Intersting Facts on Beautifull Testing chapter 2

In this chapter, it is shown the profound beauty of testing rather than it's superficial beauty.

The stake holders(interested parties) of testing are the people who are needed be satisfied. They are of two types.

1. Internal stake holders - doing, leading and managing test work
2. External stake holders - other interested parties

Examples for some of the stake holders can be mentioned as follows;

Fellow testers, test leads and managers, developers, development leads and managers, database and system architect, marketing and business analysts, project managers, tech support and help desk staff, vendors, customers,users etc.

Stake holders can be divided in some other groups depending on their attitude and contribution towards a project. Namely;

1. Nutral Stake holders - like legal bodies
2. Anti Stakeholders - like enemies who wish the unsuccessfulness of the project

Each stakeholder has a set of objectives and expectations  to be satisfied through testing. They need them to be efficiently, effectively and elegantly be carried out.

• Effectiveness - Satisfy the objectives.
• Efficiency - Satisfy the objectives and expectations in away that it maximizes the value.
• Elegance - Achieving efficiency and effectiveness gracefully and nicely.

For some clients the testers measure their effectiveness through the severity of the bugs they find.

External Beauty

DDP (Deffect Detection Percentage) = Bugs Detected/ Bugs Present

DDP (DDP before UAT) = Bugs Detected/ Test Bugs + Production Bugs


A test team’s DDP for a system test or system integration test averages around 85%. But if it is for internal use then DDP should be around 95%. If it is a safety/mission critical application then the DDP should be higher.

In testing, cost of quality refers to the recognized technique for measuring the cost of failures.

Cost of Detection - The testing costs on us even we couldn't find bugs.
Cost of Internal Failure - Testing and development costs such as filing bug reports, fixing bugs as a result of finding bugs.
Cost of External Failure - This includes support, testing and development costs that we have to bear because of a faulty system.

Average Cost of a Test Bug = Cost of Detection + Cost of Internal Failure/ test bugs

Average Cost of Production Bug = Cost of External Failure/Production bugs

Test ROI = (ACPB-ACTB) *test bugs/cost of detection