Summer is a Java-based test development and test execution framework similar to JUnit and TestNG, but supporting model based testing techniques (like NModel for C#). Tests in Summer like in the frameworks mentioned are presented as test classes and test methods. One of test class'es methods is marked as returning the current test state, so a test class is interpreted as state machine description. The corresponding test is automatically constructed during execution (usign so called online test generation) as a sequence of test method calls, in which each test method is executed at least once in each state reached. In addition to test construction based on state mechine models Summer supports specification of functionality under test in pre- and postconditions, similar to CodeContracts framework.