We have discussed the importance of Automation Testing and also why it is not substitute for Manual Testing. Now, lets throw more light on the scenarios where introducing Automation as part of the Test Plan can not be a good idea.
Frequently changing requirements :
Creating automated scripts for the application where requirements are updated or changed on frequent basis can be extremely challenging, as with each update in existing functionality you will have to update the Test cases & of-course you don’t want to end up updating Test scripts every time . You need to understand behavior of the requirements coming from client side. If the requirements are coming through proper channel and finalized then it is safe to involve automation testing.
Unstable UI :
Same goes with the UI as well. Let’s say you are not getting much changes in the functional requirement but your UI gets updated frequently. It can vary from few fields to entire look and feel restructure. In any case you have to update your automated scripts and sometimes entirely restructure of the scripts is required for large UI changes.
Functional Complexity :
Sometimes functionalities are extremely complex where test automation can be a major challenge expecting more time and cost investment. In case of subjective validation, functions must be verified by Humans to make sure usability and Look-feel is as per the requirement. Manual testing is the best option for that.
Less repetitive execution :
Even if we are including Automation, we need to prioritize those test cases that are to be automated by giving them weightage on risk, ease for automation and most importantly frequency of execution. Some scenarios are meant to be executed very few times during the whole testing life-cycle. Better to avoid such scenarios in automation to maintain high productivity.
Lack of skill-full resources & Budget Constraints :
At last even if your each criteria meets to go ahead with Automation testing but there are no such resources available with proper skill-set and your project is having budget crunch to hire new resources than it is advisable to stick to Manual Testing only.