QA, QC & Testing

Testing Types

Testing can be divided into two areas:

 • black box testing

 • white box testing

Black box testing works on the principle that the internal workings of the product under test are not known to the person carrying out the testing.

All the tester needs to know in a Black box test scenario, is what to put in (input) and what is expected at the other end (output). What happens in between is no concern to the black box tester.

If the product under test is an alarm clock. Then the black box testing methodology assumes that the internal workings of the alarm clock are not needed to be known.

The programming used to keep the time synchronised, the electronics used in the circuit board and so on, play no relevance to the black box testing.

Black box testing is putting something in and expecting something out without understanding what happens in between.

White Box Testing

White box testing is the opposite whereby the person carrying out the testing knows the internal workings of the product under test. What happens between the input and output of a test needs to be understood and analysed by the white box tester.

Consider, Formula 1 motor racing, the test driver's remit is to see whether the car can perform as it should do. As a consequence, the test driver doesn't need to understand or know the internal workings of the car's engine.

The Formula 1 test engineers on the other hand, who monitor the engines performance need to know how the engine works in order to interpret the test data that their monitoring equipment produces whilst the test driver is testing the car.

The test driver is carrying out black box testing whilst the test engineers are carrying out white box testing.

White box testing requires an understanding of how the internals of the product work.

White box testing is beyond the scope of this course as it requires substantial knowledge of the internal workings of the product under test. Instead this course will concentrate on Black box testing.

Black Box Testing

In the world of Black box testing, there are generally two areas into which this form of testing can be divided,

 • Non-functional testing

 • Functional testing

Non-functional testing is where the product behaviour is assessed, whilst Functional testing is where a product is assessed on how it works.

Consider a 4x4 also known as a Sports Utility Vehicle (SUV). Functionally testing the vehicle would look at seeing how it works. Whether the 4x4 system, steering and so on work as they should.

Non Functional testing would look at how the vehicle behaves such as when it is taken off road. Does it behave as a typical off road vehicle or does it behave like a normal car, in that it gets stuck in the mud and can't climb steep hills.

Both sets of tests are important in proving that the vehicle meets the required standards.

Summary

 • Black box testing is putting something in and expecting something out without understanding what happens in between.

 • White box testing is putting something in and expecting something out whilst understanding what happens in between.

 • Functional testing involves assessing whether the product works as expected.

 • Non-functional testing involves assessing whether the product behaves as expected.