Revert "chore: Remove moc_included_test.cpp"

This reverts commit 2ec66c8.

CMakeLists.txt

@@ -1094,6 +1094,7 @@ add_library(mixxx-lib STATIC EXCLUDE_FROM_ALL
   src/util/logger.cpp
   src/util/logging.cpp
   src/util/mac.cpp
+  src/util/moc_included_test.cpp
   src/util/movinginterquartilemean.cpp
   src/util/performancetimer.cpp
   src/util/rangelist.cpp
@@ -2092,6 +2093,7 @@ add_executable(mixxx-test
   src/test/wbatterytest.cpp
   src/test/wpushbutton_test.cpp
   src/test/wwidgetstack_test.cpp
+  src/util/moc_included_test.cpp
 )
 find_package(GTest CONFIG REQUIRED)
 set_target_properties(mixxx-test PROPERTIES AUTOMOC ON)

src/util/moc_included_test.cpp

@@ -0,0 +1,8 @@
+#include "../mocs_compilation.cpp"
+
+// QT_VERSION will be defined by any moc_<header_base>.cpp file included from mocs_compilation.cpp
+// It is empty in case all moc files are included, a requirement to speed up incremental builds.
+// See https://cmake.org/cmake/help/latest/prop_tgt/AUTOMOC.html for details.
+#ifdef QT_VERSION
+#error mocs_compilation.cpp not empty. Move all #include "moc_<header_base>.cpp" lines from mocs_compilation.cpp to the cpp files of the related classes.
+#endif