Using a custom extension to the Nancy test harness to be able to add multipart/form-data encoded data into the request

gistfile1.txt

[Fact]
public void Should_add_multipart_formdata_encoded_files_to_request_filestream()
{
    // Given
    var stream = 
        CreateFakeFileStream("This is the contents of a file");

    var multipart = new BrowserContextMultipartFormData(x => {
        x.AddFile("foo", "foo.txt", "text/plain", stream);
    });
            
    // When
    var context = browser.Get("/", (with) => {
        with.HttpRequest();
        with.MultiPartFormData(multipart);
    }); 

    // Then
    context.Request.Files.ShouldHaveCount(1);
    context.Request.Files.First().ContentType.ShouldEqual("text/plain");
    context.Request.Files.First().Name.ShouldEqual("foo.txt");
    context.Request.Files.First().Value.AsString().ShouldEqual("This is the contents of a file");
}