include(RunCMake)
+# Isolate test cases from caller's environment.
+set(ENV{CMAKE_PREFIX_PATH} "")
+set(ENV{CMAKE_APPBUNDLE_PATH} "")
+set(ENV{CMAKE_FRAMEWORK_PATH} "")
+
run_cmake(FindPkgConfig_NO_PKGCONFIG_PATH)
run_cmake(FindPkgConfig_PKGCONFIG_PATH)
run_cmake(FindPkgConfig_PKGCONFIG_PATH_NO_CMAKE_PATH)