CEN 5070 – Software V&V BOUNDARY TESTING © 2001-2008, Dr. E.L. Jones

CEN 5070 – Software V&V

BOUNDARY TESTING

© 2001-2008, Dr. E.L. Jones

2/2000 Unit Test Concepts 2

Agenda

• More on Boundary Points & Values

• Automated Test Data Generation

• Boundary Testing Approach

• Test Set Reduction Strategies


BOUNDARY TESTING DESIGN METHODOLOGY

• Specification

• Identify elementary boundary conditions

• Identify boundary points

• Generate boundary test cases

• Update test script (add boundary cases).


(1) Specification

• Compute pay for an hourly employee, given the number of hours worked and the hourly pay rate. Compute overtime at 1.5 times hourly rate for hours in excess of 40.

SoftwareunderTest

Hours Pay

Rate


(2) Identify Boundary Conditions

• Condition 1 (bc1): Hours <= 40

• Observations:• Condition taken directly from decision table


(3) Identify Boundary Points

• bc1 Boundary Points• Point 1: AT the boundary: Hours = 40

• Point 2: Just INside: Hours = 39

• Point 3: Just OUTside: Hours = 41

• Observations:• The Hours value must be paired with Rate

• Inclusive inequalities have 3 boundary points


(4) Generate Test Cases

• Combine Hours boundary points with Rate• Case 1 (AT): Hours = 40, Rate = 10, Pay=400

• Case 2 (IN): Hours = 39, Rate = 10, Pay=390

• Case 3: (OUT): Hours = 41, Rate=10, Pay=415

• Observations:• Test each boundary point individually

• Then consider pair-wise boundary points


(5) Update Test Script

StepStimuli Expected Response

Hours Rate Pay =

1

2

30

50 10

10 300

550

3 40 10 400

4 39 10 390

5 41 10 415


Your TurnBoundary Testing

c1: Age <= 12 | Y N N

c2: Age > 65 | Y N N

c3: Age > 80 | Y

c4: Weight > 300 | Y N N N N

c5: Weight > 120 | N Y

a1: Pills = 0 | X X

a2: Pills = 1 | X

a3: Pills = 2 | X X

a4: Pills = 2+(W-120)/50 | X

Decision Table:


Your Turn (2-3) Boundary Conditions/Points

Boundary Condition Boundary Point (BP)AT IN

bc1:

OUT

bc2:

bc3:

bc4:

bc5:


Your Turn(4) Generate Boundary Test Cases

• To create a test case, you must pair an Age with a Weight• Weight boundary point + NOMINAL Age

• Age boundary point + NOMINAL Weight

• OUT Age + OUT Weight A nominal value is one that is not close to a boundary point. For simplicity, use the same nominal value in all test cases.


Your Turn(4) Boundary-Nominal Test CasesCondition btc BC Weight Age Expect

Weight>300 1 IN 301 21 0

2 OUT 300 21

Age <= 12 3 IN 220 11

4 AT 12

5 OUT 13

Age > 65 6 IN

7 OUT

Age > 80 9 IN

10 OUT

Weight>120 11 IN

12 OUT


Your Turn(4) Out-Out Boundary Test Cases

Condition OUT BP

Weight Age btc Weight Age Expect

>300 <=12 13

>65 14

>80 15

>120 <=12 16

>65 17

>80 18


OBSERVATIONS

• Functional testing defines a minimal number of test cases

• Boundary testing adds a large number of test cases, but are EASY to create

• Boundary testing finds lots of errors!


BOUNDARIES EXIST FOR

• Optional fields: (present, missing).

• Variable length data: null string, max length

• Database tables: empty

• Searching: first/last position

• File: closed, empty


Agenda






Agenda






Tools for Boundary Testing

• Ref – MS thesis, Jermaine Stewart, 2006

• Versions: BTDgen.run, BTDgenGUI.run

• Unix invocation: % BTDgen

• BTDgen: specification Boundary Test Sets• Full cartesian product – high volume [btd_xxx.txt]

• Reduced set (nominal values) [bnc_xxx.txt]

• Specification: var declarations + boundary conditions.


Agenda






Boundary Test Set Reduction

• Cartesian product yields exponential size

• Boundary-nominal yields linear size• By-passes “masking” problem

• Multiple boundaries not tested

• Combinatorial methods applied to each variable’s boundary value set.


RANDOM TESTING

• Beyond scope of this lecture

• Used to bombard software with inputs (high volume testing)

• No effort to identify expected results

• Appropriate for automated load testing, where concern is for capacity/volume.


MAIN POINTSBLACK-BOX TESTING

• Black-box = spec-based testing• Tests intentions• Key knowledge = stimuli and responses• Decision table organizes S/R conditions• Boundary testing flushes coding errors• Black-box test case design can drive

software design -- same issues addressed


PUTTING IT ALL TOGETHER

• Test design is a systematic process • whether you use decision tables or not, you

must understand the factors influencing and influenced by the behavior of the unit

• The sooner you design test cases, the better• Test design is more crucial than running tests• Reveals assumptions, omissions and errors

• Use test cases during design and coding


SOLUTIONS TO EXERCISES


Your Turn(2) Identify Boundary Conditions

• Condition 1 (bc1): Age <= 12

• Condition 2 (bc2): Age > 65

• Condition 3 (bc3): Age > 80

• Condition 4 (bc4): Weight > 300

• Condition 5 (bc5): Weight > 120


Your Turn(3) Identify Boundary Points

Boundary Condition Boundary PointAT IN

bc1: Age <= 12

OUT

bc2: Age > 65

bc3: Age > 80

bc4: Weight > 300

bc5: Weight > 120

12 11

66

81

301

121

13

65

80

300

120


Your Turn(4) Boundary-Nominal Test Cases

Condition btc BC Weight Age Expect

Weight>300 1 IN 301 21 0

2 OUT 300 21 5

Weight>120 3 IN 121 21 2

4 OUT 120 21 2

Age <= 12 5 AT 220 12 1

6 IN 220 11 1

7 OUT 220 13 4

Age>65 8 IN 220 66 2

9 OUT 220 65 4

Age>80 10 IN 220 81 0

11 OUT 220 80 2


Your Turn(4) Out-Out Boundary Test Cases

Condition OUT B-point

Weight Age btc Weight Age Expect

>300 <=12 12 300 13 5

>65 13 300 65 5

>80 14 300 80 5

>120 <=12 15 120 13 2

>65 16 120 65 2

>80 17 120 80 2

Documents

CEN 5070 – Software V&V BOUNDARY TESTING © 2001-2008, Dr. E.L. Jones