"The process cannot access the file, because it is being used by another process" error during attempt to collect coverage

[AntiPasha]

The error message for MSBuild intergration

C:\Users\xxx\.nuget\packages\coverlet.msbuild\2.8.1\build\coverlet.msbuild.targets(36,5): error : One or more errors occurred. (The process cannot access the file 'D:\Work\xxx\yyy\test\yyy.Tests\bin\Debug\netcoreapp2.1\zzz.Dto.dll' because it is being used by another process.)[D:\Work\xxx\yyy\test\yyy.Tests\yyy.Tests.csproj]
C:\Users\xxx\.nuget\packages\coverlet.msbuild\2.8.1\build\coverlet.msbuild.targets(36,5): error :    at Coverlet.Core.Helpers.RetryHelper.Do[T](Func`1 action, Func`1 backoffStrategy, Int32 maxAttemptCount) in c:\git\coverletToRelease\src\coverlet.core\Helpers\RetryHelper.cs:line 59 [D:\Work\xxx\yyy\test\yyy.Tests\yyy.Tests.csproj]
C:\Users\xxx\.nuget\packages\coverlet.msbuild\2.8.1\build\coverlet.msbuild.targets(36,5): error :    at Coverlet.Core.Helpers.RetryHelper.Retry(Action action, Func`1 backoffStrategy, Int32 maxAttemptCount) in c:\git\coverletToRelease\src\coverlet.core\Helpers\RetryHelper.cs:line 28 [D:\Work\xxx\yyy\test\yyy.Tests\yyy.Tests.csproj]
C:\Users\xxx\.nuget\packages\coverlet.msbuild\2.8.1\build\coverlet.msbuild.targets(36,5): error :    at Coverlet.Core.Helpers.InstrumentationHelper.RestoreOriginalModule(String module, String identifier) in c:\git\coverletToRelease\src\coverlet.core\Helpers\InstrumentationHelper.cs:line 219 [D:\Work\xxx\yyy\test\yyy.Tests\yyy.Tests.csproj]
C:\Users\xxx\.nuget\packages\coverlet.msbuild\2.8.1\build\coverlet.msbuild.targets(36,5): error :    at Coverlet.Core.Coverage.GetCoverageResult() in c:\git\coverletToRelease\src\coverlet.core\Coverage.cs:line 219 [D:\Work\xxx\yyy\test\yyy.Tests\yyy.Tests.csproj]
C:\Users\xxx\.nuget\packages\coverlet.msbuild\2.8.1\build\coverlet.msbuild.targets(36,5): error :    at Coverlet.MSbuild.Tasks.CoverageResultTask.Execute() in c:\git\coverletToRelease\src\coverlet.msbuild.tasks\CoverageResultTask.cs:line 113 [D:\Work\xxx\yyy\test\yyy.Tests\yyy.Tests.csproj]

The same behavior for VSTest integration

---> (Inner Exception #1) System.IO.IOException: The process cannot access the file 'D:\Work\xxx\yyy\test\yyy.Tests\bin\Debug\netcoreapp2.1\zzz.dll' because it is being used by another process.
   at System.IO.FileSystem.CopyFile(String sourceFullPath, String destFullPath, Boolean overwrite)
   at System.IO.File.Copy(String sourceFileName, String destFileName, Boolean overwrite)
   at Coverlet.Core.Helpers.FileSystem.Copy(String sourceFileName, String destFileName, Boolean overwrite) in c:\git\coverletToRelease\src\coverlet.core\Helpers\FileSystem.cs:line 33
   at Coverlet.Core.Helpers.InstrumentationHelper.<>c__DisplayClass10_0.<RestoreOriginalModule>b__0() in c:\git\coverletToRelease\src\coverlet.core\Helpers\InstrumentationHelper.cs:line 215
   at Coverlet.Core.Helpers.RetryHelper.<>c__DisplayClass0_0.<Retry>b__0() in c:\git\coverletToRelease\src\coverlet.core\Helpers\RetryHelper.cs:line 26
   at Coverlet.Core.Helpers.RetryHelper.Do[T](Func`1 action, Func`1 backoffStrategy, Int32 maxAttemptCount) in c:\git\coverletToRelease\src\coverlet.core\Helpers\RetryHelper.cs:line 52<---

It happens all the time, when I try to collect coverage for xunit test projects (with NUnit everything works fine suddenly) using default commands, like dotnet test --collect:"XPlat Code Coverage" or dotnet test /p:CollectCoverage=true

