From 39cb35b1345e2d3878bcde7304a1c91c0281f5c1 Mon Sep 17 00:00:00 2001
From: Laurent Rineau <laurent.rineau@cgal.org>
Date: Tue, 31 Oct 2017 13:06:16 +0100
Subject: [PATCH] Avoid CMake errors with CMake<=3.4

---
 .../Arrangement_on_surface_2/cgal_test.cmake  | 30 +++++++++++++------
 CMakeLists.txt                                |  4 +++
 Installation/CMakeLists.txt                   |  5 +++-
 3 files changed, 29 insertions(+), 10 deletions(-)

diff --git a/Arrangement_on_surface_2/test/Arrangement_on_surface_2/cgal_test.cmake b/Arrangement_on_surface_2/test/Arrangement_on_surface_2/cgal_test.cmake
index 44d338e1a4e..9bff34826c6 100644
--- a/Arrangement_on_surface_2/test/Arrangement_on_surface_2/cgal_test.cmake
+++ b/Arrangement_on_surface_2/test/Arrangement_on_surface_2/cgal_test.cmake
@@ -156,18 +156,22 @@ function(cgal_arr_2_add_target exe_name source_file)
   target_compile_options(${name} PRIVATE ${flags})
   cgal_debug_message(STATUS "#      -> target ${name} with TESTSUITE_CXXFLAGS: ${flags}")
 
-  add_test(NAME "compilation_of__${name}"
-    COMMAND ${TIME_COMMAND} "${CMAKE_COMMAND}" --build "${CMAKE_BINARY_DIR}" --target "${name}")
-  set_property(TEST "compilation_of__${name}"
-    APPEND PROPERTY LABELS "${PROJECT_NAME}")
+  if(BUILD_TESTING)
+    add_test(NAME "compilation_of__${name}"
+      COMMAND ${TIME_COMMAND} "${CMAKE_COMMAND}" --build "${CMAKE_BINARY_DIR}" --target "${name}")
+    set_property(TEST "compilation_of__${name}"
+      APPEND PROPERTY LABELS "${PROJECT_NAME}")
+  endif(BUILD_TESTING)
 
   # Add a compatibility-mode with the shell script `cgal_test_base`
   if(NOT TARGET ${exe_name})
     create_single_source_cgal_program( "${source_file}" NO_TESTING)
-    add_test(NAME "compilation_of__${exe_name}"
-      COMMAND ${TIME_COMMAND} "${CMAKE_COMMAND}" --build "${CMAKE_BINARY_DIR}" --target "${exe_name}")
-    set_property(TEST "compilation_of__${exe_name}"
-      APPEND PROPERTY LABELS "${PROJECT_NAME}")
+    if(BUILD_TESTING)
+      add_test(NAME "compilation_of__${exe_name}"
+        COMMAND ${TIME_COMMAND} "${CMAKE_COMMAND}" --build "${CMAKE_BINARY_DIR}" --target "${exe_name}")
+      set_property(TEST "compilation_of__${exe_name}"
+        APPEND PROPERTY LABELS "${PROJECT_NAME}")
+    endif(BUILD_TESTING)
   endif()
 endfunction()
 
@@ -180,11 +184,17 @@ endfunction()
 function(run_test_with_flags)
   # ${ARGV0} - executable name
   # ${ARGV1} - test substring name
+  if(NOT BUILD_TESTING)
+    return()
+  endif()
   cgal_debug_message(STATUS "# run_test_with_flags(${ARGN})")
   cgal_add_test(${ARGV0}_${suffix} ${ARGV0} ${ARGV0}.${ARGV1})
 endfunction()
 
 function(run_test_alt name datafile)
+  if(NOT BUILD_TESTING)
+    return()
+  endif()
   if(suffix)
     set(name ${name}_${suffix})
   endif()
@@ -220,7 +230,9 @@ function(compile_and_run)
   cgal_debug_message(STATUS "# compile_and_run(${ARGN})")
 #  message("   successful compilation of ${name}")
   cgal_arr_2_add_target(${name} ${name}.cpp)
-  cgal_add_test(${name})
+  if(BUILD_TESTING)
+    cgal_add_test(${name})
+  endif()
 endfunction()
 
 function(execute_commands_old_structure data_dir traits_type_name)
diff --git a/CMakeLists.txt b/CMakeLists.txt
index d36a83c631f..6c702f30227 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -17,6 +17,10 @@ message( "== CMake setup (DONE) ==\n" )
 # Enable testing with BUILD_TESTING
 option(BUILD_TESTING "Build the testing tree." OFF)
 include(CTest)
+if(BUILD_TESTING AND NOT POLICY CMP0064)
+  message(FATAL_ERROR "CGAL support of CTest requires CMake version 3.4 or later.
+The variable BUILD_TESTING must be set of OFF.")
+endif()
 
 # and finally start actual build
 add_subdirectory( Installation )
diff --git a/Installation/CMakeLists.txt b/Installation/CMakeLists.txt
index 3d262b07bf5..89e4a61c5f3 100644
--- a/Installation/CMakeLists.txt
+++ b/Installation/CMakeLists.txt
@@ -135,7 +135,10 @@ else ( CGAL_BRANCH_BUILD )
   # Enable testing with BUILD_TESTING
   option(BUILD_TESTING "Build the testing tree." OFF)
   include(CTest)
-
+  if(BUILD_TESTING AND NOT POLICY CMP0064)
+    message(FATAL_ERROR "CGAL support of CTest requires CMake version 3.4 or later.
+The variable BUILD_TESTING must be set of OFF.")
+  endif()
 endif (CGAL_BRANCH_BUILD )
 
 #message(STATUS "Packages found: ${CGAL_CONFIGURED_PACKAGES}")