Code coverage extensions

This article lists and explains all Microsoft.Testing.Platform extensions related to the code coverage capability.

You can use the code coverage feature to determine what proportion of your project's code is being tested by coded tests such as unit tests. To effectively guard against bugs, your tests should exercise or cover a large proportion of your code.

Microsoft code coverage

Microsoft Code Coverage analysis is possible for both managed (CLR) and unmanaged (native) code. Both static and dynamic instrumentation are supported. This extension is shipped as part of Microsoft.Testing.Extensions.CodeCoverage NuGet package.

Note

Unmanaged (native) code coverage is disabled in the extension by default. Use flags EnableStaticNativeInstrumentation and EnableDynamicNativeInstrumentation to enable it if needed. For more information about unmanaged code coverage, see Static and dynamic native instrumentation.

Important

The package is shipped with Microsoft .NET library closed-source free to use licensing model.

For more information about Microsoft code coverage, see its GitHub page.

Microsoft Code Coverage provides the following options:

Option	Description
--coverage	Collect the code coverage using dotnet-coverage tool.
--coverage-output	The name or path of the produced coverage file. By default, the file is TestResults/<guid>.coverage.
--coverage-output-format	Output file format. Supported values are: coverage, xml, and cobertura. Default is coverage.
--coverage-settings	XML code coverage settings.

For more information about the available options, see settings and samples.

Note

The default value of IncludeTestAssembly in Microsoft.Testing.Extensions.CodeCoverage is false, while it used to be true in VSTest. This means that test projects are excluded by default. For more information, see Code Coverage configuration.

Version compatibility

The following table shows the compatibility between different versions of Microsoft.Testing.Extensions.CodeCoverage and Microsoft.Testing.Platform:

Microsoft.Testing.Extensions.CodeCoverage	Microsoft.Testing.Platform
18.1.x	2.0.x
18.0.x	1.8.x
17.14.x	1.6.2

Note

For the best compatibility and latest features, it's recommended to use the latest versions of both packages together.

Coverlet

The Coverlet Microsoft Testing Platform Integration (coverlet.MTP) is a native extension for Microsoft.Testing.Platform that implements coverlet.collector functionality.

Add the coverlet.MTP NuGet package to your test project:

dotnet add package coverlet.MTP

To collect code coverage, run your tests with the --coverlet flag:

dotnet test --coverlet

Or run your test executable with the --coverlet flag:

dotnet exec <test-assembly.dll> --coverlet

After the test run, a coverage.json file containing the results is generated in the current directory.

coverlet.MTP provides the following options:

Option	Description
--coverlet	Enable code coverage data collection.
--coverlet-output-format <format>	Output formats for the coverage report. Supported formats: json, lcov, opencover, cobertura, and teamcity. Specify multiple times to include more than one format.
--coverlet-include <filter>	Include assemblies that match filters, such as [Assembly]Type. Specify multiple times to add more filters.
--coverlet-include-directory <path>	Include extra directories for source files. Specify multiple times to add more directories.
--coverlet-exclude <filter>	Exclude assemblies that match filters, such as [Assembly]Type. Specify multiple times to add more filters.
--coverlet-exclude-by-file <pattern>	Exclude source files that match glob patterns. Specify multiple times to add more patterns.
--coverlet-exclude-by-attribute <attribute>	Exclude methods or classes decorated with specific attributes. Specify multiple times to add more attributes.
--coverlet-include-test-assembly	Include the test assembly in the coverage report.
--coverlet-single-hit	Limit the number of hits to one for each location in the code.
--coverlet-skip-auto-props	Skip auto-implemented properties in the coverage.
--coverlet-does-not-return-attribute <attribute>	Attributes that mark methods as not returning. Specify multiple times to add more attributes.
--coverlet-exclude-assemblies-without-sources <value>	Exclude assemblies without source code. Values: MissingAll, MissingAny, and None.

For more information, see the coverlet.MTP documentation.