OnAutoInsert_EnterKey3 fails on Linux

[jaredpar]

When run on Linux the tests will fail with the following error:

   /home/jaredpar/code/roslyn/src/Compilers/Test/Core/Assert/AssertEx.cs(1012): error TESTERROR: 
      Microsoft.CodeAnalysis.LanguageServer.UnitTests.OnAutoInsert.OnAutoInsertTests.OnAutoInsert_EnterKey3(mutatingLspWorkspace: False) (1s 855ms): Error Message: Assert.NotNull() Failure: Value is
       null
      Stack Trace:
         at Roslyn.Test.Utilities.AssertEx.NotNull[T](T value) in /home/jaredpar/code/roslyn/src/Compilers/Test/Core/Assert/AssertEx.cs:line 1012
         at Microsoft.CodeAnalysis.LanguageServer.UnitTests.OnAutoInsert.AbstractOnAutoInsertTests.VerifyCSharpMarkupAndExpected(String characterTyped, String markup, String expected, Boolean mutati
      ngLspWorkspace, Boolean insertSpaces, Int32 tabSize, String languageName, WellKnownLspServerKinds serverKind, Boolean useVSCapabilities) in /home/jaredpar/code/roslyn/src/LanguageServer/Protoc
      olUnitTests/OnAutoInsert/AbstractOnAutoInsertTests.cs:line 55
         at Microsoft.CodeAnalysis.LanguageServer.UnitTests.OnAutoInsert.AbstractOnAutoInsertTests.VerifyCSharpMarkupAndExpected(String characterTyped, String markup, String expected, Boolean mutati
      ngLspWorkspace, Boolean insertSpaces, Int32 tabSize, String languageName, WellKnownLspServerKinds serverKind, Boolean useVSCapabilities) in /home/jaredpar/code/roslyn/src/LanguageServer/Protoc
      olUnitTests/OnAutoInsert/AbstractOnAutoInsertTests.cs:line 58
      --- End of stack trace from previous location ---