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A few basic rules worth following while bug hunting

Software Testing

A few basic rules worth following while bug hunting

Every tester, apart from their own intuition and experience, has a number of helpful books at their disposal, which contain some valuable guidance regarding testing. However, for most members of the testing community, number one go-to book is the ISTQB Syllabus, which has proved invaluable when it comes to preparing for the ISTQB exam (International Software Testing Qualifications Board)

Listed below are 7 basic testing rules included in the ISTQB Syllabus, which provide basic tips applicable in all types of testing. Their implementation in the project’s life cycle improves work of the whole development team.

1. Testing reveals bugs, but it cannot prove there aren’t any

The fact that we didn’t find any errors in the app, doesn’t mean we should celebrate just yet. There’s still possibility that not all errors have been revealed. Testing increases chance of finding any unwanted errors, however, even if tester reports 100 bugs there can always be a 101st.

2. Thorough testing is impossible

Apart from small and simple systems, we can’t assume that the app was tested thoroughly. Calculator test is a great example, running all of it’s combinations would be very time-consuming and costly at the same time, compared to the potential benefit of performing such test. This rule shows the importance of risk assessment, prioritisation and right choice of testing technology.

3. Early testing saves time and money

If an app is in it’s late stage of development, it will be quite expensive to find and fix it’s errors. It costs significantly less to make necessary corrections already on the documentation testing stage. Involvement of the testing team early on saves time and money

4. Defect clustering

According to the sylabus, usually most of the defects discovered during testing have their source in small number of modules. As a result, predicted defect clusters are an essential part of risk assessment, which allows to concentrate effort more efficiently during testing.

5. Paradox of the pesticides

It’s a very interesting rule, which compares constant use of the same pesticides (pests develop immunity to the specific pesticide) for testing the same thing the same way. It’s very beneficial to modify tests and testing data to increase chances of detecting malfunctions. However, it’s worth mentioning, as per the syllabus, that in certain cases – such as automated regression testing – paradox of the pesticides might be profitable, because it allows to make sure the number of regression-related defects is insignificant.

6. Testing depends on context

As it is in everyday life, context matters. For example, testing a food ordering system, we take a drastically different approach, than testing software for a space shuttle. The level of complexity and cruciality of a respective application has an impact on the path we take during testing. As the syllabus suggests, another example can be different manners of testing for agile project menagement and for V-model software development.

7. Assumption that there are no errors is an error in itself

This rule reconfirms the first and second rule and also specifies that if we are convinced about the app’s full reliability and that all the bugs have been revealed and fixed, it doesn’t mean that it is completely error-free. The app might still work below the user’s expectations and be difficult to operate.

There is more than one side to testing, this way it’s more interesting. There are many rules, patterns and good practice to follow when testing, but at the same time, there’s still space for creativity and listening to one’s own instincts.

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