altcover 8.6.14

There is a newer version of this package available.
See the version list below for details.
dotnet add package altcover --version 8.6.14                
NuGet\Install-Package altcover -Version 8.6.14                
This command is intended to be used within the Package Manager Console in Visual Studio, as it uses the NuGet module's version of Install-Package.
<PackageReference Include="altcover" Version="8.6.14" />                
For projects that support PackageReference, copy this XML node into the project file to reference the package.
paket add altcover --version 8.6.14                
#r "nuget: altcover, 8.6.14"                
#r directive can be used in F# Interactive and Polyglot Notebooks. Copy this into the interactive tool or source code of the script to reference the package.
// Install altcover as a Cake Addin
#addin nuget:?package=altcover&version=8.6.14

// Install altcover as a Cake Tool
#tool nuget:?package=altcover&version=8.6.14                


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.


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 Visualizer screenshot

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 Build statusBuild history
Test coverage Coveralls Coverage Status

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

Product Compatible and additional computed target framework versions.
.NET net5.0 was computed.  net5.0-windows was computed.  net6.0 was computed.  net6.0-android was computed.  net6.0-ios was computed.  net6.0-maccatalyst was computed.  net6.0-macos was computed.  net6.0-tvos was computed.  net6.0-windows was computed.  net7.0 was computed.  net7.0-android was computed.  net7.0-ios was computed.  net7.0-maccatalyst was computed.  net7.0-macos was computed.  net7.0-tvos was computed.  net7.0-windows was computed.  net8.0 was computed.  net8.0-android was computed.  net8.0-browser was computed.  net8.0-ios was computed.  net8.0-maccatalyst was computed.  net8.0-macos was computed.  net8.0-tvos was computed.  net8.0-windows was computed. 
.NET Core netcoreapp2.0 was computed.  netcoreapp2.1 was computed.  netcoreapp2.2 was computed.  netcoreapp3.0 was computed.  netcoreapp3.1 was computed. 
.NET Standard netstandard2.0 is compatible.  netstandard2.1 was computed. 
.NET Framework net20 is compatible.  net35 was computed.  net40 was computed.  net403 was computed.  net45 was computed.  net451 was computed.  net452 was computed.  net46 was computed.  net461 was computed.  net462 was computed.  net463 was computed.  net47 was computed.  net471 was computed.  net472 was computed.  net48 was computed.  net481 was computed. 
MonoAndroid monoandroid was computed. 
MonoMac monomac was computed. 
MonoTouch monotouch was computed. 
Tizen tizen40 was computed.  tizen60 was computed. 
Xamarin.iOS xamarinios was computed. 
Xamarin.Mac xamarinmac was computed. 
Xamarin.TVOS xamarintvos was computed. 
Xamarin.WatchOS xamarinwatchos was computed. 
Compatible target framework(s)
Included target framework(s) (in package)
Learn more about Target Frameworks and .NET Standard.

This package has no dependencies.

NuGet packages

This package is not used by any NuGet packages.

GitHub repositories (20)

Showing the top 5 popular GitHub repositories that depend on altcover:

Repository Stars
A cross-platform .NET library for IMAP, POP3, and SMTP.
Simple, powerful, cross-platform SQLite client and ORM for .NET
A simple package with guard clause extensions.
ReportGenerator converts coverage reports generated by coverlet, OpenCover, dotCover, Visual Studio, NCover, Cobertura, JaCoCo, Clover, gcov or lcov into human readable reports in various formats.
A .NET MIME creation and parser library with support for S/MIME, PGP, DKIM, TNEF and Unix mbox spools.
Version Downloads Last updated
8.8.74 20,802 5/31/2024
8.8.53 8,696 5/16/2024
8.8.21 24,797 4/15/2024
8.8.10 7,878 4/6/2024
8.7.3 22,396 3/14/2024
8.6.125 62,234 1/4/2024
8.6.95 24,371 11/14/2023
8.6.68 122,838 7/10/2023
8.6.61 25,496 6/6/2023
8.6.45 79,327 3/21/2023
8.6.40 12,697 3/16/2023
8.6.14 112,549 1/1/2023
8.5.842 12,040 12/25/2022
8.5.841 30,511 11/19/2022
8.4.840 50,869 10/17/2022
8.3.839 24,617 9/13/2022

