`dotnet test` is inconsistent when it comes to showing the total number of unit tests at the end

Question

I have a solution with many projects. When I run dotnet test, it selects all my xUnit projects and seems to correctly execute all of them. But at the last line of what dotnet test prints, the number of test cases is inconsistent. Sometimes it shows 8, sometimes it shows 9.

The output when it shows 9:

C:...\SiLho\MREDotnetTest>dotnet test --logger html
Restore complete (0.6s)
 SharedLibraries succeeded (0.1s) → SharedLibraries\bin\Debug\net9.0\win-x64\SharedLibraries.dll
 TestProject1 succeeded (0.1s) → TestProject1\bin\Debug\net9.0\TestProject1.dll
 Connectors.Xlsx succeeded (0.1s) → Connectors\Xlsx\bin\Debug\net9.0\win-x64\Connectors.Xlsx.dll
 Connectors.Fusion succeeded (0.2s) → Connectors\Fusion\bin\Debug\net9.0\win-x64\Connectors.Fusion.dll
 VersionTracker succeeded (0.2s) → VersionTracker\bin\Debug\net9.0\win-x64\VersionTracker.dll
 Core succeeded (0.2s) → Core\bin\Debug\net9.0\win-x64\Core.dll
 Thisisalibrary succeeded (0.2s) → Thisisalibrary\bin\Debug\net9.0\win-x64\Thisisalibrary.dll
 VersionTracker.Tests succeeded (0.2s) → VersionTracker.Tests\bin\Debug\net9.0\win-x64\VersionTracker.Tests.dll
 Thisisalibrarytest succeeded (0.2s) → Thisisalibrarytest\bin\Debug\net9.0\win-x64\Thisisalibrarytest.dll
 Connectors.Tests.Fusion.Tests succeeded (0.2s) → Connectors.Tests\Fusion.Tests\bin\Debug\net9.0\win-x64\Connectors.Tests.Fusion.Tests.dll
 Mylibrary succeeded (0.3s) → Mylibrary\bin\Debug\net9.0\win-x64\Mylibrary.dll
 SharedLibraries.Tests succeeded (0.2s) → SharedLibraries.Tests\bin\Debug\net9.0\win-x64\SharedLibraries.Tests.dll
 Connectors.Tests.Xlsx.Tests succeeded (0.2s) → Connectors.Tests\Xlsx.Tests\bin\Debug\net9.0\win-x64\Connectors.Tests.Xlsx.Tests.dll
 Mylibrarytest succeeded (0.2s) → Mylibrarytest\bin\Debug\net9.0\win-x64\Mylibrarytest.dll
 Core.Tests succeeded (0.2s) → Core.Tests\bin\Debug\net9.0\win-x64\Core.Tests.dll
[xUnit.net 00:00:00.00] xUnit.net VSTest Adapter v3.1.5+1b188a7b0a (64-bit .NET 9.0.10)
[xUnit.net 00:00:00.10] Discovering: TestProject1
[xUnit.net 00:00:00.14] Discovered: TestProject1
[xUnit.net 00:00:00.16] Starting: TestProject1
[xUnit.net 00:00:00.20] Finished: TestProject1
[xUnit.net 00:00:00.00] xUnit.net VSTest Adapter v3.1.5+1b188a7b0a (64-bit .NET 9.0.10)
[xUnit.net 00:00:00.00] xUnit.net VSTest Adapter v3.1.5+1b188a7b0a (64-bit .NET 9.0.10)
[xUnit.net 00:00:00.00] xUnit.net VSTest Adapter v3.1.5+1b188a7b0a (64-bit .NET 9.0.10)
[xUnit.net 00:00:00.10] Discovering: Connectors.Tests.Fusion.Tests
[xUnit.net 00:00:00.10] Discovering: Thisisalibrarytest
[xUnit.net 00:00:00.10] Discovering: VersionTracker.Tests
[xUnit.net 00:00:00.13] Discovered: Connectors.Tests.Fusion.Tests
[xUnit.net 00:00:00.14] Discovered: Thisisalibrarytest
[xUnit.net 00:00:00.14] Discovered: VersionTracker.Tests
[xUnit.net 00:00:00.15] Starting: Connectors.Tests.Fusion.Tests
[xUnit.net 00:00:00.16] Starting: Thisisalibrarytest
[xUnit.net 00:00:00.16] Starting: VersionTracker.Tests
[xUnit.net 00:00:00.25] Finished: Connectors.Tests.Fusion.Tests
[xUnit.net 00:00:00.26] Finished: Thisisalibrarytest
[xUnit.net 00:00:00.25] Finished: VersionTracker.Tests
[xUnit.net 00:00:00.00] xUnit.net VSTest Adapter v3.1.5+1b188a7b0a (64-bit .NET 9.0.10)
