In this post we explain why definition of Grey Box Software Testing approach given by Black Box Software Testing Foundations course (BBST) created by Rebecca Fiedler, Cem Kaner and James Bach is definition that is applicable in Agile project.
At daily standup meeting, developer mentioned that testers should probably use grey box approach in order to test new feature. As a new and talented tester, you do not have a clue what is grey box software testing.
There is no standard definition of grey box software testing approach. We will use examples in order to depict this approach in your mind.
In grey box software testing approach, you still try to answer question:
Does this do what the users (human and software) expect?
But in order to answer this question, you are using internal product information that is contained in product code or internal data.
For example, you are testing airplane ticketing shop where first time visitors get discount of 10%. Users are expecting a discount, and you know the amount of this discount. Also, users from different countries, get different additional discount, so you are designing tests based on internal data (two discount values), and with user expectation that they will receive a discount.
Grey box testing is asking same question as black box testing, Does this do what the users (human and software) expect? But here your testing approach is using information that is contained in source code or internal data.