Inconsistent coverage results using dotCover console runner with .NET Core unit tests or vstest.console.exe.

Affected versions: 2018.1.1 - 2019.2.2

Symptoms

The coverage results are always 0% or change from run to run (even if there were no changes in the analyzed assemblies).

Possible cause

1. dotCover 2019.2: When covering "dotnet test" on a solution level, dotCover analyzes only the first .csproj with unit tests (other projects are not analyzed).
2. dotCover 2019.1 and earlier: When covering "dotnet test", "dotnet vstest" or vstest.console.exe (version 2017 and later), dotCover might get 0% coverage because the process with tests is killed by test platform before dotCover has a chance to save a snapshot.

Workaround (only for dotCover 2019.1 and earlier)

dotCover console runner:

• You have a Windows machine with installed dotCover 2018.1.1 or later.
• You have a .NET Core unit test project or use vstest.console.exe to run tests.
• You want to perform coverage analysis of unit tests via the command line.

To perform coverage analysis:

1. Create (or modify an existing) a .runsettings file for the project, e.g. mySettings.runsettings.
   
2. Modify the file based on the example below
   
   <?xml version="1.0" encoding="utf-8"?>  
   <RunSettings>
    <RunConfiguration>
      <DisableParallelization>True</DisableParallelization>
    </RunConfiguration>
    <InProcDataCollectionRunSettings>
      <InProcDataCollectors>
        <InProcDataCollector friendlyName="JetBrainsProfiler" uri="InProcDataCollector://JetBrains/JetBrainsProfiler/1.0" assemblyQualifiedName="<AQN>" codebase="<PATH>">
          <Configuration />
        </InProcDataCollector>
      </InProcDataCollectors>
    </InProcDataCollectionRunSettings>
   </RunSettings>
   
   Here
• <AQN>: an assembly qualified name that depends on a dotCover version. For dotCover 2018.1.1, it is: JetBrains.Common.UnitTesting.InProcDataCollector.GrouplessCoverageInProcDataCollector, JetBrains.Common.UnitTesting.InProcDataCollector, Version=112.0.0.0, Culture=neutral, PublicKeyToken=1010a0d8d6380325
• <PATH>: an absolute path to the JetBrains.Common.UnitTesting.InProcDataCollector.dll library which is a part of dotCover. For example:
  C:\Users\[YourUserName]\AppData\Local\JetBrains\Installations/JetBrains/Installations/dotCover12/JetBrains.Common.UnitTesting.InProcDataCollector.dll
  
  
3. Run coverage analysis from the command line with the additional /UseApi parameter.
   For example:
   
   dotCover.exe cover /TargetExecutable="C:\Program Files\dotnet\dotnet.exe" /TargetArguments="test -s C:\MyProject\mySettings.runsettings C:\MyProject\MyTests.csproj" /Output=snapshot.dcvr /UseApi
   
   
   

dotCover on TeamCity:

• You have a TeamCity server with installed dotCover 2018.1.1 or later.
• You have a .NET Core unit test project or use Visual Studio Tests build step.
• You want to perform coverage analysis of unit tests via dotCover.

To perform coverage analysis:

1. Create (or modify an existing) a .runsettings file for the project, e.g. mySettings.runsettings.
2. Modify the file based on the example below
   
   <?xml version="1.0" encoding="utf-8"?>  
   <RunSettings>
    <RunConfiguration>
      <DisableParallelization>True</DisableParallelization>
    </RunConfiguration>
    <InProcDataCollectionRunSettings>
      <InProcDataCollectors>
        <InProcDataCollector friendlyName="JetBrainsProfiler" uri="InProcDataCollector://JetBrains/JetBrainsProfiler/1.0" assemblyQualifiedName="<AQN>" codebase="PATH_TO_InProcDataCollector">
          <Configuration />
        </InProcDataCollector>
      </InProcDataCollectors>
    </InProcDataCollectionRunSettings>
   </RunSettings>
   
   Here
• <AQN>: an assembly qualified name that depends on a dotCover version. For dotCover 2018.1.1, it is: JetBrains.Common.UnitTesting.InProcDataCollector.GrouplessCoverageInProcDataCollector, JetBrains.Common.UnitTesting.InProcDataCollector, Version=112.0.0.0, Culture=neutral, PublicKeyToken=1010a0d8d6380325
  
3. On TeamCity server add “File content replacer” to Build Features to change PATH_TO_InProcDataCollector to %teamcity.tool.JetBrains.dotCover.CommandLineTools.DEFAULT%/JetBrains.Common.UnitTesting.InProcDataCollector.dll in mySettings.runsettings file:
   
   
   
   
4. Run coverage analysis in “.NET CLI(dotnet)” build step with “test” command type or in “Visual Studio Tests” build step. Expand Advanced options, set a path to mySettings.runsettings and add /UseApi to the Additional arguments: