Updated test case for cast lints.
Updated test case for cast lints.

Also improved readability and reworded the messages.

graydon/rust,aidancully/rust,graydon/rust,graydon/rust,graydon/rust,aidancully/rust,graydon/rust,aidancully/rust,aidancully/rust,aidancully/rust,graydon/rust,aidancully/rust