Test tool logic and testing methods are provided for facilitating testing a duplexed computer function, such as a duplexed coupling facility. The test tool allows a testcase written for a first environment to be automatically driven in a second environment, thereby facilitating testing of a function of the second environment. Other aspects include logic for intercepting a system event by a test tool to facilitate testing of system-managed event processing, and for adjusting a display characteristic of one or more messages to be displayed by the test tool based on message type. Further, logic for propagating an environmental error indication and for facilitating processing a wait state are also provided, as are several new test tool verbs and macros.