Include CTest for BUILD_TESTING option

Allows skipping tests with -DBUILD_TESTING=OFF

CMakeLists.txt

@@ -379,11 +379,13 @@ set(DART_IN_SOURCE_BUILD TRUE)
 if(TARGET dart)
 
   # Add a "tests" target to build unit tests.
-  enable_testing()
-  if(MSVC)
-    add_subdirectory(tests)
-  else()
-    add_subdirectory(tests EXCLUDE_FROM_ALL)
+  include(CTest)
+  if (BUILD_TESTING)
+    if(MSVC)
+      add_subdirectory(tests)
+    else()
+      add_subdirectory(tests EXCLUDE_FROM_ALL)
+    endif()
   endif()
 
   # Add example subdirectories and an "examples" target.
@@ -431,7 +433,10 @@ endif()
 add_subdirectory(python)
 
 # Add 'ALL' target that builds everything
-set(all_target_candidates tests_and_run dartpy pytest)
+set(all_target_candidates dartpy)
+if (BUILD_TESTING)
+  set(all_target_candidates tests_and_run pytest)
+endif()
 foreach(target_candidate ${all_target_candidates})
   if(TARGET ${target_candidate})
     list(APPEND all_targets ${target_candidate})
@@ -687,7 +692,9 @@ endif()
 #===============================================================================
 message(STATUS "")
 message(STATUS "Run 'make' to build all the components")
-message(STATUS "Run 'make tests' to build all the tests")
+if (BUILD_TESTING)
+  message(STATUS "Run 'make tests' to build all the tests")
+endif()
 message(STATUS "Run 'make examples' to build all the examples")
 message(STATUS "Run 'make tutorials' to build all the tutorials")
 message(STATUS "Run 'make view_docs' to see the API documentation")