TL;DR

The first software testing technique that every software tester heard off is regression testing. But what is the regression testing oracle? The post is aligned with the Black Box Software Testing Foundations course (BBST) designed by Rebecca Fiedler, Cem Kaner, and James Bach.

In regression testing, we compare results from the previous build with results from the current build. The result from previous build is the oracle. In an automated test suite, oracles are encoded in a number of asserts. In skilfull testing, asserts are encoded in your experience, knowledge or testing notes.

Advantages of regression testing are that verification is straightforward compare, automated regression can generate and verify large amounts of data and we have a large number of tools that support regression testing.

Disadvantages are false alarms. Application features changed and assert do not hold anymore. There is also the possibility of bug miss. The bug could also be missed in the previous build or could be present in new features for which we do not have asserts.

Tactic for regression testing is simple and straightforward. It is very easy to explain how do you actually test. It is important, but be aware that this is not only available testing approach.