Support verbose output of the test suites

generate add ctest test-suites, with the --verbose argument to be given
to the test suites.
The verbose output will be shown **only** if ctest is run with `-v` parameter
The verbose argument is to the test-suites, only when run through `ctest`
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 96ce7f9..97dc3cf 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -31,7 +31,7 @@
     include_directories(${CMAKE_CURRENT_SOURCE_DIR})
     add_executable(test_suite_${data_name} test_suite_${data_name}.c)
     target_link_libraries(test_suite_${data_name} ${libs})
-    add_test(${data_name}-suite test_suite_${data_name})
+    add_test(${data_name}-suite test_suite_${data_name} --verbose)
 endfunction(add_test_suite)
 
 if(CMAKE_COMPILER_IS_GNUCC OR CMAKE_COMPILER_IS_CLANG)