C# Unit Testing

Table of contents

• NuGet packages
• Syntax
  • Given-When-Then
  • Arrange-Act-Assert
  • Moq
  • Assertions
• Collect code coverage
• Generate code coverage report

NuGet packages

• Frameworks
  • NUnit
  • xUnit
• Mocking
  • Moq
• Code coverage
  • coverlet.collector
  • ReportGenerator
• Utils
  • Bogus
  • Shouldly
  • FluentAssertions

PM> Install-Package Bogus -Version 32.0.2
PM> Install-Package coverlet.collector -Version 1.3.0
PM> Install-Package FluentAssertions -Version 5.10.3
PM> Install-Package Microsoft.NET.Test.Sdk -Version 16.8.3
PM> Install-Package Moq -Version 4.15.2
PM> Install-Package ReportGenerator -Version 4.8.1
PM> Install-Package Shouldly -Version 4.0.1

# NUnit
PM> Install-Package NUnit -Version 3.12.0
PM> Install-Package NUnit3TestAdapter -Version 3.17.0

# xUnit
PM> Install-Package xunit -Version 2.4.1
PM> Install-Package xunit.runner.visualstudio -Version 2.4.3

Syntax

Given-When-Then pattern

Martin Fowler's blog

Arrange-Act-Assert pattern

Docs.Microsoft

Moq setup and verify

// Setup async method when it returns data
mockService
    .Setup(_ => _.GetAsync(It.IsAny<int>()))
    .ReturnsAsync(It.IsAny<Data>())
    .Verifiable();

// Setup async method when it executes without a return type
mockService
    .Setup(_ => _.RunAsync())
    .ReturnsAsync(Task.CompletedTask)
    .Verifiable();

// Setup async method when it throws an exception
mockService
    .Setup(_ => _.RunAsync(It.IsAny<int>()))
    .Throws<Exception>()
    .Verifiable();

// Verify all service methods, marked as 'Verifiable'
mockService.VerifyAll();

// Verify individual service method
mockService.Verify(_ => _.GetAsync(It.IsAny<int>()), Times.Once);
mockService.Verify(_ => _.RunAsync(), Times.Exactly(2));
mockService.Verify(_ => _.RunAsync(It.IsAny<int>()), Times.Never);

Assertions

// NUnit
Assert.That(result, Is.InstanceOf<ObjectResult>());
var apiResponse = result as OkObjectResult;
Assert.That(apiResponse.StatusCode, Is.EqualTo((int)HttpStatusCode.OK));

// xUnit
var apiResponse = Assert.IsType<OkObjectResult>(result);
Assert.Equal((int)HttpStatusCode.OK, apiResponse.StatusCode);

// FluentAssertions
result
    .Should().BeOfType<OkObjectResult>("because we return content")
    .Which.StatusCode.Should().Be((int)HttpStatusCode.OK);
    
// Shouldly
result.ShouldSatisfyAllConditions(
    () => result.ShouldBeOfType<OkObjectResult>(),
    () => (result as OkObjectResult).StatusCode.ShouldBe((int)HttpStatusCode.OK));

Collect code coverage

Install coverlet.collector NuGet package

PM> Install-Package coverlet.collector -Version 1.3.0

TestProject.csproj configuration

<PackageReference Include="coverlet.collector" Version="1.3.0">
  <PrivateAssets>all</PrivateAssets>
  <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
</PackageReference>

Collector configuration. Add a file (e.g. runsettings) anywhere in the solution/project

<?xml version="1.0" encoding="utf-8" ?>
<RunSettings>
  <DataCollectionRunSettings>
    <DataCollectors>
      <DataCollector friendlyName="XPlat code coverage">
        <Configuration>
          <Format>json,cobertura</Format>
          <UseSourceLink>true</UseSourceLink>
          <IncludeTestAssembly>false</IncludeTestAssembly>
          <ExcludeByFile>**/**/Program.cs,**/**/Startup.cs,**/Dir/SubDir/*.cs</ExcludeByFile>
        </Configuration>
      </DataCollector>
    </DataCollectors>
  </DataCollectionRunSettings>
  <InProcDataCollectionRunSettings>
    <InProcDataCollectors>
      <InProcDataCollector
        assemblyQualifiedName="Coverlet.Collector.DataCollection.CoverletInProcDataCollector, coverlet.collector, Version=1.3.0.0, Culture=neutral, PublicKeyToken=null"
        friendlyName="XPlat Code Coverage"
        enabled="True"
        codebase="coverlet.collector.dll" />
    </InProcDataCollectors>
  </InProcDataCollectionRunSettings>
</RunSettings>

Run tests and collect data

PM> dotnet test --collect:"XPlat Code Coverage" --settings .\runsettings

PM> dotnet test .\Specific.Test.Project --collect:"XPlat Code Coverage" --settings .\Specific.Test.Project\runsettings

Generate Code Coverage Report

Install ReportGenerator NuGet package

PM> Install-Package ReportGenerator -Version 4.8.1

Generate reports

ReportGenerator usage page

PM> dotnet $(UserProfile)\.nuget\packages\reportgenerator\x.y.z\tools\netcoreapp3.0\ReportGenerator.dll "-reports:coverage.xml" "-targetdir:coveragereport" -reporttypes:Html
PM> dotnet $(UserProfile)\.nuget\packages\reportgenerator\x.y.z\tools\netcoreapp3.0\ReportGenerator.dll "-reports:coverage.xml" "-targetdir:coveragereport" -reporttypes:Badges

# CSharp.UnitTesting.Api NUnit
PM> dotnet $(UserProfile)\.nuget\packages\reportgenerator\4.8.1\tools\netcoreapp3.0\ReportGenerator.dll "-reports:CSharp.UnitTesting.Api.Nunit.Test\TestResults\*\coverage.cobertura.xml" "-targetdir:_CoverageReport\Api\NUnit" "-historydir:_CoverageReport\_History\Api\NUnit" -reporttypes:Html

# CSharp.UnitTesting.Api xUnit
PM> dotnet $(UserProfile)\.nuget\packages\reportgenerator\4.8.1\tools\netcoreapp3.0\ReportGenerator.dll "-reports:CSharp.UnitTesting.Api.Xunit.Test\TestResults\*\coverage.cobertura.xml" "-targetdir:_CoverageReport\Api\xUnit" "-historydir:_CoverageReport\_History\Api\xUnit" -reporttypes:Html