Assert (Combined Fragment)   An assertion interaction operator (signified by the value of assert) defines a combined fragment where the messages contained in the fragment are the only valid messages that can occur in the context. If any other messages occur they are considered to be invalid.

Explanation

The assertion operator is used when the modeler needs to specifically define the messages that are valid. Any other messages other than those defined in the assertion are considered to be invalid and should not occur. The assertion states that unless the messages defined in the assertion occur the interaction is considered to be invalid. It is a useful operator in terms of defining test cases. This concept occurs in everyday life when only a single event can occur in a particular context. For example queuing at a delicatessen where you must take a number-sequenced ticket and wait for your number to be called before being served.

Related Entries

Consider (Combined Fragment)  Graphically Similar A combined fragment with an operator of negative (neg) is related to a combined fragment with an operator of assertion (assert) because if the set of traces defined by the assertion operator do not occur exactly in the sequence indicated the entire set of messages are considered to be invalid.

Consider (Combined Fragment)  Graphically Similar A combined fragment with an operator of consider is related to a combined fragment with an operator of assertion (assert) because they are often used together, where an assertion is nested inside a consider fragment.

Ignore (Combined Fragment)  Graphically Similar A combined fragment with an operator of ignore is related to a combined fragment with an operator of assertion (assert) because they are often used together, where an assertion is nested inside an ignore fragment.