Coverlet Coverage does not match coverage reported from Report Generator reports

[joshclark]

When coverlet runs on my project it reports 72.7%. When I take the output (I used the opencover reporter) and run that through ReportGenerator, it shows the coverage as 66.7%. If I change the output to Cobertura I get 62.2%

Opening the coverage.xml file I see this summary:

  <Summary numSequencePoints="2015" 
           visitedSequencePoints="1254" 
           numBranchPoints="142" 
           visitedBranchPoints="142" 
           sequenceCoverage="0.727" 
           branchCoverage="0.727" 
           maxCyclomaticComplexity="0" 
           minCyclomaticComplexity="0" 
           visitedClasses="120" 
           numClasses="203" 
           visitedMethods="310" 
           numMethods="447" />

It looks like the sequenceCoverage attribute matches what coverlet reports. It looks like visitedSequencePoints / numSequencePoints matches what ReportGenerator is reporting for Cobertura.

I would expect the two tools to report the same value. I have not yet researched where those numbers are coming from.

Update:
It looks like the problem might be here (https://github.com/tonerdo/coverlet/blob/master/src/coverlet.core/CoverageSummary.cs) where the code takes the average of averages rather than calculating the actual average from the raw data.

[hunterjm]

See #73

[tonerdo]

Will have a release with this fix by Monday

[tonerdo]

New version released https://www.nuget.org/packages/coverlet.msbuild/2.0.0