[xUnit.net 00:00:00.00] xUnit.net VSTest Adapter v3.1.5+1b188a7b0a (64-bit .NET 9.0.10)
Html test results file : C:\Users\...\MREDotnetTest\TestProject1\TestResults\TestResult_lhott_IPHONEDEROMAIN_20251024_160659.html
[xUnit.net 00:00:00.00] xUnit.net VSTest Adapter v3.1.5+1b188a7b0a (64-bit .NET 9.0.10)
[xUnit.net 00:00:00.00] xUnit.net VSTest Adapter v3.1.5+1b188a7b0a (64-bit .NET 9.0.10)
[xUnit.net 00:00:00.14] Discovering: Core.Tests
[xUnit.net 00:00:00.12] Discovering: Connectors.Tests.Xlsx.Tests
[xUnit.net 00:00:00.12] Discovering: Mylibrarytest
[xUnit.net 00:00:00.11] Discovering: SharedLibraries.Tests
[xUnit.net 00:00:00.18] Discovered: Core.Tests
[xUnit.net 00:00:00.16] Discovered: Connectors.Tests.Xlsx.Tests
[xUnit.net 00:00:00.16] Discovered: Mylibrarytest
 TestProject1 test succeeded (1.5s)
[xUnit.net 00:00:00.20] Starting: Core.Tests
[xUnit.net 00:00:00.15] Discovered: SharedLibraries.Tests
[xUnit.net 00:00:00.20] Starting: Connectors.Tests.Xlsx.Tests
[xUnit.net 00:00:00.20] Starting: Mylibrarytest
[xUnit.net 00:00:00.19] Starting: SharedLibraries.Tests
[xUnit.net 00:00:00.31] Finished: Core.Tests
[xUnit.net 00:00:00.31] Finished: Connectors.Tests.Xlsx.Tests
[xUnit.net 00:00:00.31] Finished: Mylibrarytest
[xUnit.net 00:00:00.29] Finished: SharedLibraries.Tests
Html test results file : C:\Users\...\MREDotnetTest\Thisisalibrarytest\TestResults\TestResult_lhott_IPHONEDEROMAIN_20251024_160659.html
Html test results file : C:\Users\...\MREDotnetTest\VersionTracker.Tests\TestResults\TestResult_lhott_IPHONEDEROMAIN_20251024_160659.html
Html test results file : C:\Users\...\MREDotnetTest\Connectors.Tests\Fusion.Tests\TestResults\TestResult_lhott_IPHONEDEROMAIN_20251024_160659.html
 Thisisalibrarytest test succeeded (1.7s)
 VersionTracker.Tests test succeeded (1.7s)
 Connectors.Tests.Fusion.Tests test succeeded (1.7s)
 ConsoleApp succeeded (0.3s) → ConsoleApp\bin\Debug\net9.0\win-x64\ConsoleApp.dll
Html test results file : C:\Users\...\MREDotnetTest\Core.Tests\TestResults\TestResult_lhott_IPHONEDEROMAIN_20251024_160659.html
 Core.Tests test succeeded (1.5s)
Html test results file : C:\Users\...\MREDotnetTest\SharedLibraries.Tests\TestResults\TestResult_lhott_IPHONEDEROMAIN_20251024_160659.html
Html test results file : C:\Users\...\MREDotnetTest\Connectors.Tests\Xlsx.Tests\TestResults\TestResult_lhott_IPHONEDEROMAIN_20251024_160659.html
Html test results file : C:\Users\...\MREDotnetTest\Mylibrarytest\TestResults\TestResult_lhott_IPHONEDEROMAIN_20251024_160659.html
 Connectors.Tests.Xlsx.Tests test succeeded (1.6s)
 SharedLibraries.Tests test succeeded (1.6s)
 Mylibrarytest test succeeded (1.6s)
 ConsoleApp.Tests succeeded (0.2s) → ConsoleApp.Tests\bin\Debug\net9.0\win-x64\ConsoleApp.Tests.dll
[xUnit.net 00:00:00.00] xUnit.net VSTest Adapter v3.1.5+1b188a7b0a (64-bit .NET 9.0.10)
[xUnit.net 00:00:00.07] Discovering: ConsoleApp.Tests
[xUnit.net 00:00:00.11] Discovered: ConsoleApp.Tests
[xUnit.net 00:00:00.13] Starting: ConsoleApp.Tests
[xUnit.net 00:00:00.16] Finished: ConsoleApp.Tests
Html test results file : C:\Users\...\MREDotnetTest\ConsoleApp.Tests\TestResults\TestResult_lhott_IPHONEDEROMAIN_20251024_160700.html
 ConsoleApp.Tests test succeeded (1.0s)
Test summary: total: 9, failed: 0, succeeded: 9, skipped: 0, duration: 3.1s
Build succeeded in 4.1s

