What is Test Oracle in Manual Testing?

Question

One Interviewer asked this question to me in an interview in Agilsys. I googled about this. but I didn't find a clear cut explanation from online. Can you please tell me what it is?

Answer 1

An oracle is a means by which we recognize a problem when we encounter one in testing.

https://www.developsense.com/blog/2015/09/oracles-from-the-inside-out/

(Not in "manual" testing. https://www.developsense.com/blog/2013/02/manual-and-automated-testing/; https://www.developsense.com/blog/2017/11/the-end-of-manual-testing/)