I created a configuration named Test via Visual Studio which currently just takes all of DEBUG settings, however I employ compiler conditions to determine some specific acti
Note that when 'inside visual studio', the $(Configuration) and $(Platform) are always set by VS using the Configuration Manager stuff in the dropdowns at the top. Whereas if you want to set these values using msbuild from the command line, you must pass in the values explicitly (as in @MarkBiek's answer).
(Most VS project templates will 'default in' a value for Configuration/Platform, so that you can use the command-line MSBuild without specifying these values explicitly. This is good, but makes these two useful/common properties appear a little more magical/weird than they actually are.)