The output when it shows 8:

C:\...\MREDotnetTest>dotnet test --logger html
Restore complete (0.6s)
 SharedLibraries succeeded (0.1s) → SharedLibraries\bin\Debug\net9.0\win-x64\SharedLibraries.dll
 TestProject1 succeeded (0.1s) → TestProject1\bin\Debug\net9.0\TestProject1.dll
 VersionTracker succeeded (0.1s) → VersionTracker\bin\Debug\net9.0\win-x64\VersionTracker.dll
 Thisisalibrary succeeded (0.1s) → Thisisalibrary\bin\Debug\net9.0\win-x64\Thisisalibrary.dll
 Core succeeded (0.1s) → Core\bin\Debug\net9.0\win-x64\Core.dll
 Connectors.Xlsx succeeded (0.1s) → Connectors\Xlsx\bin\Debug\net9.0\win-x64\Connectors.Xlsx.dll
 VersionTracker.Tests succeeded (0.1s) → VersionTracker.Tests\bin\Debug\net9.0\win-x64\VersionTracker.Tests.dll
 Thisisalibrarytest succeeded (0.1s) → Thisisalibrarytest\bin\Debug\net9.0\win-x64\Thisisalibrarytest.dll
 Mylibrary succeeded (0.3s) → Mylibrary\bin\Debug\net9.0\win-x64\Mylibrary.dll
 Mylibrarytest succeeded (0.1s) → Mylibrarytest\bin\Debug\net9.0\win-x64\Mylibrarytest.dll
[xUnit.net 00:00:00.00] xUnit.net VSTest Adapter v3.1.5+1b188a7b0a (64-bit .NET 9.0.10)
[xUnit.net 00:00:00.07] Discovering: TestProject1
[xUnit.net 00:00:00.10] Discovered: TestProject1
[xUnit.net 00:00:00.00] xUnit.net VSTest Adapter v3.1.5+1b188a7b0a (64-bit .NET 9.0.10)
[xUnit.net 00:00:00.11] Starting: TestProject1
[xUnit.net 00:00:00.15] Finished: TestProject1
[xUnit.net 00:00:00.06] Discovering: VersionTracker.Tests
[xUnit.net 00:00:00.09] Discovered: VersionTracker.Tests
[xUnit.net 00:00:00.11] Starting: VersionTracker.Tests
[xUnit.net 00:00:00.15] Finished: VersionTracker.Tests
[xUnit.net 00:00:00.00] xUnit.net VSTest Adapter v3.1.5+1b188a7b0a (64-bit .NET 9.0.10)
Html test results file : C:\Users\...\MREDotnetTest\TestProject1\TestResults\TestResult_lhott_IPHONEDEROMAIN_20251024_160749.html
 TestProject1 test succeeded (1.0s)
[xUnit.net 00:00:00.07] Discovering: Mylibrarytest
[xUnit.net 00:00:00.10] Discovered: Mylibrarytest
[xUnit.net 00:00:00.12] Starting: Mylibrarytest
Html test results file : C:\Users\...\MREDotnetTest\VersionTracker.Tests\TestResults\TestResult_lhott_IPHONEDEROMAIN_20251024_160749.html
 Connectors.Fusion succeeded (0.1s) → Connectors\Fusion\bin\Debug\net9.0\win-x64\Connectors.Fusion.dll
 VersionTracker.Tests test succeeded (1.0s)
 Thisisalibrarytest test succeeded (1.0s)
[xUnit.net 00:00:00.16] Finished: Mylibrarytest
 ConsoleApp succeeded (0.1s) → ConsoleApp\bin\Debug\net9.0\win-x64\ConsoleApp.dll
 SharedLibraries.Tests succeeded (0.1s) → SharedLibraries.Tests\bin\Debug\net9.0\win-x64\SharedLibraries.Tests.dll
 Connectors.Tests.Xlsx.Tests succeeded (0.1s) → Connectors.Tests\Xlsx.Tests\bin\Debug\net9.0\win-x64\Connectors.Tests.Xlsx.Tests.dll
 Core.Tests succeeded (0.1s) → Core.Tests\bin\Debug\net9.0\win-x64\Core.Tests.dll
 Connectors.Tests.Fusion.Tests succeeded (0.1s) → Connectors.Tests\Fusion.Tests\bin\Debug\net9.0\win-x64\Connectors.Tests.Fusion.Tests.dll
