FindGTK2: Add unit test to check variables when run twice

Tests/RunCMake/CMakeLists.txt

@@ -255,6 +255,11 @@ if(PKG_CONFIG_FOUND)
   add_RunCMake_test(FindPkgConfig)
 endif()
 
+find_package(GTK2 QUIET)
+if (GTK2_FOUND)
+  add_RunCMake_test(FindGTK2)
+endif()
+
 if("${CMAKE_GENERATOR}" MATCHES "Visual Studio")
   add_RunCMake_test(include_external_msproject)
   if("${CMAKE_GENERATOR}" MATCHES "Visual Studio ([789]|10)" AND NOT CMAKE_VS_DEVENV_COMMAND)

Tests/RunCMake/FindGTK2/CMakeLists.txt

@@ -0,0 +1,3 @@
+cmake_minimum_required(VERSION 3.5)
+project(${RunCMake_TEST} NONE)
+include(${RunCMake_TEST}.cmake)

Tests/RunCMake/FindGTK2/FindGTK2RunTwice.cmake

@@ -0,0 +1,21 @@
+cmake_minimum_required(VERSION 3.7)
+project(testFindGTK2 C)
+
+# First call
+find_package(GTK2 REQUIRED)
+
+# Backup variables
+set(GTK2_LIBRARIES_BAK ${GTK2_LIBRARIES})
+set(GTK2_TARGETS_BAK ${GTK2_TARGETS})
+
+# Second call
+find_package(GTK2 REQUIRED)
+
+# Check variables
+if(NOT "${GTK2_LIBRARIES_BAK}" STREQUAL "${GTK2_LIBRARIES}")
+  message(SEND_ERROR "GTK2_LIBRARIES is different:\nbefore: ${GTK2_LIBRARIES_BAK}\nafter:  ${GTK2_LIBRARIES}")
+endif()
+
+if(NOT "${GTK2_TARGETS_BAK}" STREQUAL "${GTK2_TARGETS}")
+  message(SEND_ERROR "GTK2_TARGETS is different:\nbefore: ${GTK2_TARGETS_BAK}\nafter:  ${GTK2_TARGETS}")
+endif()

Tests/RunCMake/FindGTK2/RunCMakeTest.cmake

@@ -0,0 +1,3 @@
+include(RunCMake)
+
+run_cmake(FindGTK2RunTwice)