Added a command factory where you can fix the output parameters that will flow to the commands, like configuration, outputpath and in the future, framework, runtime and base path.

test/dotnet-test.UnitTests/GivenATestRunner.cs

@@ -41,7 +41,7 @@ namespace Microsoft.Dotnet.Tools.Test.Tests
                 $"dotnet-{_runner}",
                 _testRunnerArguments,
                 new NuGetFramework("DNXCore", Version.Parse("5.0")),
-                Constants.DefaultConfiguration)).Returns(_commandMock.Object).Verifiable();
+                null)).Returns(_commandMock.Object).Verifiable();
         }
 
         [Fact]