Coverlet vs Microsoft Code Coverage

Coverlet is a free, MIT-licensed code coverage framework for modern .NET SDK-style projects. It measures line, branch, and method coverage across Linux, macOS, and Windows. Before tests execute, Coverlet instruments assemblies, records sequence-point hits, restores the original assemblies, and writes coverage results. Drivers are available for Microsoft Testing Platform, the .NET global tool, VSTest, and MSBuild. The Microsoft Testing Platform driver can emit JSON, LCOV, OpenCover, and Cobertura reports. Depending on the driver, teams can merge reports, validate coverage thresholds, and support deterministic builds. Collector and MSBuild packages use VSTest; Microsoft Testing Platform projects instead use coverlet.MTP, which requires the .NET 8.0 SDK or newer. Cake.Coverlet and Visual Studio viewing extensions are also listed. Coverage gates are supported, and bugs or feature requests go through the repository issues section.

Microsoft Code Coverage measures how much of a project’s code is exercised by coded tests, such as unit tests. Its documented workflows cover.NET test projects with `dotnet test` and other.NET applications with the `dotnet-coverage` tool. It analyzes managed CLR and unmanaged native code using static or dynamic instrumentation; native coverage is disabled by default in the MTP extension. With Microsoft.Testing.Platform.MSBuild, extensions are auto-registered with MSTest, NUnit, and xUnit runners. The MTP extension can produce coverage, XML, and Cobertura reports, with settings for output, inclusion and exclusion rules, and instrumentation. It runs on Windows, macOS, and multiple Linux distributions, though instrumentation support varies by OS, version, and architecture. Other operating systems are supported on a best-effort basis, and some combinations allow static instrumentation only. Dynamic instrumentation on macOS and Linux requires libxml2, and missing dependencies may leave a report empty. MTP also excludes test assemblies by default unless configured otherwise. The plan is free.