[CMake][NFC] Simplify cmake code for test fixtures.

Author: hageboeck

cmake/modules/RootMacros.cmake

@@ -1652,18 +1652,14 @@ function(ROOT_ADD_TEST test)
     set_tests_properties(${test} PROPERTIES LABELS "${ARG_LABELS}")
   endif()
 
-  if(ARG_PYTHON_DEPS)
-    foreach(python_dep ${ARG_PYTHON_DEPS})
-      if(NOT TEST test-import-${python_dep})
-        add_test(NAME test-import-${python_dep} COMMAND ${PYTHON_EXECUTABLE_Development_Main} -c "import ${python_dep}")
-        set_tests_properties(test-import-${python_dep} PROPERTIES FIXTURES_SETUP requires_${python_dep})
-      endif()
-      list(APPEND fixtures "requires_${python_dep}")
-    endforeach()
-    if(fixtures)
-      set_tests_properties(${test} PROPERTIES FIXTURES_REQUIRED "${fixtures}")
+  foreach(python_dep ${ARG_PYTHON_DEPS})
+    set(fixture_name requires_${python_dep})
+    set_property(TEST ${test} APPEND PROPERTY FIXTURES_REQUIRED ${fixture_name})
+    if(NOT TEST test-import-${python_dep})
+      add_test(NAME test-import-${python_dep} COMMAND ${PYTHON_EXECUTABLE_Development_Main} -c "import ${python_dep}")
+      set_tests_properties(test-import-${python_dep} PROPERTIES FIXTURES_SETUP ${fixture_name})
     endif()
-  endif()
+  endforeach()
 
   if(ARG_RUN_SERIAL)
     set_property(TEST ${test} PROPERTY RUN_SERIAL true)