As the use of mobile devices becomes increasingly ubiquitous, the need for systematically testing applications (apps) that run on these devices grows more and more. However, testing mobile apps is particularly expensive and tedious, often requiring substantial manual effort. While researchers have made much progress in automated testing of mobile apps during recent years, a key problem that remains largely untracked is the classic oracle problem, i.e., to determine the correctness of test executions. This paper presents a novel approach to automatically generate test cases, that include test oracles, for mobile apps. The foundation for our approach is a comprehensive study that we conducted of real defects in mobile apps. Our key insight, from this study, is that there is a class of features that we term user-interaction features, which is implicated in a significant fraction of bugs and for which oracles can be constructed - in an application agnostic manner -- based on our common understanding of how apps behave. We present an extensible framework that supports such domain specific, yet application agnostic, test oracles, and allows generation of test sequences that leverage these oracles. Our tool embodies our approach for generating test cases that include oracles. Experimental results using 6 Android apps show the effectiveness of our tool in finding potentially serious bugs, while generating compact test suites for user-interaction features.