Marks a target as only being required for tests.

ecm_mark_as_test(<target1> [<target2> [...]])

This will cause the specified targets to not be built unless either BUILD_TESTING is set to ON or the user invokes the buildtests target.

BUILD_TESTING is created as a cache variable by the CTest module and by the KDECMakeSettings module.

Since pre-1.0.0.