 ConsoleApp.Tests succeeded (0.1s) → ConsoleApp.Tests\bin\Debug\net9.0\win-x64\ConsoleApp.Tests.dll
Html test results file : C:\Users\...\MREDotnetTest\Mylibrarytest\TestResults\TestResult_lhott_IPHONEDEROMAIN_20251024_160750.html
 Mylibrarytest test succeeded (1.0s)
[xUnit.net 00:00:00.00] xUnit.net VSTest Adapter v3.1.5+1b188a7b0a (64-bit .NET 9.0.10)
[xUnit.net 00:00:00.00] xUnit.net VSTest Adapter v3.1.5+1b188a7b0a (64-bit .NET 9.0.10)
[xUnit.net 00:00:00.00] xUnit.net VSTest Adapter v3.1.5+1b188a7b0a (64-bit .NET 9.0.10)
[xUnit.net 00:00:00.00] xUnit.net VSTest Adapter v3.1.5+1b188a7b0a (64-bit .NET 9.0.10)
[xUnit.net 00:00:00.07] Discovering: Connectors.Tests.Xlsx.Tests
[xUnit.net 00:00:00.06] Discovering: SharedLibraries.Tests
[xUnit.net 00:00:00.07] Discovering: Core.Tests
[xUnit.net 00:00:00.00] xUnit.net VSTest Adapter v3.1.5+1b188a7b0a (64-bit .NET 9.0.10)
[xUnit.net 00:00:00.07] Discovering: Connectors.Tests.Fusion.Tests
[xUnit.net 00:00:00.10] Discovered: Connectors.Tests.Xlsx.Tests
[xUnit.net 00:00:00.10] Discovered: SharedLibraries.Tests
[xUnit.net 00:00:00.10] Discovered: Core.Tests
[xUnit.net 00:00:00.12] Starting: Connectors.Tests.Xlsx.Tests
[xUnit.net 00:00:00.11] Starting: SharedLibraries.Tests
[xUnit.net 00:00:00.10] Discovered: Connectors.Tests.Fusion.Tests
[xUnit.net 00:00:00.12] Starting: Core.Tests
[xUnit.net 00:00:00.12] Starting: Connectors.Tests.Fusion.Tests
[xUnit.net 00:00:00.07] Discovering: ConsoleApp.Tests
[xUnit.net 00:00:00.15] Finished: Connectors.Tests.Xlsx.Tests
[xUnit.net 00:00:00.15] Finished: SharedLibraries.Tests
[xUnit.net 00:00:00.16] Finished: Core.Tests
[xUnit.net 00:00:00.15] Finished: Connectors.Tests.Fusion.Tests
[xUnit.net 00:00:00.11] Discovered: ConsoleApp.Tests
[xUnit.net 00:00:00.13] Starting: ConsoleApp.Tests
[xUnit.net 00:00:00.17] Finished: ConsoleApp.Tests
Html test results file : C:\Users\...\MREDotnetTest\SharedLibraries.Tests\TestResults\TestResult_lhott_IPHONEDEROMAIN_20251024_160750.html
Html test results file : C:\Users\...\MREDotnetTest\Connectors.Tests\Xlsx.Tests\TestResults\TestResult_lhott_IPHONEDEROMAIN_20251024_160750.html
Html test results file : C:\Users\...\MREDotnetTest\Core.Tests\TestResults\TestResult_lhott_IPHONEDEROMAIN_20251024_160750.html
 SharedLibraries.Tests test succeeded (1.0s)
 Connectors.Tests.Xlsx.Tests test succeeded (1.0s)
 Core.Tests test succeeded (1.0s)
Html test results file : C:\Users\...\MREDotnetTest\Connectors.Tests\Fusion.Tests\TestResults\TestResult_lhott_IPHONEDEROMAIN_20251024_160750.html
 Connectors.Tests.Fusion.Tests test succeeded (1.0s)
Html test results file : C:\Users\...\MREDotnetTest\ConsoleApp.Tests\TestResults\TestResult_lhott_IPHONEDEROMAIN_20251024_160750.html
 ConsoleApp.Tests test succeeded (1.0s)
Test summary: total: 8, failed: 0, succeeded: 8, skipped: 0, duration: 2.2s
Build succeeded in 3.1s

