CMP0064

Recognize TEST as a operator for the if() command.

The TEST operator was added to the if() command to determine if a given test name was created by the add_test() command.

The OLD behavior for this policy is to ignore the TEST operator. The NEW behavior is to interpret the TEST operator.

This policy was introduced in CMake version 3.4. CMake version 3.15.7 warns when the policy is not set and uses OLD behavior. Use the cmake_policy() command to set it to OLD or NEW explicitly.