lower names -> shorter names

[MihaiCernat]

metoer-tuts chapter3 -> services -> conventions

Please favor longer names for small scope, lower names for large scopes. -> Please favor longer names for small scope, "shorter" names for large scopes.

metoer-tuts chapter3 -> services -> Dependency Injection

For example, we want to test that PaymentService.charge is been called ... -> For example, we want to test that PaymentService.charge is "being" called