A professional tester approaches a product with the mind-set that the product is already broken – it has bugs and it is their job to find out them. They suppose the application under test is inherently defective and it is their job to ‘illuminate’ the defects.

This methodology/approach is required in testing.

Designers and developers approach software with an optimism based on the guess/assumption that the changes they make are the accurate solution to a particular problem. But they are just that – assumptions.
Without being proved they are no more correct than guesses. Developers often neglect primary ambiguities in specification documents in order to complete the project; or they fail to identify them when they see them. Those ambiguities are then built into the code and represent a bug when compared to the end-user’s needs.
By taking a skeptical approach, the tester offers a balance.

A Good Professional tester:

• Takes nothing at face value.
• Always asks the question “why?”
• Seek to drive out certainty where there is none.
• Seek to illuminate the darker part of the projects with the light of inquiry.

Sometimes this attitude can bring argument with Development Team. But development team can be testers too! If they can accept and adopt this state of mind for a certain portion of the project, they can offer excellent quality in the project and reduce cost of the project.
Identifying the need for Testing Mindset is the first step towards a successful test approach and strategy.

Must Read – Testing ISN’T About Learning. It is About Thinking.