tests FEATURE include tests into build system

basic tests of ly_set implementation
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 0202a3a..6827dc0 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -21,19 +21,19 @@
     set(CMAKE_BUILD_TYPE debug)
 endif()
 
-set(CMAKE_C_FLAGS         "${CMAKE_C_FLAGS} -Wall -Wextra -std=c89")
+set(CMAKE_C_FLAGS         "${CMAKE_C_FLAGS} -Wall -Wextra -std=c99")
 set(CMAKE_C_FLAGS_RELEASE "-O2 -DNDEBUG")
 set(CMAKE_C_FLAGS_PACKAGE "-g -O2 -DNDEBUG")
 set(CMAKE_C_FLAGS_DEBUG   "-g -O0")
 
 # options
-#if((CMAKE_BUILD_TYPE STREQUAL debug) OR (CMAKE_BUILD_TYPE STREQUAL Package))
-#    option(ENABLE_BUILD_TESTS "Build tests" ON)
-#    option(ENABLE_VALGRIND_TESTS "Build tests with valgrind" ON)
-#else()
-#    option(ENABLE_BUILD_TESTS "Build tests" OFF)
-#    option(ENABLE_VALGRIND_TESTS "Build tests with valgrind" OFF)
-#endif()
+if((CMAKE_BUILD_TYPE STREQUAL debug) OR (CMAKE_BUILD_TYPE STREQUAL Package))
+    option(ENABLE_BUILD_TESTS "Build tests" ON)
+    option(ENABLE_VALGRIND_TESTS "Build tests with valgrind" ON)
+else()
+    option(ENABLE_BUILD_TESTS "Build tests" OFF)
+    option(ENABLE_VALGRIND_TESTS "Build tests with valgrind" OFF)
+endif()
 #option(ENABLE_CALLGRIND_TESTS "Build performance tests to be run with callgrind" OFF)
 
 #option(ENABLE_CACHE "Enable data caching for schemas and hash tables for data (time-efficient at the cost of increased space-complexity)" ON)
@@ -270,12 +270,12 @@
 # YANG extensions plugins
 #set(EXTENSIONS_LIST "nacm" "metadata" "yangdata")
 # if the tests are enabled, build libyang_ext_test
-#if(ENABLE_BUILD_TESTS)
-#    find_package(CMocka 1.0.0)
+if(ENABLE_BUILD_TESTS)
+    find_package(CMocka 1.0.0)
 #    if(CMOCKA_FOUND AND CMAKE_BUILD_TYPE MATCHES debug)
 #        list(APPEND EXTENSIONS_LIST "libyang_ext_test")
 #    endif(CMOCKA_FOUND AND CMAKE_BUILD_TYPE MATCHES debug)
-#endif(ENABLE_BUILD_TESTS)
+endif(ENABLE_BUILD_TESTS)
 
 #if(ENABLE_STATIC)
 #    set(EXTENSIONS_LIST_SIZE " 0 ")
@@ -327,19 +327,19 @@
 # yang2yin
 #add_executable(yang2yin ${yang2yinsrc})
 
-#if(ENABLE_VALGRIND_TESTS)
-#    set(ENABLE_BUILD_TESTS ON)
-#endif()
+if(ENABLE_VALGRIND_TESTS)
+    set(ENABLE_BUILD_TESTS ON)
+endif()
 
-#if(ENABLE_BUILD_TESTS)
-#    if(CMOCKA_FOUND)
-#        enable_testing()
-#        add_subdirectory(tests)
-#    else(CMOCKA_FOUND)
-#        message(STATUS "Disabling tests because of missing CMocka")
-#        set(ENABLE_BUILD_TESTS NO)
-#    endif(CMOCKA_FOUND)
-#endif(ENABLE_BUILD_TESTS)
+if(ENABLE_BUILD_TESTS)
+    if(CMOCKA_FOUND)
+        enable_testing()
+        add_subdirectory(tests)
+    else(CMOCKA_FOUND)
+        message(STATUS "Disabling tests because of missing CMocka")
+        set(ENABLE_BUILD_TESTS NO)
+    endif(CMOCKA_FOUND)
+endif(ENABLE_BUILD_TESTS)
 
 #if(GEN_LANGUAGE_BINDINGS AND GEN_CPP_BINDINGS)
 #    add_subdirectory(swig)