Software testing is the process of evaluating a software product to identify any defects or errors. It is an essential part of the software development life cycle (SDLC) and helps to ensure that the software meets its requirements and is of high quality.
There are seven key principles of software testing that should be followed in order to achieve the best results. These principles are:
1. Testing shows the presence of defects, not their absence:
This principle states that it is impossible to prove that a software product is defect-free. Testing can only show that defects are present, not that they are not present. This is because there are an infinite number of possible inputs and scenarios that could be tested.
Example:
Imagine you are testing a new social media application. You test the application with a variety of valid inputs and scenarios, and you find no defects. However, this does not mean that the application is defect-free. It is possible that there are still defects in the application that were not triggered by your tests.
2. Exhaustive testing is impossible:
Exhaustive testing is the process of testing all possible inputs and scenarios for a software product. As mentioned above, this is impossible to do because there are an infinite number of possible inputs and scenarios.
Example:
Imagine you are testing a new e-commerce application. The application allows users to browse and purchase products from a variety of categories. There are an infinite number of possible product combinations that a user could add to their cart. It would be impossible to test all of these combinations.
3. Early testing saves time and money:
The earlier defects are found in a software product, the easier and cheaper they are to fix. This is because the defects have not yet been propagated to other parts of the system.
Example:
Imagine you are developing a new software product and you do not start testing until the product is almost complete. You find a major defect in the product that requires a significant amount of work to fix. This will delay the release of the product and increase the cost of development.
4. Defects cluster together:
Defects tend to cluster together in certain areas of a software product. This is because defects are often caused by the same underlying problem.
Example:
Imagine you are testing a new software product and you find a defect in the login module. You decide to test other parts of the login module to see if there are any other defects. You find several other defects in the login module, which suggests that there is a deeper problem with the module’s design or implementation.
5. Beware of the pesticide paradox:
The pesticide paradox states that if you use the same test cases over and over again, you will eventually stop finding new defects. This is because the defects that can be found with those test cases have already been found.
Example:
Imagine you are testing a new software product and you use the same test cases every week. After a few weeks, you stop finding new defects. This suggests that you need to develop new test cases that can find the remaining defects in the product.
6. Testing is context dependent:
The type and amount of testing that is required for a software product depends on the context in which the product will be used. For example, a safety-critical product, such as a medical device, will require more rigorous testing than a non-safety-critical product, such as a game.
Example:
Imagine you are testing a new medical device. The device is used to monitor patients’ vital signs. It is important that the device is accurate and reliable. Therefore, you will need to perform rigorous testing to ensure that the device meets its requirements.
7. Beware of the absence-of-errors fallacy:
The absence-of-errors fallacy states that if a software product has been tested and no defects have been found, then the product is defect-free. This is a fallacy because, as mentioned above, it is impossible to test all possible inputs and scenarios for a software product.
Example:
Imagine you have tested a new software product and you have not found any defects. You release the product to production and you find a major defect that causes the product to crash. This suggests that there is a problem with your testing process.