Is it a must to do all kinds of testing for a system?

Question

There are different types of testing types.
For an example :
Functional testing types

• Smoke testing
• Regression testing etc...

Non functional testing types

• Performance testing
• Security testing
• Stress testing
• Usability testing etc...

I have given several major testing types. My question is, is it a must to do all these testing type for a system? I know each type has different purpose. But if I consider non functional testing, do I have to perform all types of testing? If not how to decide what types should be done?

Answer 1

That depends on what level of what the quality degree you want to reach, what resources you have and what the initial conditions are.

If you have the first draft version of the app then I does not make sense to perform Regression testing since Regression term is undefined for that build.

If your app is a middle-ware service then probably Usability testing will not make sense as well.

If your application is kind of atomic like calculator then Integration testing would probably not make sense.

So basically you have to perform the test types that make sense in terms of the changes you test, the environment your application works in, your commitments and the consequences which the possible defects can cause.

Answer 2

If not how to decide what types should be done?

Ask the stakeholders. If they don't know, then you'll have to go through it them in detail, talking about how the application will be used. Is it an internal tool or external? Is being performant important or not? Is it a disaster for the business if the product ships with issues, or is it acceptable for now? Is there sensitive data worth protecting as best as possible, or not?

Finally, what's the budget in both time and money for testing?

If you can get a discussion going on these points, then it will become clear the level of testing required, and what's possible.