instantiate an instance of FormFile in C# without Moq?

1 Answers1

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