[interpreter] Configure the flags for InterOp correctly

Also moves the addition of `CppInterOpUnitTests` to the build chain, from metacling, to the interpreter cmake

Author: aaronj0

core/metacling/src/CMakeLists.txt

@@ -119,10 +119,6 @@ ROOT_LINKER_LIBRARY(Cling
 # When these two link at the same time, they can exhaust the RAM on many machines, since they both link against llvm.
 add_dependencies(Cling rootcling_stage1)
 
-if(testing)
-  set_target_properties(CppInterOpUnitTests PROPERTIES EXCLUDE_FROM_ALL OFF)
-endif()
-
 if(MSVC)
   set_target_properties(Cling PROPERTIES WINDOWS_EXPORT_ALL_SYMBOLS TRUE)
   set(cling_exports ${cling_exports}

interpreter/CMakeLists.txt

@@ -523,6 +523,17 @@ set(CPPINTEROP_INCLUDE_DIRS
   CACHE STRING "CppInterOp include directories.")
 
 #---Set InterOp to build on Cling, this can be toggled to use Clang-REPL-------------------------------------------------------
-set(CPPINTEROP_USE_CLING ON BOOL "Use Cling as backend")
+set(CPPINTEROP_USE_CLING ON CACHE BOOL "" FORCE)
+set(CPPINTEROP_USE_REPL OFF CACHE BOOL "" FORCE)
+
+#---Disable testing on InterOp if ROOT's testing is OFF (InterOp tests are enabled by default) -------------------------------------------------------
+if(testing)
+  set(CPPINTEROP_ENABLE_TESTING ON CACHE BOOL "" FORCE)
+else()
+  set(CPPINTEROP_ENABLE_TESTING OFF CACHE BOOL "")
+endif()
 
 add_subdirectory(CppInterOp)
+if(testing)
+  set_target_properties(CppInterOpUnitTests PROPERTIES EXCLUDE_FROM_ALL OFF)
+endif()