[CMake] ctest & config type

[Clinton Stimpson]

I have a ctest script with a
set(CTEST_BUILD_CONFIGURATION "Release")

And in a CMakeLists.txt file I've got an
add_test(Foo ${CMAKE_CTEST_COMMAND}
    -C \${CTEST_CONFIGURATION_TYPE}
    --build-and-test  .... etc... )


But when ctest_test() is called in my ctest script, 
CTEST_CONFIGURATION_TYPE is empty, which makes my test fail.
Am I supposed to run ctest with the -C flag instead of trying to specify 
it in the script?
If so, then what's the point of having CTEST_BUILD_CONFIGURATION?

Clint