This build from

Q. Never mind the fluff -- how do I get started?
A. Start with the Quick Start guide : and
read the FAQ :

8.6.14 (Habu series release 19)
• [GTKVisualizer] Fix an off-by-one crash for coverlet generated files
• [AvaloniaVisualizer] Fix possible crash launching the About dialog
• [Visualizer] Display coverage percentages against nodes of the tree (known issue that the synthetic F# module nodes are not thus decorated)
• [Visualizer] Improve handling of larger coverage files by deferring more processing until the tree model is actually expanded.
• [API] Types Options.CLI, Options.Logging, Options.Prepare and Options.Collect in namespace AltCover; concrete implementations of the ICLIOptions, ILoggingOptions and IPrepareOptions and ICollectOptions respectively, with getter and setter for each property.  Default values for the latter two are as per the corresponding Primitive record types.
• [API] Also on the AltCover.Fake package in the AltCoverFake.DotNet.Testing namespace (except Options.Logging which is not useful in that context)

8.5.842 (Habu series release 18)
• [VISUALIZER] As the relevant Avalonia issue is long resolved, move to having separate dialog boxes for the Avalonia Visualizer's "About" and message box, as in the GTK# version.
• ref struct types have an autogenerated [Obsolete] attribute with a standard comment - detect and ignore such attributes.  See for details.

8.5.841 (Habu series release 17)
• To support Cake 3.0, move the Cake API assembly from AltCover.Api to a new package AltCover.Cake; this contains libraries built against Cake 2.0.0 at netcoreapp3.1 as well as the old ones built against Cake 1.0.0 at netstandard2.0 (present but in practice obsolete).
• Following's policy of deprecating releases older then 6 month, drop support for versions before 5.23
• [BREAKING] Rename AltCover.Cake.DotNet.DotNetCoreTest to AltCover.Cake.DotNet.DotNetTest (even in the obsolete 1.0.0 build) to match the changes in the Cake APIs (and consequent chage to the test setting type in the argument list).  Similarly, in the version >= 2.0.0 build, the type AltCover.Cake.DotNet is now a [CakeAliasCategory("DotNet")] rather than [CakeAliasCategory("DotNetCore")]
• [API] New DotNet APIs for Fake support - ToTestPropertiesList method to emit a list of (name,value) pairs to allow customised property passing to dotnet test in the wake of the v7.0.100 regression.
• [API] Additionally ImportModuleProperties and GetVersionProperties values that are additonal lists of (name,value) pairs to append as needed.

8.4.840 (Habu series release 16)
• New option --trivia to omit coverage of sequence points containing no logic (no-op, return or unconditional branches only)
• Added context for exceptions thrown during instrumentation.  This is aimed at tracing what was being inspected when exceptions arise from Mono.Cecil being presented with a new corner case.

8.3.839 (Habu series release 15)
• [BUGFIX] -- Issue #161: Add retry logic to ContingentCopy task
• [BUGFIX] -- Issue #165: Work around Cecil issue #873 by omitting debug information for constants that cause that issue. N.B. will not catch cases in methods that are not instrumented.

