In fact, it is impossible to check every possible sequence of program instructions. This has been proved by QA professionals providing independent verification and validation services.
During each session of the program, you can monitor the sequence of its operators’ performance from start to finish. The sequences may differ from one another by fragments of code or the procedure.
To illustrate the problem, let us turn to a very simplified example. Imagine a system that can reach only several states and there are only several transitions between them, but this system, nevertheless, is hard to test. The example is based on the errors detected during testing of an actual program.
The system starts at state 1. This is its ground state, and it returns to it at every given opportunity.
- From state 1, it always goes to state 2.
- From state 2, it can go to state 3 or 5.
- From state 3, it can go to state 4 or 5.
- From state 4, it can go to state 3, 5 or 6.
- From state 5, it can go to state 1, 4 or 6.
- From state 6, it can go to state 3 or 5.
Only six states – well, what can I test? But it is not as simple as it seems at first thought. In fact, the testing team found that, if the system, before getting to the state 6, thirty times go from the state 4 to the state 5, the operation will fail. What do you think, how many different run sequences should be tested in order to find this error if not to assume its existence in advance?
Professional services automation (PSA) software is used to track costs and times, schedule resources and manage projects from start to finish.
This bug has been found in the PBX phone system. In state 1 the phone is silent. When the phone rings (state 2), either the owner picks up the phone (state 3 – connection) or the caller hangs up (the state 5 – off). Answering the call, the owner of the phone can press the Hold button (state 4) and hang up (state 5). While the caller is on the phone (or till he hangs up), the owner can answer another call (state 6 – waiting in the waiting line switching). When the owner hangs up, stopping both current and pending calls, the phone will return to the state 1.
The phone line of PBX operator is often busy, and the operator very often uses the HOLD button that is the line retention button. When the operator presses the Hold button, the computer puts some information in the temporary storage area called the stack. When you return the pending call the computer deletes the information from the stack. When the operator hangs up the phone, and the phone returns to the passive state, the program erases entire stack in case one of the routines has forgotten to erase its data.
Penetration testing service is provided to fortify security infrastructure against cyber attacks.
Add Comment