get_filename_component: Tests now check for proper CACHE usage.

The RunCMake.get_filename_component test was improved to assert that
each test variable outputted by get_filename_component is or is not
a cache variable, as per the particular test.

Signed-off-by: James Johnston <johnstonj.public@codenest.com>

Tests/RunCMake/get_filename_component/CMakeLists.txt

-cmake_minimum_required(VERSION 2.8.4)
+cmake_minimum_required(VERSION 3.3)
 project(${RunCMake_TEST} NONE)
 include(${RunCMake_TEST}.cmake)

Tests/RunCMake/get_filename_component/KnownComponents.cmake

+# Assertion macro
 macro(check desc actual expect)
   if(NOT "x${actual}" STREQUAL "x${expect}")
     message(SEND_ERROR "${desc}: got \"${actual}\", not \"${expect}\"")
   endif()
 endmacro()
 
+# General test of all component types given an absolute path.
 set(filename "/path/to/filename.ext.in")
 set(expect_DIRECTORY "/path/to")
 set(expect_NAME "filename.ext.in")
@@ -13,14 +15,19 @@ set(expect_PATH "/path/to")
 foreach(c DIRECTORY NAME EXT NAME_WE PATH)
   get_filename_component(actual_${c} "${filename}" ${c})
   check("${c}" "${actual_${c}}" "${expect_${c}}")
+  list(APPEND non_cache_vars actual_${c})
 endforeach()
 
+# Test Windows paths with DIRECTORY component and an absolute Windows path.
 get_filename_component(test_slashes "c:\\path\\to\\filename.ext.in" DIRECTORY)
 check("DIRECTORY from backslashes" "${test_slashes}" "c:/path/to")
+list(APPEND non_cache_vars test_slashes)
 
 get_filename_component(test_winroot "c:\\filename.ext.in" DIRECTORY)
 check("DIRECTORY in windows root" "${test_winroot}" "c:/")
+list(APPEND non_cache_vars test_winroot)
 
+# Test finding absolute paths.
 get_filename_component(test_absolute "/path/to/a/../filename.ext.in" ABSOLUTE)
 check("ABSOLUTE" "${test_absolute}" "/path/to/filename.ext.in")
 
@@ -29,10 +36,36 @@ check("ABSOLUTE .. in root" "${test_absolute}" "/path/to/filename.ext.in")
 get_filename_component(test_absolute "c:/../path/to/filename.ext.in" ABSOLUTE)
 check("ABSOLUTE .. in windows root" "${test_absolute}" "c:/path/to/filename.ext.in")
 
+list(APPEND non_cache_vars test_absolute)
+
+# Test CACHE parameter for most component types.
 get_filename_component(test_cache "/path/to/filename.ext.in" DIRECTORY CACHE)
 check("CACHE 1" "${test_cache}" "/path/to")
+# Make sure that the existing CACHE entry from previous is honored:
 get_filename_component(test_cache "/path/to/other/filename.ext.in" DIRECTORY CACHE)
 check("CACHE 2" "${test_cache}" "/path/to")
 unset(test_cache CACHE)
 get_filename_component(test_cache "/path/to/other/filename.ext.in" DIRECTORY CACHE)
 check("CACHE 3" "${test_cache}" "/path/to/other")
+
+list(APPEND cache_vars test_cache)
+
+# Test that ONLY the expected cache variables were created.
+get_cmake_property(current_cache_vars CACHE_VARIABLES)
+get_cmake_property(current_vars VARIABLES)
+
+foreach(thisVar ${cache_vars})
+  if(NOT thisVar IN_LIST current_cache_vars)
+    message(SEND_ERROR "${thisVar} expected in cache but was not found.")
+  endif()
+endforeach()
+
+foreach(thisVar ${non_cache_vars})
+  if(thisVar IN_LIST current_cache_vars)
+    message(SEND_ERROR "${thisVar} unexpectedly found in cache.")
+  endif()
+  if(NOT thisVar IN_LIST current_vars)
+    # Catch likely typo when appending to non_cache_vars:
+    message(SEND_ERROR "${thisVar} not found in regular variable list.")
+  endif()
+endforeach()