.NET Test Coverage

SonarCloud supports the reporting of test coverage information as part of the analysis of your .NET project.

However, SonarCloud does not produce the coverage report itself. Instead, you must set up a third-party tool to produce the report as part of your build process. You then need to configure your analysis to tell the SonarScanner where the report is located so that it can pick it up and send it to SonarCloud, where it will be displayed on your project dashboard along with the other analysis metrics.

SonarCloud supports the following .NET test coverage tools:

  • Visual Studio Code Coverage
  • dotnet-coverage Code Coverage
  • dotCover
  • OpenCover
  • Coverlet

Follow the tutorial

When you import your .NET project into SonarCloud, you will be guided through the setup process by an in-product tutorial. Once you have completed the tutorial, you should have a working analysis setup. The next step is to adjust that setup to enable coverage reporting.

Adding coverage to your build process

The .NET scanner comes in four variants depending on which version of .NET and which CI you are using (.NET Framework, .NET Core, .NET tool and SonarScanner for Azure DevOps). The setup is slightly different for each variant (see the SonarScanner for .NET and SonarScanner for Azure DevOps sections for details), but the essential steps are the same.

The analysis is always split into two parts in your build process; the begin step and the end step. In between, you perform the actual build and your tests. To enable coverage reporting, you need to make the following changes:

  • In the scanner begin step, add the appropriate parameter to specify the location of the coverage report file that will be produced.
  • Just after the build step but before the scanner end step, ensure that your test step produces the coverage report file.

Examples using the .NET tool scanner variant

The SonarScanner for .NET comes in four major variants: .NET Framework 4.6, .NET Core, .NET tool, and Azure Pipelines extension.

Visual Studio Code Coverage

We only recommend the use of this tool when the build agent has Visual Studio Enterprise installed or when you are using an Azure DevOps Windows image for your build. In these cases, the .NET Framework 4.6 scanner will automatically find the coverage output generated by the --collect "Code Coverage" parameter without the need for an explicit report path setting. It will also automatically convert the generated report to XML. No further configuration is required. Here is an example:

SonarScanner.MSBuild.exe begin /k:"<sonar-project-key>" /d:sonar.login="<sonar-token>" 
dotnet build --no-incremental
dotnet test --collect "Code Coverage"
SonarScanner.MSBuild.exe end /d:sonar.login="<sonar-token>"

dotnet-coverage

This is a modern alternative to the Visual Studio Code Coverage provided by Microsoft (see above) that outputs results in the same format, is cross-platform and not dependent on having Visual Studio installed. It requires .NET Core 3.1 or later.

To use dotnet-coverage, you must install it as a global dotnet tool:

dotnet tool install --global dotnet-coverage

Using this tool, your build script would look like something like this:

dotnet sonarscanner begin /k:"<sonar-project-key>"
    /d:sonar.login="<sonar-token>"
    /d:sonar.cs.vscoveragexml.reportsPaths=coverage.xml
dotnet build --no-incremental
dotnet-coverage collect 'dotnet test' -f xml  -o 'coverage.xml'
dotnet sonarscanner end /d:sonar.login="<sonar-token>"

Note that we specify the path to the reports using sonar.cs.vscoveragexml.reportsPaths because this tool’s output format is the same as the Visual Studio Code Coverage tool. We use the -f xml parameter to specify that the output format is in XML.

dotCover

To use dotCover you must install it as a global dotnet tool:

dotnet tool install --global JetBrains.dotCover.GlobalTool

Using this tool, your build script would look like something like this:

dotnet sonarscanner begin /k:"<sonar-project-key>"
    /d:sonar.login="<sonar-token>"
    /d:sonar.cs.dotcover.reportsPaths=dotCover.Output.html
dotnet build –no-incremental
dotnet dotcover test --dcReportType=HTML
dotnet sonarscanner end /d:sonar.login="<sonar-token>"

Note that we specify the path to the reports using sonar.cs.dotcover.reportsPaths because we are using dotCover.

OpenCover

To use OpenCover you must download it from here and unzip it in an appropriate directory, for example: C:\tools\opencover

Using this tool, your build script would look like something like this:

dotnet sonarscanner begin /k:"<sonar-project-key>"
    /d:sonar.login="<sonar-token>"
    /d:sonar.cs.opencover.reportsPaths=coverage.xml
dotnet build --no-incremental
& C:\tools\opencover\OpenCover.Console.exe -target:"dotnet.exe" 
    -targetargs:"test --no-build"
    -returntargetcode
    -output:coverage.xml
    -register:user
dotnet sonarscanner end /d:sonar.login="<sonar-token>"

Note that we specify the path to the reports using sonar.cs.opencover.reportsPaths because we are using OpenCover.

Coverlet

To use Coverlet, you must install it as a global dotnet tool:

dotnet tool install --global coverlet.console

You also have to install the coverlet collector NuGet package on your test project.

Using this tool, your build script would look like something like this:

dotnet sonarscanner begin /k:"<sonar-project-key>"
    /d:sonar.login="<sonar-token>"
    /d:sonar.cs.opencover.reportsPaths=coverage.xml
dotnet build --no-incremental
coverlet .\CovExample.Tests\bin\Debug\net6.0\CovExample.Tests.dll
    --target "dotnet" 
    --targetargs "test --no-build"
    -f=opencover 
    -o="coverage.xml"
dotnet sonarscanner end /d:sonar.login="<sonar-token>"

Note that we specify the path to the reports in sonar.cs.opencover.reportsPaths because Coverlet produces output in the same format as OpenCover.

.NET Framework and .NET Core scanners

In most of the examples above, we use the .NET tool scanner variant. If you use the .NET Framework or .NET Core scanner, the commands will be a bit different but the pattern will be the same. See SonarScanner for .NET for details.

SonarScanner for Azure DevOps

Using the SonarScanner for Azure DevOps and Visual Studio Code Coverage with a C# project,  your azure-pipelines.yml would look something like the example below.

Note that with the SonarScanner for Azure DevOps extension, the scanner begin step is handled by the SonarCloudPrepare task and the scanner end step is handled by the SonarCloudAnalyze task.

Also note that because our build is running on Windows (we specify vmImage: windows-latest), we do not need to explicitly specify the path to the coverage report (there is no sonar.cs.vscoveragexml.reportsPaths=coverage.xml) nor do you need to run codecoverage.exe to convert the report to XML.

azure-pipelines.yml

trigger:
- master

variables:
- name: system.debug
  value: true 

pool:
  vmImage: windows-latest

steps:
- task: DotNetCoreCLI@2
  inputs:
    command: 'restore'
    projects: 'my-project.sln'
    feedsToUse: 'select'

- task: SonarCloudPrepare@1
  inputs:
    SonarCloud: 'SonarCloud'
    organization: 'my-organization'
    scannerMode: 'MSBuild'
    projectKey: 'my-project-key'
    projectName: 'my-project'

- task: DotNetCoreCLI@2
  inputs:
    command: 'build'
    projects: 'my-project.sln'

- task: DotNetCoreCLI@2
  inputs:
    command: 'test'
    projects: 'tests/**/*.csproj'
    arguments: '--collect "Code Coverage"'

- task: SonarCloudAnalyze@1

VB.NET

The examples above are all for C# projects. For VB.NET projects the setup is identical except that you would use these parameters:

  • sonar.vbnet.vscoveragexml.reportsPaths for Visual Studio Code Coverage
  • sonar.vbnet.dotcover.reportsPaths for dotCover
  • sonar.vbnet.opencover.reportsPaths for OpenCover or Coverlet

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