Equivalence partinioning and boundary value analysis
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The document discusses different techniques for designing effective test cases, namely equivalence partitioning and boundary value analysis. It states that these are considered the best black box testing techniques. Equivalence partitioning involves dividing the input domain into equivalence classes and selecting one representative value from each class. Boundary value analysis focuses on testing values at the boundaries or extremes of the input domain, as errors often occur near these boundaries. Using both techniques together can help ensure an error-free product by comprehensively testing the input space.
Equivalence partinioning and boundary value analysis
- 1. SUBMITTED TO:- MR.MOHIT SINGH CSE DEPARTMENT SUBMITTED BY:- NIHARIKA 2011BTCS006
- 2. The practice of testing software has become one of the most important aspects of the process of software creation. When we are testing software the first and potentially most crucial step is to design test cases. MANY TEST CASES BEST TEST CASE
- 3. • BOUNDARY VALUE ANALYSIS and EQUIVALENCE PARTIONIONING are known as the best test cases. • These are the type of black box testing • It is very important to do both the tests together to ensure an error free product.
- 4. EQUIVALENCE PARTIONING • In this method the input domain data is divided into different equivalence data classes. This method is typically used to reduce the total number of test cases to a finite set of testable test cases, still covering maximum requirements. • In short it is the process of taking all possible test cases and placing them into classes. One test value is picked from each class while testing.
- 5. CLASS A CLASS B CLASS C 1- 100 100-200 200-300 • Suppose the input domain for a function is 1 to 300. • It is impossible to create 300 test cases . • So we divide the input variables into classes. • Then we select one value from each class. • This one value will represent whole of the class
- 6. Now all of the input domain have been categorized in their respective classes and one variable has been chosen from each class. BUT, it is a well known fact that error tend to occur near the extremities of the input variable. So, here comes the need for :- BOUNDARY VALUE ANALYSIS
- 7. • Boundary value analysis focuses on the boundary of the input space to identify test cases. • The rationale behind boundary value analysis is that errors tend to occur near the extreme values of an input variable. • Programs written in non-strongly typed languages are more appropriate candidates for boundary value testing such as FORTRAN,COBOL. 7 BOUNDARY VALUE ANALYSIS
- 8. • Lets define two variables ,X1 and X2. Where X1 lies between A and B and X2 lies between C and D. • A ≤ X1 ≤ B • C ≤ X2 ≤ D • The values of A, B, C and D are the extremities of the input domain. These are best demonstrated by the figure.
- 9. The yellow shaded area is the input domain.
- 10. The values used to test the extremities are:- • Min ------------------------------------ - Minimal • Min+ -----------------------Just above Minimal • Nom ------------------------------------ - Average • Max- ---------------------Just below Maximum • Max ---------------------------------- Maximum
- 11. The green dots represent the boundary values.
- 12. Few examples to demonstrate the need for boundary value analysis. • Programmer forgets to use <= instead use <. • Programmer forgets to use count 0 while using counter variable. • Next date problem. • Triangle problem. BVA is very useful in cases of future prediction of the test results of any product.
- 13. • The NextDate problem is a function of three variables: day, month and year. Upon the input of a certain date it returns the date of the day after that of the input. • The input variables have the obvious conditions: • 1 ≤ Day ≤ 31. • 1 ≤ month ≤ 12. • 1812 ≤ Year ≤ 2012.
- 14. BVA is based on CRITICAL FAULT ASSUMPTION • The Critical Fault Assumption also known as the single fault assumption in reliability theory. The assumption relies on the statistic that failures are only rarely the product of two or more simultaneous faults. Upon using this assumption we can reduce the required calculations dramatically. • The function f that computes the number of test cases for a given number of variables n can be shown as: f = 4n + 1 • As there are four extreme values this accounts for the 4n. The addition of the constant one constitutes for the instance where all variables assume their nominal value.
- 15. LIMITATIONS OF BVA • Boundary value analysis works well when the program to be tested is a function of several independent variables that represent bounded physical quantities. • Boundary value analysis selected test data with no consideration of the function of the program, nor of the semantic meaning of the variables. • We can distinguish between physical and logical type of variables as well (e.g. temperature, pressure speed, or PIN numbers, telephone numbers etc.)
- 16. Hence, together boundary value analysis and equivalence partitioning result in the best black box test case. The test case values can be represented as:- Class A Class B a bm The domain a to b is divided into two classes. Class A and B. Boundary values are found in both the classes.