Azure Functions (AF) 3.0/.NET 5.0/XUnit Unit Testing - Compilation Errors (C#) - unit-testing

Question

I am trying to adapt the Microsoft example for AF 3.0/.NET Core 3.1/xUnit (see Strategies for testing your code in Azure Functions) to work with AF 3.0/.NET 5.0/xUnit. However, I am running into compilation issues.
The Azure Function is a simple HTTP Trigger (GET only), ExportFuncApp.csproj file is as follows:
<Project Sdk="Microsoft.NET.Sdk">
<PropertyGroup>
<TargetFramework>net5.0</TargetFramework>
<AzureFunctionsVersion>v3</AzureFunctionsVersion>
<OutputType>Exe</OutputType>
</PropertyGroup>
<ItemGroup>
<PackageReference Include="Microsoft.Azure.Functions.Worker.Extensions.Http" Version="3.0.12" />
<PackageReference Include="Microsoft.Azure.Functions.Worker.Sdk" Version="1.2.0" OutputItemType="Analyzer" />
<PackageReference Include="Microsoft.Azure.Functions.Worker" Version="1.5.2" />
</ItemGroup>
<ItemGroup>
<None Update="host.json">
<CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
</None>
<None Update="local.settings.json">
<CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
<CopyToPublishDirectory>Never</CopyToPublishDirectory>
</None>
</ItemGroup>
</Project>
The ExportFunc.cs file is as follows:
using System.Net;
using Microsoft.Azure.Functions.Worker;
using Microsoft.Azure.Functions.Worker.Http;
using Microsoft.Extensions.Logging;
namespace ExportFuncApp
{
public class ExportFunc
{
[Function(nameof(ExportFunc))]
public static HttpResponseData Run([HttpTrigger(AuthorizationLevel.Function, "get")] HttpRequestData req,
FunctionContext executionContext)
{
var logger = executionContext.GetLogger("ExportFunc");
logger.LogInformation("C# HTTP trigger function processed a request.");
var response = req.CreateResponse(HttpStatusCode.OK);
response.Headers.Add("Content-Type", "text/plain; charset=utf-8");
response.WriteString("Welcome to Azure Functions!");
return response;
}
}
}
Nothing special there. However, XUnit tests provided by Microsoft (.NET Core 3.1) are not really applicable to .NET 5.0. There was a StackOverflow article on the subject: Testing an Azure Function in .NET 5. 4 solutions were given in the article and all of them have compile issues. The first solution given was (ExportFuncUnitTests2.cs):
using Xunit;
using ExportFuncApp;
using System.Threading.Tasks;
using System.IO;
using System.Text;
using Moq;
using Microsoft.Azure.Functions.Worker;
using System.Net;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using Microsoft.Azure.Functions.Worker.Http;
namespace ExportFuncAppUnitTestsXunit
{
public class ExportFuncUnitTests2
{
[Fact]
public async Task Http_trigger_should_return_known_string()
{
var serviceCollection = new ServiceCollection();
serviceCollection.AddScoped<ILoggerFactory, LoggerFactory>();
var serviceProvider = serviceCollection.BuildServiceProvider();
var context = new Mock<FunctionContext>();
context.SetupProperty(c => c.InstanceServices, serviceProvider);
var byteArray = Encoding.ASCII.GetBytes("test");
var bodyStream = new MemoryStream(byteArray);
var request = new Mock<HttpRequestData>(context.Object);
request.Setup(r => r.Body).Returns(bodyStream);
request.Setup(r => r.CreateResponse()).Returns(() =>
{
var response = new Mock<HttpResponseData>(context.Object);
response.SetupProperty(r => r.Headers, new HttpHeadersCollection());
response.SetupProperty(r => r.StatusCode);
response.SetupProperty(r => r.Body, new MemoryStream());
return response.Object;
});
var result = await ExportFunc.Run(request.Object, context.Object);
result.HttpResponse.Body.Seek(0, SeekOrigin.Begin);
// Assert
var reader = new StreamReader(result.HttpResponse.Body);
var responseBody = await reader.ReadToEndAsync();
Assert.NotNull(result);
Assert.Equal(HttpStatusCode.OK, result.HttpResponse.StatusCode);
Assert.Equal("Hello test", responseBody);
}
}
}
This results in a compilation error in ExportFuncUnitTests2.cs:
