Adhoc testing is an informal and unstructured software testing type that aims to break the testing process to find possible defects. It is performed without proper planning and documentation, and it does not follow any structured way of testing. Adhoc testing can be achieved with the software testing technique called Error Guessing, which can be done by people having enough experience on the system to "guess" the most likely source of errors. Adhoc testing can be an extension of existing documented test cases but intends to apply invented variations of those test cases improvisationally without formally documenting the specifics beforehand. Adhoc testing can be performed when there is limited time to do elaborative testing, and it is usually performed after the formal test execution.
Adhoc testing is useful for adding additional confidence to a resulting product or process, as well as quickly spotting important defects or inefficiencies. It can help create unique test cases and improve testing coverage by identifying defects that other approaches may miss. However, it has some disadvantages, such as having inherent uncertainties in its performance and not being as useful without proper documentation post-execution and completion. Defects found using this method are hard to replicate as there are no test cases aligned for those scenarios.
To get the most from an ad hoc test and limit its downsides, the test should be properly documented post-execution and completion, and the results report should address how any defects found will be addressed. Adhoc testing can be efficient and productive, but as skilled and experienced testers, we also need to determine when to forego this approach.
