Compiler does help with a lot of things that you'd require unit tests for with a dynamic language.
Example:
Runtime wouldn't be able to give you a protocol between how two classes would communicate. Say your service object that handles authentication. You would have to write unit tests so the two classes involved would know how to respond to each other.
Example: Runtime wouldn't be able to give you a protocol between how two classes would communicate. Say your service object that handles authentication. You would have to write unit tests so the two classes involved would know how to respond to each other.