1. A method for testing an event processing system, comprising: declaring input data, output data, and a processing rule for a test in a test file, wherein the test file is associated with a test schema that is designed for testing the event processing system; associating each input event of a stream of input events with a time stamp; associating each of one or more expected output events with a shared timestamp; sending the stream of input events to an event processing system; applying a sliding window on the stream of input events that are sent to the event processing system; processing, with said event processing system, the stream of input events in a batch mode with one or more sliding cycles, wherein said sliding window includes one or more input events from the stream of input events in a sliding cycle that corresponds to the one or more expected output events; receiving one or more actual output events at an end of said sliding cycle in the batch mode from the event processing system, each of the one or more actual output events associated with a timestamp; and using said one or more expected output events to verify said one or more actual output events, including: verifying whether the timestamp associated with each said actual output event matches the shared timestamp associated with said one or more expected output events in the sliding window, and determining that an assert fails when at least one timestamp associated with said one or more actual output events does not match the shared timestamp associated with said one or more expected output events in the sliding window.