cmocka free operation and catching exceptions

I started my adventure with cmocka library, and I have two questions.

Is it possible to find out if free() operation was made correctly? I mean, I would like to test function which is cleaning up tree structure. I've read about test_free(), but honestly I don't understand idea behind that.

The second thing is case of catching standard library exceptions. I know about function expect_assert_failure, but how to use it? For example I would to do something what will throw segmentation fault, but I would like to pass test anyway.