The most of developers test and write test cases but not many of them use the special test design techniques. Step by step, gaining experience, they realize that continuously make the job which includes the same rules. Later they find out that all these rules have already been described by someone else.
We want to present you a brief description of the most common test design techniques:
- Equivalence Partitioning – EP. For example, you need to select one correct value a range of values within the range of 1 to 10 say 5, and one incorrect value outside the interval say 0.
- Boundary Value Analysis – BVA. If we take the example above, as the values for a positive test we choose the minimum and maximum limits (1 and 10) and the values greater than and less than limits (0 and 11). Boundary value analysis can be applied to records, files, fields or any related entities that have limitations.
- Cause/Effect – CE. This is usually the entering combinations of test conditions (a cause) for getting an answer from the system (an effect). For example, you check the ability to add the client using the define screen form. To do it you have to enter some fields, such as “Name”, “Address”, “Phone Number” and then click “Add” – this is a “cause.” After clicking “Add”, the system adds the client to the database and displays it on the screen –this is an “effect.”
- Error Guessing – EG. This is when a test analyst uses his knowledge of the system and ability to interpret specifications subject to “guess” with what kind of input conditions the system can fail. For example, the specification says “The user must enter the code.” The test analyst thinks, “What if I won’t enter the code?” or “What if I enter the wrong code?” and so on. This is the error guessing.
- Exhaustive Testing – ET. This is an extreme case. According to this technique, you need to check all possible combinations of entering values and it should find all the defects. In practice, this method is not possible, due to the huge amount of entering values.