Add target for building all tests

This allows to build all tests at once without
adding them to "all" target. In contrast to the
check target, the tests are not executed.

cmake/modules/TestTarget.cmake

@@ -56,7 +56,7 @@ if(CPP_UNIT_LIB OR META_NO_CPP_UNIT)
         set(META_PRIVATE_SHARED_LIB_COMPILE_DEFINITIONS ${META_PRIVATE_COMPILE_DEFINITIONS} ${META_ADDITIONAL_PRIVATE_SHARED_COMPILE_DEFINITIONS})
     endif()
 
-    # add target for test executable, but exclude it from the "all target" when EXCLUDE_TESTS_FROM_ALL is set
+    # add target for test executable, but exclude it from the "all" target when EXCLUDE_TESTS_FROM_ALL is set
     if(EXCLUDE_TESTS_FROM_ALL)
         set(TESTS_EXCLUSION EXCLUDE_FROM_ALL)
     else()
@@ -64,6 +64,13 @@ if(CPP_UNIT_LIB OR META_NO_CPP_UNIT)
     endif()
     add_executable(${TARGET_PREFIX}${META_PROJECT_NAME}${TARGET_SUFFIX}_tests ${TESTS_EXCLUSION} ${TEST_HEADER_FILES} ${TEST_SRC_FILES})
 
+    # add top-level target to build all test targets conveniently, also when excluded from "all" target
+    if(NOT TARGET tests)
+        add_custom_target(tests DEPENDS ${TARGET_PREFIX}${META_PROJECT_NAME}${TARGET_SUFFIX}_tests)
+    else()
+        add_dependencies(tests ${TARGET_PREFIX}${META_PROJECT_NAME}${TARGET_SUFFIX}_tests)
+    endif()
+
     # handle testing a library (which is default project type)
     if(NOT META_PROJECT_TYPE OR "${META_PROJECT_TYPE}" STREQUAL "library")
         # when testing a library, the test application always needs to link against it