The word test is used as a noun and as a verb.

We need a definition of test that is context-neutral and the most suitable definition comes from the American Heritage Dictionary.

Test: (noun) a procedure for critical evaluation; a means of determining the presence, quality, or truth of something; a trial

This statement seems to capture the essence of what is meant by a test – but there are three variations. Well this isn’t so bad I think, as all three taken together give us the foundations we need. Let’s take a closer look at each one.

A procedure for critical evaluation

Critical evaluation involves a skilful judgement as to the truth or merit of something. A test is a procedure, usually with a series of steps that include some form of preparation, execution, results gathering, analysis and interpretation. This isn’t a definitive description of a test procedure. There could be more steps and one could break these main steps down further.

The procedure doesn’t necessarily require prepared documentation, but many tests are so documented. The important thing is that there is a perspicacious thought process at the heart of a test.

This thought process is driven by the need to evaluate the system under test with respect to its adequacy, consistency, behaviour, accuracy, reliability or any other significant aspect or property.

A means of determining the presence, quality, or truth of something

A test could determine the presence (or absence) of something easily enough, but quality is a different matter: the term is loaded with emotional connotations, but we are rescued by the dictionary.

A quality can be, “an essential or distinctive characteristic, property, or attribute”. Now we can see that a test can reveal these properties.
Can a test determine the truth of something? Well this makes good sense too. Typically, we need to test an assertion such as, “this system meets some requirement ” or “this system behaves in such a way” or “this system is acceptable” and so on.

There’s a certain amount of subjective judgement involved but we can see that a test or tests could provide evidence for someone to exercise that judgement and make a decision.

A trial

The notion of a trial implies that the process of testing a system will help us to evaluate that system with respect to its qualities. The purpose of such an evaluation is normally to make a decision.

The decision might be to accept or reject the system, but it might also be to expose its shortcomings so they can be remedied in some way. A test might also influence an individual or organisation to change direction – to rethink a design; to relax or change a requirement; to scrap a component and start again; to buy rather than build or build rather than buy.

A natural way of looking at a system under test is that it is on trial, and will be judged in some way.

The definition of testing

From our definition of the noun test, we can derive a verb easily enough.

Test: (verb) to critically evaluate; to determine the presence, quality, or truth of something; to conduct a trial.