8.3.838 (Habu series release 14)
• [GTK-VISUALIZER] Fix off-by-one error in markup for the very last line of the file
• [BUGFIX] -- Out-of-process APIs generating dotnet test: fix to allow activating ZipFile, MethodPoint, SingleVisit and SourceLink
• [BUGFIX] -- Issue #156: Out-of-process APIs generating dotnet test: fix /p:AltCoverDependencyList to work around the behaviour of dotnet test with an argument ending .dll or .exe.  Users rolling their own command lines, note that the assembly list is separated and terminated with '|' characters.  The --dependency command line argument for the tool is not affected.
• [BUGFIX] -- Issue #156: Make explicit dependencies through --dependency have priority over other assembly resolution lookup.  This works around a Mono.Cecil misfeature (Mono.Cecil issue #863) where the netstandard2.0 Cecil binaries do not consider the GAC for Framework system assemblies, but instead will find stubs in dotnet/shared/Microsoft.NETCore.App for e.g. .net Framework WPF related assemblies
• [BUGFIX] -- Improve selection of non-embedded symbol files (between location in assembly debug header, the same directory as the assembly and any --symbolDirectory values) to avoid symbol mismatch when there are multiple possible files on offer
• Add a --verbose option for AltCover, the converse of -q.  Away from the command line, adds meaning to the Verbosity option value System.Diagnostics.TraceLevel.Verbose.  Currently Verbose output shows more of the selection of files for instrumentation, noting when files are excluded from the process, symbol file selection etc.
• Add a matching field, ILoggingOptions.Verbose, to the API as a sink to capture verbose output.
• Other minor build process adjustments for SDK 6.0.300/F# 6.0.4, 6.0.5

8.2.837 (Habu series release 13)
• [VISUALIZER] Critical bug fixes for GTK and Avalonia : mismatched new icon names causing crashes
• [VISUALIZER] Use new coverage data icon for the coverage report file, not a generic report icon

8.2.836 (Habu series release 12)
• [BUGFIX] Fix project file path handling in Cake support
• [BUGFIX] Improve heuristic to recognise (and ignore)  state-machine injected branches in async methods; this may cause subtle changes, up or down, in branch detection for other generated code ("hidden" sequence points) contexts with branches
• Use VS2022 icons in the Visualizer

8.2.835 (Habu series release 11)
• [BUGFIX] Fix tracked methods in the Merge-OpenCover cmdlet
• [BUGFIX] Fix blocking issue in Cake support; and add operational test
• Move Fake.Build support to 5.21 as minimum; updating other supporting libraries

8.2.833 (Habu series release 10)
• [BUGFIX] Work-round more (problems with ill-formed debug data)[] (issue #135)
• [BUGFIX] An infinite loop while instrumenting when faced with an inner function that is also a closure (also issue #135)
• [BUGFIX] Address issue #71 by pre-allocating storage for each instrumented assembly; rather than allocating on demand, with any timing related issues not adequately dealt with subject to catch-and-ignore
• For instrumented assemblies, write embedded debug symbols, independent of the input choice.
• Improved release note formatting
• Some overhaul and updating of neglected parts of the build and test script
• Reduce to a minimum the differences in the source between the net20 and net46-for-async versions of the recorder; then just rewrite the net20 version with the delta on demand.
• Some minor improvements to the data collector for dotnet test use, with example of how to employ explicitly in AltCover "classic" mode in the "UnitTestWithAltCoverCore" fake build target

8.2.831 (Habu series release 9)
• [BUGFIX] Make the static-linked parts of the recorder assembly internal, so only the AltCover instrumentation API is exposed -- removes type duplications from the environment that may confuse run-time assembly creation e.g. by Marten (issue #133)
• For CallContext, add async-aware tracking for all methods returning Task or Task<T> not just ones with the C# async shape.  This includes functions returning the new F#6 task{} computation expression.
◦ Note there is a support gap : running this under .net Framework less than v4.6 (i.e. a test machine with a pre-2015-JUL-20 environment) will not work, even though Task is a .net 4.0 feature, as the tracking support relies on .net 4.6 async features.
• Emit (a warning)[] if any of the files input to the instrumentations have previously been instrumented, leaving those files untouched (apart from any Recorder assembly, which will still be overwritten).  For dotnet test this is an MSBuild warning, for powershell, it is delivered via Cmdlet.WriteWarning.
◦ This behaviour is subject to change in future releases
• Rework of the build process to keep artifacts out of the tracked directories