CS1061 'HttpResponseData' does not contain a definition for 'GetAwaiter' and no accessible extension method 'GetAwaiter' accepting a first argument of type 'HttpResponseData' could be found (are you missing a using directive or an assembly reference?)
for:
var result = await ExportFunc.Run(request.Object, context.Object);
The second solution given in the article involves FakeHttpRequestData.cs:
using System;
using System.Collections.Generic;
using Microsoft.Azure.Functions.Worker.Http;
using Microsoft.Azure.Functions.Worker;
using System.IO;
using System.Security.Claims;
namespace ExportFuncAppUnitTestsXunit
{
class FakeHttpRequestData : HttpRequestData
{
public FakeHttpRequestData(FunctionContext functionContext, Uri url, Stream body = null) : base(functionContext)
{
Url = url;
Body = body ?? new MemoryStream();
}
public override Stream Body { get; } = new MemoryStream();
public override HttpHeadersCollection Headers { get; } = new HttpHeadersCollection();
public override IReadOnlyCollection<IHttpCookie> Cookies { get; }
public override Uri Url { get; }
public override IEnumerable<ClaimsIdentity> Identities { get; }
public override string Method { get; }
public override HttpResponseData CreateResponse()
{
return new FakeHttpResponseData(FunctionContext);
}
}
}
and, FakeHttpResponseData.cs:
using Microsoft.Azure.Functions.Worker.Http;
using Microsoft.Azure.Functions.Worker;
using System.Net;
using System.IO;
namespace ExportFuncAppUnitTestsXunit
{
class FakeHttpResponseData : HttpResponseData
{
public FakeHttpResponseData(FunctionContext functionContext) : base(functionContext)
{
}
public override HttpStatusCode StatusCode { get; set; }
public override HttpHeadersCollection Headers { get; set; } = new HttpHeadersCollection();
public override Stream Body { get; set; } = new MemoryStream();
public override HttpCookies Cookies { get; }
}
}
And the test is (ExportFuncUnitTests2.cs):
using Xunit;
using ExportFuncApp;
using System.Threading.Tasks;
using System.IO;
using System.Text;
using Moq;
using Microsoft.Azure.Functions.Worker;
using System;
using System.Net;
using Microsoft.Extensions.Logging.Abstractions;
namespace ExportFuncAppUnitTestsXunit
{
public class ExportFuncUnitTests2
{
[Fact]
public async Task Http_trigger_should_return_known_string()
{
// Arrange
var body = new MemoryStream(Encoding.ASCII.GetBytes("{ \"test\": true }"));
var context = new Mock<FunctionContext>();
var request = new FakeHttpRequestData(
context.Object,
new Uri("https://stackoverflow.com"),
body);
// Act
var function = new ExportFunc(new NullLogger<ExportFunc>());
var result = await function.Run(request, context);
result.HttpResponse.Body.Position = 0;
// Assert
var reader = new StreamReader(result.HttpResponse.Body);
var responseBody = await reader.ReadToEndAsync();
Assert.NotNull(result);
Assert.Equal(HttpStatusCode.OK, result.HttpResponse.StatusCode);
Assert.Equal("Hello test", responseBody);
}
}
}
The ExportFuncUnitTests2.cs has the following compilation errors:
CS1729 'ExportFunc' does not contain a constructor that takes 1 arguments
for:
var function = new ExportFunc(new NullLogger<ExportFunc>());
and
CS1503 Argument 2: cannot convert from 'Moq.Mock<Microsoft.Azure.Functions.Worker.FunctionContext>' to 'Microsoft.Azure.Functions.Worker.FunctionContext'
for:
var result = await function.Run(request, context);
I the article Guide for running C# Azure Functions in an isolated process was somewhat useful but no help in terms of unit testing. Maybe I am missing the point. Since there is no examples/documentation on how to do unit testing for AF 3.0 with .NET 5.0 from Microsoft then I should not be trying to do that?
Any pointers will be greatly appreciated. Thanks!

Answer 1

Your Run() function in ExportFunc is not awaitable. Therefore, you should replace the line:
var result = await function.Run(request, context)
with:
var result = function.Run(request, context).
If you want to test an awaitable function (i.e., async Run()), then you'd call it from your Unit Test with await.