Unit 2 Boundary Value Testing, Equivalence Class Testing, Decision Table-Based Testing. ST 8 th Sem, A Div Prof. Mouna M.

Transcription

1 Unit 2 Boundary Value Testing, Equivalence Class Testing, Decision Table-Based Testing ST 8 th Sem, A Div Prof. Mouna M. Naravani

2 Dept. of CSE, BLDEACET, Vijarapur 2

3 Boundary Value Testing Boundary Value Analysis (BVA) Robustness Testing Worst case Testing Special Value Testing Random Testing Examples Dept. of CSE, BLDEACET, Vijarapur 3

4 Boundary Value Analysis (BVA) Boundary Value Analysis focuses on the boundary of the input space to identify test cases. The rationale behind value testing is that errors tend to occur near the extreme values of an input variable. Ex: Loop conditions may test for < when they should test for Dept. of CSE, BLDEACET, Vijarapur 4

5 BVA uses input variable values at their: Minimum (min) Just above the minimum (min+) A nominal value (nom) Just below their maximum (max-) Maximum (max) Dept. of CSE, BLDEACET, Vijarapur 5

6 Single Fault Assumption Dept. of CSE, BLDEACET, Vijarapur 6

7 a x1 b c x1 d Dept. of CSE, BLDEACET, Vijarapur 7

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10 Generalizing Boundary Value Analysis BVA can be generalized in 2 ways: By the number of variables (easy) By the kind of ranges (quite difficult) Dept. of CSE, BLDEACET, Vijarapur 10

11 Generalizing by the number of variables: If there are functions with n variables, hold all but one at the nominal value and let the remaining variables assume min, min+, nom, max-, max values, repeating this for each variable. Thus, for a function of n variables, BVA yields 4n + 1 unique test cases Dept. of CSE, BLDEACET, Vijarapur 11

12 Generalizing by the kinds of range: Depends on the nature/ type of variables themselves. When no explicit bounds are specified, as in Triangle problems, we usually have to create artificial bounds. The lower bound of side of lengths is 1, but what might be the upper bound? One possibility is, largest representable integer (MAXINT) Or impose an arbitrary upper limit such as 200 or BVA does not make much sense for Boolean variables: because the extreme values are TRUE or FALSE, and there is no clear choice for the remaining values Dept. of CSE, BLDEACET, Vijarapur 12

13 Limitations of Boundary Value Analysis Boundary Value Analysis works well when the program to be tested is a function of several independent variables that represent bounded physical quantities Dept. of CSE, BLDEACET, Vijarapur 13

14 Triangle Problem Boundary Value Analysis Test Cases Dept. of CSE, BLDEACET, Vijarapur 14

15 Commission Problem Boundary Value Analysis Test Cases Dept. of CSE, BLDEACET, Vijarapur 15

16 Robustness Testing Extension of Boundary value analysis. In addition to 5 BVA values of a variable, Robustness testing checks what happens when the extrema are exceeded with a value slightly greater than the maximum (max+) and a value slightly less than the minimum (min-). Generalizations and limitations of BVA applies directly to robustness testing Dept. of CSE, BLDEACET, Vijarapur 16

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18 The most interesting part of robustness testing is not with the inputs, but with the expected outputs. What happens when a physical quantity exceeds its maximum? Ex: if a variable is defined to be within a certain range, values outside that range result in run time errors that abort normal execution. Exception handling choice mandates robustness testing. Robustness testing generates 6n + 1 test cases Dept. of CSE, BLDEACET, Vijarapur 18

19 Worst-Case Testing Here, single value fault of Boundary value analysis is rejected. Worst case testing is interested in What happens when more than one variable has an extreme value. Start with the five-elements set that contains min, min+, nom, max-, max. Then take the cartesian product of these sets to generate test cases. Boundary value analysis test cases are a proper subset of worst-case test cases. Worst-case testing is more thorough form of testing. Also requires more effort. Worst-case testing for a function on n variables generates 5 n test cases Dept. of CSE, BLDEACET, Vijarapur 19

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21 Robust Worst-case testing This involves the cartesian product of the seven-element sets used in robustness testing. Robust Worst-case testing for a function on n variables generates 7 n test cases Dept. of CSE, BLDEACET, Vijarapur 21

22 Triangle Problem Worst-case test cases Dept. of CSE, BLDEACET, Vijarapur 22

23 Triangle Problem Worst-case test cases contd Dept. of CSE, BLDEACET, Vijarapur 23

24 NextDate Worst-case test cases Dept. of CSE, BLDEACET, Vijarapur 24

25 Special Value Testing Special Value testing occurs when a tester uses domain knowledge, experience with similar programs and information about soft spots to device test cases. No guidelines are used other than to use best engineering judgement. Special value testing is very dependent on the abilities of the tester Dept. of CSE, BLDEACET, Vijarapur 25

26 Random Testing Rather than always choosing min, min+, nom, max-, max values of a bounded variable, use a random number generator to pick test case values. Ex: derived from Visual Basic application, where a x b x = Int((b a + 1) * Rnd + a) Where, function Int returns integer part of floating point number, the function Rnd generates random numbers in the interval [0, 1]. Question: How many random test cases are sufficient? Dept. of CSE, BLDEACET, Vijarapur 26

27 In each of the following table, the program went through seven cycles that ended with the hard-to-generate test case. avg./percentage: last line shows what percentage of the random test cases was generated for each column Dept. of CSE, BLDEACET, Vijarapur 27

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30 References Paul C. Jorgensen: Software Testing, A Craftsman s Approach, 3 rd Edition, Auerbach Publications, Dept. of CSE, BLDEACET, Vijarapur 30

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