One of the problems in software testing is to specify and verify the execution of a sequence of method calls in object-oriented software. In this paper, we introduce JMSeq to propose a formal method based on context-free grammars to specify a sequence of method calls; it provides a simple way to verify and monitor the program under test. JMSeq uses no code instrumentation as in AspectJ and verication is done at runtime. JMSeq shows that runtime verication through code annotations with no instrumentation can be a new approach in software testing that is simple and expressive enough.