CODEWITHSUNDEEP
unit-testingazureazure-functionsasp.net-core-webapi
EricDBoyd
EricDBoyd

Reputation: 61

Unit Testing Azure Functions with HttpRequestMessage

I'm running into a few issues when trying to unit test HTTP Trigger Azure Functions in Visual Studio. I've created a GitHub repo (https://github.com/ericdboyd/TestingAzureFunctions) with an example solution that contains both an Azure Function project and a Unit Test project that demonstrates the issues.

First, when I bring in Microsoft.AspNet.WebApi.Core it creates a conflict between System.Web.Http and Microsoft.AspNetCore.Mvc.WebApiCompatShim when trying to use IContentNegotiator. The only way around that was to alias WebApiCompatShim in the csproj file for the test project using the following:

<Target Name="ChangeAliasesOfStrongNameAssemblies" BeforeTargets="FindReferenceAssembliesForReferences;ResolveReferences">
<ItemGroup>
  <ReferencePath Condition="'%(FileName)' == 'Microsoft.AspNetCore.Mvc.WebApiCompatShim'">
    <Aliases>webapicompatshim</Aliases>
  </ReferencePath>
</ItemGroup>

Once I got past that error, I run into this issue which I haven't been able to get past. Using the HttpRequestMessage.CreateResponse extension method to return a response in the Azure Function, I get "No service for type 'System.Net.Http.Formatting.IContentNegotiator' has been registered." when I try to test it. I have tried to build a HttpRequestMessage that I think should work with that extension method using the following code which can also be found in the GitHub repo, but it fails, and I have worked on trying to get past this for several hours now.

IServiceCollection services = new ServiceCollection();
services.AddOptions();
services.AddSingleton(typeof(IContentNegotiator), typeof(DefaultContentNegotiator));
IServiceProvider serviceProvider = services.BuildServiceProvider();

var httpContext = new DefaultHttpContext {RequestServices = serviceProvider};

var httpConfiguration = new HttpConfiguration();

HttpRequestMessage request = new HttpRequestMessage
{
    Method = HttpMethod.Post,
    RequestUri = new Uri(url),
    Content = new StringContent(content, Encoding.UTF8, "application/json"),
    Properties =
    {
        { HttpPropertyKeys.HttpConfigurationKey, httpConfiguration },
        { nameof(HttpContext), httpContext} 
    }
};

If I don't use that CreateResponse extension method, and just create HttpResponseMessage objects, it works fine.

Just to set some additional context, I know this is not the best way to unit test the code being executed by the Azure Function. I'm unit testing that code much more granularly. But I want to be able to unit test the Azure Function that is performing the mapping between the http request and response to that logic.

There are two Azure Functions and two unit tests in the GitHub repo, one set with the extension method, one without to demonstrate the issue. But everything else is the same.

Upvotes: 4

Views: 2216

Answers (2)

Siri
Siri

Reputation: 207

Specify the jsonformatter while responding as below

req.CreateResponse(HttpStatusCode.OK, $"Hello, {name}", new JsonMediaTypeFormatter())

Upvotes: 0

Mikhail Shilkov
Mikhail Shilkov

Reputation: 35134

Not a direct answer to your problem, but it should help you go forward.

You are using Azure Functions v2 - .NET Standard version. This version is currently in beta, so it's a bit shady territory: the documentation is missing and some issues exist.

In V2 you are advised to use HttpRequest class and IActionResult instead of 'classic' HttpRequestMessage and HttpResponseMessage. The default template has a signature like this:

public static IActionResult Run(
    [HttpTrigger(AuthorizationLevel.Function, "get")] HttpRequest req, TraceWriter log)

This should enable you to get rid of your shim and to unit test the functions similar to ASP.NET Core way.

Upvotes: 1

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