They say that it is the early bird that catches the worm. The same is true in software testing.The process starts with a requirement and from this point onwards, there is gradually more and more effort being applied to the creation or modification of an application. More people become involved and the cost of the solution increases. This is the natural course of events. It is therefore a natural conclusion, that if a mistake is made in the requirement, the cheapest time to fix the problem, is as the requirement is being defined, or immediately afterwards. This keeps the cost to a minimum. The same logic applies to design, development and test. Yes, even testing has the ability to insert defects, with badly written scenarios, scripts or reporting defects that are not real.
Defects are introduced throughout the software development lifecycle and the art of testing is to find as many of them as possible when they are inserted. It is widely recognised that there is a parabolic curve of defect insertion. The starting point is the requirement specification which begins by inserting 60% of the defects. The curve terminates with live or production, where the intended result is to find 0 defects. The tester should report on completion of the project, the defect detection efficiency. This looks at understanding for each defect, where it was inserted and where it was detected. A perfect test process would look to identify each defect as it is inserted. This is highly unlikely and the reality is that some defects will be found in later phases of testing, or indeed in live.
It is important to understand that projects testing budgets can double when critical steps such as static testing are not performed. This forces 60% of the defects into later phases, incurring as a minimum the cost of the design. Projects also often suffer from slippages and with test execution occurring at the end of the process, is often squeezed or compromised. The project must also realise that reducing the testing duration or coverage, is likely to increase the risk of a defect being found in live, where in comparison to it being found and removed in the requirements phase, will cost 10,000 times more to resolve, at best 10 times more. The reality here is that a defect undetected until live, can be business impacting, brand damaging and could cause a business to fail.
Defects are introduced throughout the software development lifecycle and the art of testing is to find as many of them as possible when they are inserted. It is widely recognised that there is a parabolic curve of defect insertion. The starting point is the requirement specification which begins by inserting 60% of the defects. The curve terminates with live or production, where the intended result is to find 0 defects. The tester should report on completion of the project, the defect detection efficiency. This looks at understanding for each defect, where it was inserted and where it was detected. A perfect test process would look to identify each defect as it is inserted. This is highly unlikely and the reality is that some defects will be found in later phases of testing, or indeed in live.
It is important to understand that projects testing budgets can double when critical steps such as static testing are not performed. This forces 60% of the defects into later phases, incurring as a minimum the cost of the design. Projects also often suffer from slippages and with test execution occurring at the end of the process, is often squeezed or compromised. The project must also realise that reducing the testing duration or coverage, is likely to increase the risk of a defect being found in live, where in comparison to it being found and removed in the requirements phase, will cost 10,000 times more to resolve, at best 10 times more. The reality here is that a defect undetected until live, can be business impacting, brand damaging and could cause a business to fail.
It is therefore important that testing is involved in the project from the outset, not as something that is included if there is the time, the budget and the inclination. Only by the application of systematic testing throughout the project is the quality level going to be understood and the opportunity to remedy problems in a timely manner presented.
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