Initial commit of PIO Unit Testing

platformio/exception.py

@@ -292,3 +292,12 @@ class DebugSupportError(PlatformioException):
 class DebugInvalidOptions(PlatformioException):
 
     pass
+
+
+class TestDirNotExists(PlatformioException):
+
+    MESSAGE = "A test folder '{0}' does not exist.\nPlease create 'test' "\
+              "directory in project's root and put a test set.\n"\
+              "More details about Unit "\
+              "Testing: http://docs.platformio.org/page/plus/"\
+              "unit-testing.html"