Minor cmake code duplication improvement

Create a macro to add tests for both static/header only.

The only differneces between these two are the libraries they link
with and the target names. Created the simple macro:

_spdlog_prepare_test(<target> <spdlog_lib>)

which does the work.
Signed-off-by: Andrei-Florin BENCSIK <andrei.bencsik@gmail.com>

tests/CMakeLists.txt

@@ -38,31 +38,25 @@ endif()
 file(MAKE_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}/logs")
 enable_testing()
 
-# The compiled library tests
-if(SPDLOG_BUILD_TESTS)
-    add_executable(spdlog-utests ${SPDLOG_UTESTS_SOURCES})
-	spdlog_enable_warnings(spdlog-utests)
-    target_link_libraries(spdlog-utests PRIVATE spdlog)
-
+macro(_spdlog_prepare_test test_target spdlog_lib)
+    add_executable(${test_target} ${SPDLOG_UTESTS_SOURCES})
+	spdlog_enable_warnings(${test_target})
+    target_link_libraries(${test_target} PRIVATE ${spdlog_lib})
 	if(systemd_FOUND)
-		target_link_libraries(spdlog-utests PRIVATE ${systemd_LIBRARIES})
+		target_link_libraries(${test_target} PRIVATE ${systemd_LIBRARIES})
 	endif()
 	if(SPDLOG_SANITIZE_ADDRESS)
-		spdlog_enable_sanitizer(spdlog-utests)
+		spdlog_enable_sanitizer(${test_target})
 	endif()
-    add_test(NAME spdlog-utests COMMAND spdlog-utests)
+    add_test(NAME ${test_target} COMMAND ${test_target})   
+endmacro()
+
+# The compiled library tests
+if(SPDLOG_BUILD_TESTS)
+    _spdlog_prepare_test(spdlog-utests spdlog::spdlog)
 endif()
 
 # The header-only library version tests
 if(SPDLOG_BUILD_TESTS_HO)
-    add_executable(spdlog-utests-ho ${SPDLOG_UTESTS_SOURCES})
-	spdlog_enable_warnings(spdlog-utests-ho)
-    target_link_libraries(spdlog-utests-ho PRIVATE spdlog::spdlog_header_only)
-	if(systemd_FOUND)
-		target_link_libraries(spdlog-utests-ho PRIVATE ${systemd_LIBRARIES})
-	endif()
-	if(SPDLOG_SANITIZE_ADDRESS)
-		spdlog_set_address_sanitizer(spdlog-utests-ho)
-	endif()
-    add_test(NAME spdlog-utests-ho COMMAND spdlog-utests-ho)
+    _spdlog_prepare_test(spdlog-utests-ho spdlog::spdlog_header_only)
 endif()