Fix tests on Mac

CONTRIBUTING.md

@@ -53,18 +53,19 @@ On Windows you can also attach from Visual Studio 2017 (Debug | Attach To Proces
 3. Use the `Launch Extension` launch option.
 
 ### Unit Tests
-1. Run the Unit Tests in VS Code via the `Launch Language Server Tests`.
-2. On Windows Open PLS.sln solution in Visual Studio 2017 and run its tests.
-3. Run `dotnet test` from Terminal.
-4. Install .NET Core Test Explorer for VS Code, open src folder in VS Code and run tests.
+To run unit tests, do one of the following:
+- Run the Unit Tests in the [VS Code Python Extension](https://github.com/Microsoft/vscode-python) project via the `Launch Language Server Tests`.
+- On Windows: open PLS.sln solution in Visual Studio 2017 and run tests from the Test Explorer.
+- Run `dotnet test` from Terminal.
+- Install C# extension and .NET Core Test Explorer for VS Code, open src folder in VS Code and run tests.
 
 NOTE: Language Server does not automatically discover Python installations on various operating systems.
-At run time path to the Python interpreter is provided by the client application. Therefore you may not
-be able to run tests if test code is unable to find the local Python installation as it only has basic
-capabilities for the discovery. Refer to the discovery code for 
+At run time path to the Python interpreter is provided by the client application. Test environment does
+make an attempt to discover Python installation, but in case it is unable to find Python you will not
+be able to run tests. Refer to the Python interpreter discovery code for 
 [Windows](https://github.com/Microsoft/python-language-server/blob/master/src/Analysis/Engine/Test/WindowsPythonInstallPathResolver.cs) 
 and [*nix](https://github.com/Microsoft/python-language-server/blob/master/src/Analysis/Engine/Test/UnixPythonInstallPathResolver.cs)
 
 
 ### Coding Standards
-Import Formatting.vssettings into Visual Studio
+Import `Formatting.vssettings` into Visual Studio or use `.editorconfig`.