Test Case Generation. X-Checker generates test cases that
exercise the programming API used by Windows Phone developers.
As illustrated in Section III, each test case is a sequence
of method calls to this API. The arguments to these calls are
either values with primitive data types, or references to objects
constructed and modified by method calls appearing earlier in
the sequence. The main challenge is to generate meaningful
method sequences that are also effective, i.e., the test case
generator should be able to elicit error cases in Xamarin
without generating too many test cases.