The belonging of two data elements to the same equivalence class simply means that the function performs the same operations on each of them. The belonging of two data elements to different equivalence classes means that there is at least one line of the code required to process one data element that will not be used while processing another data element. Often, data belonging to one of the two equivalence classes are called valid data, and data of the second equivalence class are invalid data for the given function. The branches of the code that are used to process the valid data are called successful branches, while the branches that the function performs when processing the invalid data are called unsuccessful branches. The design documentation defines the valid and invalid input for most functions.

To choose test cases for each equivalence data class, testers must read the project documentation. If this information is not available, the tester will have to perform the functional testing and recover the equivalence classes in a bottom-up manner. In some cases, the design documentation can also use valid and invalid data for this function. Testing of the functionality with invalid data is fairly accurately called negative testing. Invalid data are used to ensure that each function has exception handler to deal with invalid data situations. Negative testing is not limited to just running test scenarios only with invalid data.

Why are the services of load testing companies in demand? The reason for such popularity is ability of their providers to optimize performance of IT products.

For example, one of the principal distinctive features of a test technician using rapid test technology is that when estimating the actual probability of hidden errors that may interfere with the effectiveness of the end product, he always takes into account the breadth and extent of testing. To ensure testing of both successful and unsuccessful branches within each function, the tester must pay close attention to equivalence classes.

The equivalence class is a set of tests with similar parameters, and after testing one of them, you can tick the box that says all the others have been also tested (the rest of the parameters will have the same result).

Equivalent tests are tests that produce the same result.

Specifically if we perform two any tests from one equivalence class, we get the same result.