CMake/Ninja: give 'features' target direct terminal access

This will cause the output to be displayed while cucumber executes our
features instead of when it's finished. Additionally, because it has
direct terminal access, we can rely on cucumber's auto detection to
enable color instead.

Author: muggenhor

CMakeLists.txt

@@ -200,9 +200,16 @@ else()
         set(CUKE_COMPILE_DYNAMIC_CPP_STEPS '"${CMAKE_COMMAND}" --build "${CMAKE_BINARY_DIR}" --target e2e-steps')
 
         function(add_feature_target TARGET_NAME)
+            # Ensure we get colored output from cucumber and give it direct terminal access if
+            # possible. Direct terminal access would cause the output to be displayed as it's being
+            # produced instead of when cucumber is finished.
             if(CMAKE_GENERATOR STREQUAL "Ninja")
                 list(APPEND ARGN --color)
             endif()
+            set(USES_TERMINAL)
+            if(NOT CMAKE_VERSION VERSION_LESS 3.2)
+                set(USES_TERMINAL USES_TERMINAL)
+            endif()
             add_custom_target(${TARGET_NAME}
                 COMMAND ${CUCUMBER_RUBY}
                 TEST_FEATURES_DIR=${CUKE_TEST_FEATURES_DIR}
@@ -215,6 +222,7 @@ else()
                 ${ARGN}
                 ${CUKE_FEATURES_DIR}
                 DEPENDS cucumber-cpp
+                ${USES_TERMINAL}
                 )
         endfunction(add_feature_target)