dotnet test does not find any tests if environment variable is set that ends with dll

Describe the bug

We use environment variables in some integration test solutions. During our testing we encountered a strange behavior of the dotnet test command. If you provide any environment variable using the -e, --environmentoption where the value ends on dll, the whole test scripts stops working and the cli does not find any tests anymore.

I assume that for some reason the cli interprets the ending dll as solution/project/library in which to search for tests instead of the given solution or project. Funny enough csproj or sln at the end of any environment variable does not cause any issues.

Command	Result
`dotnet test -t	OK
dotnet test -t -e foo=bar	OK
dotnet test -t -e foo=bardll	FAIL
dotnet test -t -e foodll=bar	OK
dotnet test -t -e foo=barsln	OK
dotnet test -t -e foo=barcsproj	OK

To Reproduce

1. Create a bare-bone test project
2. Run tests using dotnet test with any environment variable option whose value ends with dll
3. No tests will be found

Setup

dotnet new xunit -o Example.Tests
cd Example.Tests

Normal Behavior

dotnet test -t
# also this one is fine
dotnet test -t -e foo=bar

C:\Temp\tests\Example.Tests> dotnet test -t
  Determining projects to restore...
  All projects are up-to-date for restore.
  Example.Tests -> C:\Temp\tests\Example.Tests\bin\Debug\net6.0\Example.Tests.dll
Test run for C:\Temp\tests\Example.Tests\bin\Debug\net6.0\Example.Tests.dll (.NETCoreApp,Version=v6.0)
Microsoft (R) Test Execution Command Line Tool Version 17.1.0
Copyright (c) Microsoft Corporation.  All rights reserved.

The following Tests are available:
    Example.Tests.UnitTest1.Test1

Failing Cases

dotnet test -t -e foo=bardll

C:\Temp\tests\Example.Tests> dotnet test -t -e foo=bardll
Microsoft (R) Test Execution Command Line Tool Version 17.1.0
Copyright (c) Microsoft Corporation.  All rights reserved.

No test source files were specified.

Exceptions (if any)

Further technical details

.NET SDK (reflecting any global.json):
 Version:   6.0.203
 Commit:    a20feadf6d

Runtime Environment:
 OS Name:     Windows
 OS Version:  10.0.19044
 OS Platform: Windows
 RID:         win10-x64
 Base Path:   C:\Program Files\dotnet\sdk\6.0.203\

global.json file:
  Not found

Host:
  Version:      6.0.9
  Architecture: x64
  Commit:       163a63591c

.NET SDKs installed:
  3.1.423 [C:\Program Files\dotnet\sdk]
  5.0.214 [C:\Program Files\dotnet\sdk]
  5.0.402 [C:\Program Files\dotnet\sdk]
  5.0.408 [C:\Program Files\dotnet\sdk]
  6.0.200 [C:\Program Files\dotnet\sdk]
  6.0.203 [C:\Program Files\dotnet\sdk]

.NET runtimes installed:
  Microsoft.AspNetCore.All 2.1.30 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.App 2.1.30 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.1.20 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.1.29 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 5.0.11 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 5.0.17 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 6.0.2 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 6.0.5 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 6.0.9 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 2.1.30 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.1.20 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.1.29 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 5.0.11 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 5.0.17 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 6.0.2 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 6.0.5 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 6.0.9 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.WindowsDesktop.App 3.1.20 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 3.1.29 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 5.0.11 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 5.0.17 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 6.0.2 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 6.0.5 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 6.0.9 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

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  https://aka.ms/dotnet-download

Learn about .NET Runtimes and SDKs:
  https://aka.ms/dotnet/runtimes-sdk-info

[jcoeltjen]

Hi @MarcoRossignoli , this is currently not a blocking issue for us as we restructured our code in a way that we currently do not use the environment variable that caused issues anymore.

I am looking forward to trying the fix anyway. Thanks for the swift response and the quick PR!

[MarcoRossignoli]

Thanks @jcoeltjen for the quick response, the fix will be released on 7.0.200 version of the SDK won’t be shipped for 7.0.100 GA.