So, when automation finds bugs, your cycle time increases. When people claim cycle time reduction, they "overlook" this fact. why? Those bugs will be found by manual testing too. This may or may not be the case. Bugs discovered by human testing and Automation tend to be of different types.
Now, let us track that trail of what happens a bug is discovered -
In automation - situation could be bit tricky especially when the automation tests, logs are bigger. An error/bug reported by an automation bug needs to be checked to see if it is a bug in automation code or a bug in application or bug in data setup or some timing or synchronization related problem (in GUI automation scenario). Let us say you have 5-7 pages of log file - you will have to scan/read through the log file an locate the bug. You might have to do execute failed automated test manually (and corresponding data setup etc).
In manual testing, human tester can easily trace and follow the bug trail and document the bug. At a high level, bug investigation and isolation tasks tend to become relatively low.
Hence, when automation discovers a bug - things get really problematic.
If one were to cut down cycle time by automation or otherwise, they HAVE to make sure either "no bugs are discovered" or "any discovered bugs are IGNORED" or "bugs that are discovered, if fixed, not tested again and other regression testing is done ....
Can automation control or influence any of above events - prevents bugs being discovered or igonore the bugs if accidently discovered or mandate that bugs fixes will not be subsequently tested?
For the sake of argument, let us suppose that both human test cycle and Automation find same number of bugs ... and take out "bugs" portion of test cycle, how automation can save test cycle time? On what parameters this cycle time reduction by Automation depends ?
Type of test - nature of interactions between "test execution agent" (human or an automated script) and nature of verifications (during and post execution).
- GUI Forms with lots of data input fields - can result in quick form fill tests when automated (zero think time).
- Tests that require longer processing time can not gain from automation as automation can not speed up the processing time.
- Tests that require visual inspection - window titles, error messages, color, tool tip and other GUI centric elements - are better tested manunally as programmatic tests would mean lots of investment. Human testes are quicker and cheaper in such cases.
- Result verification that requires detailed analysis, text file processing, database check etc are good candidates for gaining cycle time.