Index was out of range. VSTS

The VSTS agent is running in docker, image: microsoft/vsts-agent:ubuntu-16.04-standard. The same test command works locally. I found #135 but I’m not using multiple output formats.

2018-08-22T07:24:52.2980413Z 09:19:02.029   1:7>Target "GenerateCoverageResult: (TargetId:266)" in file "/root/.nuget/packages/coverlet.msbuild/2.2.1/build/netstandard2.0/coverlet.msbuild.targets" from project "/vsts/agent/_work/1/s/eMeM.Tests/eMeM.Tests.csproj" (entry point):
2018-08-22T07:24:52.2998339Z                    Using "Coverlet.MSbuild.Tasks.CoverageResultTask" task from assembly "/root/.nuget/packages/coverlet.msbuild/2.2.1/build/netstandard2.0/coverlet.msbuild.tasks.dll".
2018-08-22T07:24:52.3015351Z                    Task "Coverlet.MSbuild.Tasks.CoverageResultTask" (TaskId:172)
2018-08-22T07:24:52.3032017Z                      Task Parameter:Output=/vsts/agent/_work/1/s/eMeM.Tests/ (TaskId:172)
2018-08-22T07:24:52.3048643Z                      Task Parameter:OutputFormat=cobertura (TaskId:172)
2018-08-22T07:24:52.3065096Z                      Task Parameter:Threshold=0 (TaskId:172)
2018-08-22T07:24:52.3081839Z                      Task Parameter:ThresholdType=line,branch,method (TaskId:172)
2018-08-22T07:24:52.3090313Z 
2018-08-22T07:24:52.3107632Z Calculating coverage result...
2018-08-22T07:24:52.3124707Z   Generating report '/vsts/agent/_work/1/s/eMeM.Tests/coverage.cobertura.xml'
2018-08-22T07:24:52.3143040Z 09:19:02.069   1:7>/root/.nuget/packages/coverlet.msbuild/2.2.1/build/netstandard2.0/coverlet.msbuild.targets(23,5): error : Index was out of range. Must be non-negative and less than the size of the collection. [/vsts/agent/_work/1/s/eMeM.Tests/eMeM.Tests.csproj]
2018-08-22T07:24:52.3161444Z /root/.nuget/packages/coverlet.msbuild/2.2.1/build/netstandard2.0/coverlet.msbuild.targets(23,5): error : Parameter name: index [/vsts/agent/_work/1/s/eMeM.Tests/eMeM.Tests.csproj]
2018-08-22T07:24:52.3178877Z                    Done executing task "Coverlet.MSbuild.Tasks.CoverageResultTask" -- FAILED. (TaskId:172)

I tracked it up to here https://www.fuget.org/packages/coverlet.msbuild/2.2.1/build/netstandard2.0/coverlet.msbuild.tasks.dll/Coverlet.MSbuild.Tasks/CoverageResultTask?code=true#M:Coverlet.MSbuild.Tasks.CoverageResultTask.Execute but I’m not sure where to find the relevant piece of code.

[csharpsi]

I know this is closed, but for what it’s worth, I was hitting this problem when setting up a new project build pipeline using an app that didn’t yet have any implementation. I wanted to get the build pipeline including tests and coverage set up prior to starting work. Anyway, the reason I was getting this error was I hadn’t yet referenced the app project from the test project. Adding the following to my test project csproj solved the problem.

<ItemGroup>
    <ProjectReference Include="..\..\App.csproj" />
</ItemGroup>

It’s looking for assemblies with which to measure coverage against and not finding any (obvious now I think about it!). The error message could possibly be a bit clearer?

[MortenChristiansen]

I get the same error, but only after upgrading to version 2.3.1 of the coverlet.msbuild package. If I revert to 2.3.0, it works again. It appears to be related to the fact that 2 of my 3 test projects only have a single placeholder test. I do reference the projects under test, including a class from the projects, so the fix mentioned by @csharpsi does not work.