Coverage is overwritten if the project has multiple target frameworks

[SteveGilham]

If a system under test has multiple target frameworks, then

dotnet test /p:CollectCoverage=true

runs multiple coverage runs, overwriting the coverage output each time.

This is the equivalent of AltCover issue #31.

[tonerdo]

Thanks for reporting this. Will check it out

[joymon]

+1
Same issue here. Due to overwriting its difficult. Work around seems having one project / target framework. But it beat the purpose of multi targeting.

[jherby2k]

Workaround is just to run dotnet test with -f <framework>, grab the coverage.xml, then run it again with -f <other_framework>

[viceice]

Our workaround is to use merging and two output formats:

/p:CollectCoverage=true /p:CoverletOutput=./TestResults/ /p:CoverletOutputFormat=\"json,cobertura\" /p:MergeWith=./TestResults/coverage.json

[clairernovotny]

I would suggest that the tfm be added to the output file name in this scenario, yielding multiple output files. ReportGenerator or something else can merge them then.

[clairernovotny]

Here's another workaround --

In my Directory.Build.targets file, I have this:

  <PropertyGroup>
    <IsTestProject>$(MSBuildProjectName.Contains('Test'))</IsTestProject>
  </PropertyGroup>

  <PropertyGroup Condition="'$(IsTestProject)' == 'true'">
    <UseSourceLink>true</UseSourceLink>
    <CoverletOutputFormat>cobertura</CoverletOutputFormat>
    <Exclude>[xunit.*]*</Exclude>
    <CoverletOutput>$(MSBuildThisFileDirectory)coverlet/$(AssemblyName)/$(TargetFramework)/</CoverletOutput>
  </PropertyGroup>

It then creates a subdirectory for each assembly and target framework, enabling me to run dotnet test with a wildcard.