cmake: simplify tests handling

Move the requirement checking and the dummy test where they are used.
Use REQUIRED instead of the manual FOUND check and error handling.

Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>

CMakeLists.txt

@@ -313,17 +313,7 @@ list(APPEND EXTRA_LIBS "m")
 add_subdirectory(src)
 add_subdirectory(doc)
 
-if(ENABLE_TESTS)
-  find_package(CppUTest)
-  if(CPPUTEST_FOUND)
-    enable_testing()
-  else()
-    message(SEND_ERROR "CppUTest not found")
-  endif()
-else()
-  enable_testing()
-  add_test(NAME notests COMMAND true)
-endif()
+enable_testing()
 add_subdirectory(tests)
 
 configure_file(config.h.cmake config.h @ONLY)

tests/CMakeLists.txt

@@ -25,4 +25,6 @@ endif()
 
 if(ENABLE_TESTS)
   add_subdirectory(unit)
+else()
+  add_test(NAME notests COMMAND true)
 endif()

tests/unit/CMakeLists.txt

@@ -22,6 +22,8 @@
 enable_language(CXX)
 
 remove_definitions(-DHAVE_CONFIG_H)
+
+find_package(CppUTest REQUIRED)
 include_directories(
   ${CPPUTEST_INCLUDE_DIRS}
   ${PROJECT_BINARY_DIR}