Software Testing, QA

Equivalence class

Equivalence Classes is the input (and sometimes output) data which are processed by the same application or their processing leads to the same results.
Equivalence Class Testing is a technique for test design which can reduce the amount of your test cases.
It can be used at all testing levels – unit, integration, system, and system-integration test levels.

To ensure the correct program behavior under different input data, you should ideally test all possible values for each element of this data (as well all possible combinations of input parameters).

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Comments on: "Equivalence class testing" (8)

  1. Anonymous said:

    I like that answer about Equivalence Class Testing, it is really means, but I would like to also know about BVA.

  2. The best testing is smart testing! This equivalence class analysis affords the best bang for your buck.

    9 is a subset of 7 as stated. 7 should be revised to = 0, because both test cases need to be executed.

    Also, some testing needs to be done to ensure that all values in a particular equivalence class actually provide the same result. Hence classes 1-5 would all require what I assume BVA refers to in addition to random sampling within the sets. Yes, it is unnecessary to try every value from each class, but enough sampling should be done to give a reasonable expectation that All values are handled correctly.

    Some of the classes 6-11 are infinite sets. These require special handling.

    Non-alphanumeric character handling, and a very large input string are 2 additional classes.

    • Svetlana Kislaya said:

      Thanks for you addition)
      But more about BVA we’ll talk next time! 🙂

  3. vamshi said:

    Thank you very much for the information.its really gud

  4. Anonymous said:

    Svetlana, I’m completely agree with Dave. Tester can use classes of equivalence if he has 100% of sure in the style of code.
    We can compare two types of the same functionality:

    if ((!Int.TryParse(Age.Text.Trim(), out data) || data 100) || (textBox1.Text == “”))
    { MessageBox.Show(“Value is out of range”, “Warning”, MessageBoxButtons.OK, MessageBoxIcon.Error);

    and another one:

    if ((!Int.TryParse(textBox1.Text.Trim(), out data) || data 100
    {MessageBox.Show(“Value is out of range”, “Warning”, MessageBoxButtons.OK); return;}

    In the first case tester can use approach based on classes of equivalence, but the second example shows the failure of this approach.

    Classes of equivalence are very crafty. And we should be very carefully with their usage. Tester should know the style of programming to understand where he can use such approach.

    • Natalya Bosatskaya said:

      As I know, Equivalence Class Testing belongs to Black Box techniques, but this strategy is based solely on the requirements and specifications. See “A Practitioner’s Guide to Software Test Design” by Lee Copeland.

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