Question

SW Acquisition and Project Management

Comment on the statement "Cannot test 100% of everything". What is crucial to test?

Answer 1

The answer to the above problem is as follows-

The statement "Cannot test 100% of everything" implies the following-

This statement means that it is impossible to test a product/software/machine or anything in a complete manner or by 100%. Testing can only be done to reduce the number of undiscovered defects and it is impossible to discover all the defects. It is just that we can reduce the number of defects that are known to us through testing.

Complete testing, also known as exhaustive testing is done so that after the testing phase is over, there are no known problems exsisting in the system.

This complete or 100% testing cannot be done because-

• The domain of all possible input, all possible combinations of inputs and its pre-conditions are simply too large to be completely incorporated in the testing phase. And here we have to look at both valid as well as invalid input combinations. Due to many time constraints on the inputs, the program may behave differently at different states. A valid input may not be valid at all times and vice-versa is true for invalid ones too.
• Then there are a number of design issues that crop up due to complexities in designing the system. Implicit decision making and assumptions lead to these desing issues.
• Also, all the possible outside factors cannot be taken into account while developing a system. If a system is vulnerable to outside influences like weather, season, pressure, height etc, then its impossible to test this type of system to 100% perfection.

So these factors are very crucial to testing phase and owing to these reasons, it is correct to state that 100% testing cannot be done.

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