altcover

Instrumenting coverage tool for .net (framework 2.0+ and core) and Mono assemblies, reimplemented and extended almost beyond recognition from dot-net-coverage, plus a set of related utilities for processing the results from this and from other programs producing similar output formats.

Usage

See the Wiki page for full details

I really want coverage for my .net core unit test project right now

Install into your test project

dotnet add package AltCover

and run

dotnet test /p:AltCover=true

The OpenCover format output will be in file coverage.xml in the project directory

What's in the box?

For Mono, .net framework and .net core, except as noted

• AltCover, a command-line tool for recording code coverage (net472 and .netcoreapp2.0)
• MSBuild tasks to drive the tool, including dotnet test integration
• A PowerShell module for Windows PowerShell 5.1 and PowerShell Core 6+ containing a cmdlet that drives the tool, and other cmdlets for manipulating coverage reports
• A coverage visualizer tool (net472) -- for .net framework, needs GTK# v2.12.xx installed separately

Why altcover?

As the name suggests, it's an alternative coverage approach. Rather than working by hooking the .net profiling API at run-time, it works by weaving the same sort of extra IL into the assemblies of interest ahead of execution. This means that it should work pretty much everywhere, whatever your platform, so long as the executing process has write access to the results file. You can even mix-and-match between platforms used to instrument and those under test.

In particular, while instrumenting .net core assemblies "just works" with this approach, it also supports Mono, as long as suitable .mdb (or .pdb, in recent versions) symbols are available. One major limitation here is that the .mdb format only stores the start location in the source of any code sequence point, and not the end; consequently any nicely coloured reports that take that information into account may show a bit strangely.

Why altcover? -- the back-story of why it was ever a thing

Back in 2010, the new .net version finally removed the deprecated profiling APIs that the free NCover 1.5.x series relied upon. The first version of AltCover was written to both fill a gap in functionality, and to give me an excuse for a ground-up F# project to work on. As such, it saw real production use for about a year and a half, until OpenCover reached a point where it could be used for .net4/x64 work (and I could find time to adapt everything downstream that consumed NCover format input).

Fast forwards to autumn 2017, and I get the chance to dust the project off, with the intention of saying that it worked on Mono, too -- and realise that it's déja vu all over again, because .net core didn't yet have profiler based coverage tools either, and the same approach would work there as well.

Continuous Integration

Build	GitHub
Test coverage	Coveralls

Possible retirement/obsolescence of support

tl;dr -- legacy framework/Mono support is not going away any time soon.

As net472 can consume netstandard2.0 libraries (everything but the recorder), and .net core 2+ can consume net20 libraries (the recorder), legacy framework/Mono support continues until such a time as it is no longer possible to retain those API levels.

Other NuGet Packages in this suite

• API install -- excludes the visualizer in all forms
• dotnet global tool install -- excludes the visualizer in all forms
• Visualizer dotnet global tool -- just the .net core/Avalonia Visualizer as a global tool
• FAKE build task utilities -- just AltCover related helper types for FAKE scripts (v5.23.0 or later), only in this package
• Cake build task utilities -- just AltCover related helper types for Cake scripts (v2.0.0 or later), only in this package