refactor the spec
refactor the spec

* no instance variable; use around() instead
* uses context()
* use should() instead of expect()
* matchs full messages

taiki45/chanko,cookpad/chanko,taiki45/chanko,cookpad/chanko,damoguyan8844/chanko,damoguyan8844/chanko,damoguyan8844/chanko,taiki45/chanko,cookpad/chanko