Adding unit test and refactoring

Added unit test for errormanager and refactored to simplify use of error_check() method.

tests/util/CMakeLists.txt

@@ -0,0 +1,18 @@
+
+
+cmake_minimum_required(VERSION 3.12)
+
+enable_testing()
+
+set (Boost_USE_STATIC_LIBS OFF)
+find_package(Boost COMPONENTS unit_test_framework)
+include_directories (${Boost_INCLUDE_DIRS} ../../src/)
+
+set (test_source
+./test_errormanager.cpp
+../../src/util/errormanager.c
+)
+
+add_executable(test_errormanager ${test_source})
+
+target_link_libraries(test_errormanager ${Boost_LIBRARIES})