Windows build produces much higher coverage results than macOS.

[parekhkb]

I am running dotnet test on multiple test projects and attempting to merge the output.

dotnet test "/Users/parekhkb/UnitTests/ProjectA.Test/Xxx.ProjectA.Test.csproj" --configuration Debug --no-build --no-restore /property:CollectCoverage=true /property:CoverletOutput=/Users/parekhkb/out/CodeCoverageResult/CoverageReport /property:CoverletOutputFormat=\"json,opencover\" /property:Exclude=\"[Xxx*.Test*],[Xxx.Data.Database.*],[Xxx.*Data*.Migrations.*]\" 

dotnet test "/Users/parekhkb/UnitTests/ProjectB.Test/Xxx.ProjectB.Test.csproj" --configuration Debug --no-build --no-restore /property:CollectCoverage=true /property:CoverletOutput=/Users/parekhkb/out/CodeCoverageResult/CoverageReport /property:CoverletOutputFormat=\"json,opencover\" /property:Exclude=\"[Xxx*.Test*],[Xxx.Data.Database.*],[Xxx.*Data*.Migrations.*]\" 
/property:MergeWith=/Users/parekhkb/out/CodeCoverageResult/CoverageReport.json

On macOS I get a result of 22.4% line coverage. But the same run on windows produces 72.5% line coverage.

UPDATE:
When I run the same set of runs without the MergeWith, I get drastically lower coverage results, which gives me new information. My final test run in the list is our Integration test suite. In that suite we setup our async worker background process, we then make web requests against a TestServer (in-process) and verify data directly in the DB. This is where a bulk of our test coverage comes from.

On windows, instrumentation of these the web server and the background worker seems to work fine, although they produce slightly less coverage than DotCover or OpenCover. But on macOS these tests result in 0% coverage.

[MarcoRossignoli]

But on macOS these tests result in 0% coverage.

Could be a dup of #110 can you try with collectors?

[MarcoRossignoli]

Close for stale, feel free to re-open if needed.