Ruby-Aware Code Completion

It is important to set up the code completion behavior in the Code Completion settings (File | Settings - Editor - Code completion on Windows/Linux, RubyMine | Preferences | Editor | Code completion on Mac).

Completing class name

If you want CamelHumps in code completion to be detected without using the Shift key, make sure that in the Code Completion page, the option Case sensitive is set to None.

Type inference