1. A method of controlling execution of transactions in a computing environment, said method comprising: initiating a transaction in a computing environment, the transaction effectively delaying committing transactional stores to main memory until completion of a selected transaction; and determining, by a processor, whether the transaction is to be aborted, the determining employing one or more controls of a control register used by the processor, the one or more controls to indicate whether transactions are to be randomly selected to be aborted for testing purposes, and wherein the control register comprises: a transaction diagnostic control, wherein a first value of the transaction diagnostic control indicates transactions are not to be aborted based on the transaction diagnostic control, a second value of the transaction diagnostic control indicates each transaction is to be aborted based on the transaction diagnostic control, and a third value of the transaction diagnostic control indicates transactions are to be randomly selected to be aborted; and a transaction diagnostic scope to indicate whether the transaction diagnostic control is to be applied, wherein a first value of the transaction diagnostic scope indicates the transaction diagnostic control is to be applied based on the processor being in a problem state or a supervisor state, and a second value of the transaction diagnostic scope indicates the transaction diagnostic control is to be applied exclusive to the processor being in the problem state.