XUnit2Runner doesn't respect ParallelismOption.None

[kcamp]

What You Are Seeing?

XUnit2 is not respecting ParallelismOption.None

What is Expected?

The XUnit tool command should include the -parallel none when it's specified.

What version of Cake are you using?

0.25

Are you running on a 32 or 64 bit system?

64

What environment are you running on? Windows? Linux? Mac?

Windows

Are you running on a CI Server? If so, which one?

N/A

How Did You Get This To Happen? (Steps to Reproduce)

In consideration of this sample set of tests..

public sealed class SomeClass
{
    [Fact]
    public void OneShouldBeOne()
    {
        Thread.Sleep(5000);
        "one".Should().Be("one");
    }

    [Fact]
    public void TwoShouldBeTwo()
    {
        Thread.Sleep(5000);
        2.Should().Be(2);
    }
}

public sealed class AnotherClass
{
    [Fact]
    public void ThreeShouldBeThree()
    {
        Thread.Sleep(5000);
        3.Should().Be(3);
    }
}

When running this assembly with the task (following) I would expect the elapsed time of the tests to be 15 seconds.

XUnit2(
    assm,
    new XUnit2Settings
    {
        NoAppDomain = false,
        ShadowCopy = false,
        Parallelism = ParallelismOption.None
    });

Instead, it executes in ~10 seconds, indicating some degree of parallelism is at play.

Reading the docs at https://xunit.github.io/docs/running-tests-in-parallel.html

-parallel option 
Allows the user to specify which kinds of parallelization should be allowed for the test run. The valid option values are:
**none** Turns off all parallelization
**collections** Parallelizes collections, not assemblies
**assemblies** Parallelizes assemblies, not collections
**all** Parallelizes both collections and assemblies

The default value is collections. 

I think this last bit (defaulting to collections)is where our bug is coming into play; by suppressing the -parallel none, we're accepting the runner default.

Running that same set of tests again, manually from the CLI (below) to explicitly add the none flag gives execution time of ~15 seconds, as expected.

C:\git\sample-test-artifact> & "C:/git/sample-test-artifact/tools/xunit.runner.console.2.3.1/tools/net452/xunit.console.exe" "C:/git/sample-test-artifact/ArtifactTest/TestDiscovery.Fakes/bin/Debug/TestDiscovery.Fakes.dll" -noshadow -nunit "C:/git/sample-test-artifact/nunitTestResults/XUnitResults.xml" -parallel none

Output Log

C:\git\sample-test-artifact> .\build.ps1 -verbosity diagnostic                                                                                                                         
Preparing to run build script...                                                                                                                                                       
Running build script...                                                                                                                                                                
<snip>                                                                                                                                                                                                    
Found package 'xunit.runner.console 2.3.1' in 'C:/git/sample-test-artifact/tools'.                                                                                                     
Package xunit.runner.console.2.3.1 has already been installed.                                                                                                                         
Successfully installed 'xunit.runner.console 2.3.1' to C:/git/sample-test-artifact/tools                                                                                               
Executing nuget actions took 34.68 ms                                                                                                                                                  
<snip>                                                                                                                                   
Compiling build script...                                                                                                                                                              
                                                                                                                                                                                       
========================================                                                                                                                                               
Run-Tests                                                                                                                                                                              
========================================                                                                                                                                               
Executing task: Run-Tests                                                                                                                                                              
Executing: "C:/git/sample-test-artifact/tools/xunit.runner.console.2.3.1/tools/net452/xunit.console.exe" "C:/git/sample-test-artifact/ArtifactTest/TestDiscovery.Fakes/bin/Debug/TestDi
ery.Fakes.dll" -noshadow -nunit "C:/git/sample-test-artifact/nunitTestResults/XUnitResults.xml"                                                                                        
xUnit.net Console Runner (64-bit Desktop .NET 4.0.30319.42000)                                                                                                                         
  Discovering: TestDiscovery.Fakes                                                                                                                                                     
  Discovered:  TestDiscovery.Fakes                                                                                                                                                     
  Starting:    TestDiscovery.Fakes                                                                                                                                                     
  Finished:    TestDiscovery.Fakes                                                                                                                                                     
=== TEST EXECUTION SUMMARY ===                                                                                                                                                         
   TestDiscovery.Fakes  Total: 3, Errors: 0, Failed: 0, Skipped: 0, Time: 10.576s                                                                                                      
Finished executing task: Run-Tests                                                                                                                                                     
                                                                                                                                                                                       
========================================                                                                                                                                               
Default                                                                                                                                                                                
========================================                                                                                                                                               
Executing task: Default                                                                                                                                                                
Finished executing task: Default                                                                                                                                                       
                                                                                                                                                                                       
Task                          Duration                                                                                                                                                 
--------------------------------------------------                                                                                                                                     
Run-Tests                     00:00:11.3077021                                                                                                                                         
Default                       00:00:00.0019559                                                                                                                                         
--------------------------------------------------                                                                                                                                     
Total:                        00:00:11.3096580                                                                                                                                         

[kcamp]

I will have a PR for this shortly

[devlead]

Fixed by #2040