fails:Hash#to_proc returns an instance of Proc
fails:Hash#to_proc the returned proc with a stored key returns the paired value
fails:Hash#to_proc the returned proc with no stored key returns nil
fails:Hash#to_proc the returned proc with no stored key when the hash has a default value returns the default value
fails:Hash#to_proc the returned proc with no stored key when the hash has a default proc returns an evaluated value from the default proc
fails:Hash#to_proc the returned proc raises an ArgumentError when calling #call on the Proc with no arguments