Adding -nr:false -m:1 arguments to MSBuild didn't help, as well as running commands with separate csproj file. I've used the latest versions of coverlet, xunit and Microsoft.NET.Test.Sdk packages

<PackageReference Include="coverlet.collector" Version="1.2.1">
  <PrivateAssets>all</PrivateAssets>
  <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
</PackageReference>
<PackageReference Include="coverlet.msbuild" Version="2.8.1">
  <PrivateAssets>all</PrivateAssets>
  <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
</PackageReference>
<PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.6.1" />
<PackageReference Include="Moq" Version="4.14.1" />
<PackageReference Include="xunit" Version="2.4.1" />
<PackageReference Include="xunit.runner.visualstudio" Version="2.4.1">
  <PrivateAssets>all</PrivateAssets>
  <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
</PackageReference>

Installed SDKs are below

.NET Core SDK (reflecting any global.json):
 Version:   3.1.202
 Commit:    6ea70c8dca

Runtime Environment:
 OS Name:     Windows
 OS Version:  10.0.18363
 OS Platform: Windows
 RID:         win10-x64
 Base Path:   C:\Program Files\dotnet\sdk\3.1.202\

Host (useful for support):
  Version: 3.1.4
  Commit:  0c2e69caa6

.NET Core SDKs installed:
  2.1.806 [C:\Program Files\dotnet\sdk]
  3.1.202 [C:\Program Files\dotnet\sdk]

.NET Core runtimes installed:
  Microsoft.AspNetCore.All 2.1.18 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.2.8 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.App 2.1.18 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.2.8 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.1.4 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 2.1.18 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.2.8 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.1.4 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.WindowsDesktop.App 3.1.4 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

Migrated from comments of 725 issue

[AntiPasha]

I've collected some events using Process Monitor, there no processes, except dotnet.exe and testhost.exe, accessing the file. During usual test run (without coverage) there is only file open, query information and locking file with only readers by testhost.exe.
When coverage is run, there are a file reading, writing and locking file with only readers by both processes. After file is locked by testhost.exe, dotnet.exe is returning a sharing violation result when attempt to use a file for generic read and write. It seems that both processes have something like a race condition, when file is locked for reading by one process and second process attempts to access it with read/write access.

Attached two files with events, first one for run with /p:CollectCoverage=true, second one with regular dotnet test. Attempt to run with --collect:"XPlat Code Coverage" shows the same behavior with msbuild integration
coverlet_msbuild.xlsx
dotnet.test.xlsx

[MarcoRossignoli]

Can you try only with collectors and enable verbose logging and attach logs(before check if there are sensitive data inside) https://github.com/coverlet-coverage/coverlet/blob/master/Documentation/Troubleshooting.md#collectors-integration?
I want to understand if vstest plat logging show some contention exception.

[AntiPasha]

Hi, please find verbose log for collectors attached. Thanks for your patience
log.host.20-05-29_01-00-26_57408_4.txt
log.txt
log.datacollector.20-05-29_01-00-25_75553_4.txt

[MarcoRossignoli]

Thanks

[MarcoRossignoli]

I cannot repro and without stack trace of thread that blocks files it's hard to understand the reason, I've got a temporary idea to try, we could avoid to raise error in case of issue during file restoring, so at least you can get a coverage file output. Could work for the moment?The only drawback is that the files inside bin/debug will remain instrumented and so no more usable for further test run.

[MarcoRossignoli]

That errors happens at the end of all coverage when we copy back original(non instrumented) files, but at that time coverage data are correctly gathered.

[MarcoRossignoli]

@AntiPasha I'm working on a workaround/solution, can you try with this package(collectors driver dotnet test --collect:"XPlat Code Coverage")

nuget feed source https://f.feedz.io/marcorossignoli/coverletunofficial/nuget/index.json
package version 1.3.1-preview.6.g1f7fe02d13

This is the feed I use for preview/investigation.

Branch master...MarcoRossignoli:issue857

[AntiPasha]

@MarcoRossignoli Thanks a lot for the update, I've tried your package and it seems to work fine, I didn't seen any exceptions, report is generated in random folder under TestResults, but in cobertura format. I thought that json is default one, because I didn't use any settings

[MarcoRossignoli]

For collector the default one is cobertura as explained in the guide

[MarcoRossignoli]

If you confirm that amend works well I can merge and you can use nightly build until next official release