I need to have around a dozen projects in the solution for the bug to trigger, I cannot make a MRE with less projects. These projects can be completely empty (with empty test cases for the xUnit projects). They need to "call" each other in the .csproj (even though all the files are empty so technically they don't actually call each other).

I cannot reproduce on another computer that has everything set up the same except it has 64 GB RAM and a Ryzen 9.

For the record, I use --logger html but I don't think that has anything to do with the problem. What should I investigate? How can I get to the bottom of this?

Already checked:

• xUnit is up to date.
• I have the latest .NET version (9.0.306)
• Windows is up to date

Specs:

• AMD Ryzen 7 5800H with Radeon Graphics
• 32.0 GB RAM
• Windows 11, Version 10.0.26200 Build 26200
• BIOS: LENOVO HHCN24WW, 24/11/2021

MRE to reproduce (really, I apologize I can't make it smaller, the bug disappears when there are less files ... - it's a lot of files but they are all basically empty): https://github.com/JasonMendoza2008/MREDotnetTest

Proof:

• https://youtu.be/1Cyux7dAw5Y

Maybe to investigate?

• Why is there xUnit.net VSTest Adapter v3.1.5+1b188a7b0a (64-bit .NET 9.0.10) in the output? I only have 9.0.306:

PS C:\...> dotnet --list-sdks
9.0.306 [C:\Program Files\dotnet\sdk]

• I cannot reproduce the bug with: -m:1 but it is not really a solution .. using multiple cores speeds up the process so much (doesn't matter for the MRE, matters for a real monolith solution).