8.2.828 (Habu series release 8)
• Absorb .net 6 release into build tooling (awaiting a non-preview updated release of ([] to be able to upgrade to FSharp.Core 6.x -- still have to target the v5.x library even if the build uses the F#6 compiler)
• Where the debug symbols used in the instrumentation contain embedded source (e.g. from source generators), represent that within the generated report --
◦ for OpenCover format, as an altcover.embed attribute added to the File element
◦ for NCover classic, altcover.file elements are added after the method records in a module, with attributes document and embed
◦ and for the extended coverlet JSON format, as a type «AltCover.embed» with an empty method with name being the embedded text.
• [VISUALIZER] Support the extended formats for display, using the embedded source in preference to the file system whenever present
• Support these extensions in conversions between formats -- conversion to Lcov and Cobertura currently lose this information
• Other fixes/enhancements to these conversions, esp. in the cases of partial classes and inlined code
• Compute summary data correctly in the output from Json to OpenCover
• Carry both recorder versions (net20 and net46) as resources to simplify self-test behaviour
• Move baseline Cake support to v1.1.0 and Fake to v5.20.4

8.2.825 (Habu series release 7)
• Next release will be post .net 6 release to accomodate its impact, barring show-stoppers
• [BUGFIX] As noted in Q&A discussion (#107), satellite assemblies, and in issue #47  platform specific library subfolders, were not being copied appropriately relative to the instrumented location; this is now resolved.
• [BUGFIX] Prevent --localSource possibly excluding locally built assemblies using source generators.
• [VISUALIZER] Fixes and updates
◦ On the global tool, don't put expander icons (˃) on leaf nodes, i.e. most methods, all source -- such icons are an automatic feature in GTK, but are manual in Avalonia.
◦ Don't throw while trying to determine if a file that doesn't exist is outdated

8.2.824 (Habu series release 6c)
• [VISUALIZER] Fixes and updates
◦ [REGRESSION] Fix where multiple source file support broke JSON coverage support
◦ Not all coverage reports are XML -- fix root node icon
◦ Add more icons indicating non-default states (files missing, changed, via sourcelink &c)
◦ Replace most of the annoying pop-ups with tool-tips

8.2.823 (Habu series release 6b)
• [VISUALIZER] Fixes and updates
◦ [REGRESSION] Fix where multiple source file support broke methods with no source file
◦ [BUGFIX] Fix where some types were erroneously shown as functions (ƒₓ)
◦ Allow for TAB characters (which occupy 1 column only in the .PDB), and display → rather than ◻ in the global tool (TAB expands to 8 spaces in the GTK# build)
◦ Update icons to VS2019 from VS2017 (except where taken from GTK in the GTK# build), which means slightly more colours in the tree view, and a small change to the branch indicator.

8.2.822 (Habu series release 6a)
• [VISUALIZER] Support OpenCover's output from C++/CLI assemblies compiled /Zi (line information only, zero column values)
◦ account for (& simplify) the C++/CLI attribute decorations in method names
◦ allow for (& simplify) gcroot<type::with::Cpp::namespacing ^> types in method names
◦ allow source file selection for methods with code inlined from multiple source files

8.2.821 (Habu series release 6)
• Support deterministic builds /p:ContinuousIntegrationBuild=true, with or without --sourcelink//p:AltCoverSourceLink=true.  Note that assemblies created by deterministic builds will be excluded by -l//p:AltCoverLocalSource=true.
• Experiment with the ReadMe feature recently added to NuGet
• Internal refactoring of the JSON processing following the replacement of System.Text.Encodings.Web in the previous release.

8.2.820 (Habu series release 5)
• Replace System.Text.Encodings.Web for JSON-escaping module, class and method names
• [BUGFIX] issue #125 -- prevent an NullReferenceException in some cases of computing cyclomatic complexity (a failure to exactly copy the algorithm from Mono.Gendarme)
• [ENHANCEMENT; API] issue #126 -- further generalise the relative-directory support for CopyAlways/CopyIfNewer from v7.4; extends the ContingentCopy MSBuild task

For previous releases (8.1.x and earlier) go here --