Week 9

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A “W4” Category University

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Lecture 25

CHAPTER 4

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Specification-Based OR Black-Box OR I/O Testing Techniques

It view the software as a black box with inputs and outputs, but they have no knowledge of how the system or component is structured inside the box.

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Equivalence Partitioning (EP)

is to divide the input data of a software into partition of

data from which test cases can be derived.

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Equivalence Partitioning:

1. In this method the input domain data is divided into different equivalence data classes.

2. This method is typically used to reduce the total number of

test cases.

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EXAMPLE 1

If you are testing for an input box accepting numbers

from 1 to 1000 then there is no use in writing thousand

test cases for all 1000 valid input numbers plus other

test cases for invalid data.

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1. One input data class with all valid inputs. Pick a single value from range 1 to 1000 as a valid test case. If you select other values between 1 and 1000 then result is going to be same. So one test case for valid input data should be sufficient.

2. Input data class with all values below lower limit. I.e. any value below 1, as a invalid input data test case.

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EXAMPLE 2

The valid range for the month is 1 to 12, representing January to December. This valid range is called a partition. In this example there are two further partitions of invalid ranges. The first invalid partition would be <= 0 and the second invalid partition would be >= 13.

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1. An input has certain ranges which are valid and other ranges which are invalid.

2. Only one test case of each partition is needed to evaluate the behaviour of the program

3. Use more or even all test cases of a partition will not find new faults in the program.

4. If one condition in the partition work we assume all of the conditions in that partition will work.

5. The number of test cases can be reduced considerably.

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Example 3

Consider a form field which ask for the age of a person. let the age should be >=18 and <=50.

SOLUTION

==>> values less than 18(invalid class) ==>> values between 18-50 (valid class) ==>> value greater than 50 (invalid class)

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CLASS WORK 1

The following input conditions will be tested:

1. For the first three digits of all social security

numbers, the minimum number is 111 and the

maximum number is 222.

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SOLUTION

The first three digits of the social security number are:

1. >= 111 and < =222 (valid input),

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The fourth and fifth digits of the social insurance (security) number are:

5. >= 11 and <= 99, (valid input)

6. < 11 (invalid input, below the range)

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CLASSWORK 2

What will be the equivalence partitions if:

1. A balance in the range $0 up to $100

2. A balance over $100 and less than $1000 3. A balance of $1000 and over.

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Invalid

partition (3% interest)Valid (5% interest)Valid (7% interest)Valid

-$0.01 $0.00 $100.00 $100.01 $999.99 $>=1000.00

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Class Work 3

How to apply Equivalence Partitions if:

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SOLUTION

Divide the students under the same intervals for same

group according to there age

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Purpose of Equivalence Partitioning

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Boundary Value (BV)

“An input value or output value which is on the edge of

equivalence partition e.g. the minimum and maximum

value of a range.”

Boundary Value Analysis (BVA)

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1. It’s widely recognized that input values at the extreme

ends of input domain cause more errors in system.

2. More application

errors occur at the boundaries of

input domain. ‘Boundary value analysis’ testing

technique is used to identify errors at boundaries

rather than finding those exist in center of input

domain.

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Test cases for input box accepting numbers between 1

and 1000 using Boundary value analysis:

1. Test cases with test data exactly as the input

boundaries of input domain i.e. values 1 and 1000 in

our case.

2. Test data with values just below the extreme edges of

input domains i.e. values 0 and 999.

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Boundary Value Analysis PROCEDURE

There is an interval from 0 to 10 then in the BVA attempt 6 step procedure:

1) Check for the (min-1) 0-1=-1 2) Check for the (min) 0

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Boundary Value Analysis (Range Checking)

“An input value or output value which is on the edge of

equivalence partition e.g. the minimum and maximum

value of a range.”

Example1

Consider a printer that has an input option of the

number of copies to be made, from 1 to 99

invalid valid invalid

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invalid valid invalid

0 1 99 100

In boundary value analysis , we will take the min and max (boundary) values from the valid partition (1 and 99 in this case), together with first and last value in each of invalid partitions (0 and 100 in this case)

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Invalid

-$0.01 $0.00 $100.00 $100.01 $999.99 $1000.00

Class Work 1

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How to calculate the max value for 7% interest?

Invalid

-$0.01 $0.00 $100.00 $100.01 $999.99 $1000.00

1- Go back to the specification to see if a max has been stated somewhere for the balance amount.

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CLASSWORK 2

Equivalence partition and boundary value analysis

Telephone system for a company with 200 telephones has 3 digit extension numbers from 100 to 699.

We can identify the following partitions and boundaries

-_{Digits (0 to 9): valid partition(s) ___________ invalid partition(s) ______} -_{Number of digits: invalid boundary values ______ and ________}

-_{Range of extension numbers :}

valid _____ and ______ ,invalid boundary value _____ and ___

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EXAMPLE

Consider a component, generate_grading, with the following specification:

The component is passed an exam mark (out of 75) and a coursework (c/w) mark (out of 25), from which it generates a grade for the course in the range 'A' to 'D'. The grade is calculated from the overall mark which is calculated as the sum of the exam and c/w marks, as follows:

greater than or equal to 70 - 'A'

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The partitions for the two inputs are initially identified.

The

valid partitions

can be described by:

0 <= exam mark <= 75

0 <= coursework mark <= 25

The most obvious

invalid partitions

based on the inputs

can be described by:

exam mark > 75

exam mark < 0

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CLASS EXERCISE

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• _{Why use decision table} • _{Decision table definition} • _Applications

• _{Steps to create a decision}

table

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Why Use Decision Tables?

Equivalence partitioning and boundary value analysis applied to specific inputs.

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HOW?

1. One of the fields on a form contains a text box which accepts numeric values in the range of 18 to 25. Identify the invalid Equivalence class.

2. In an Examination a candidate has to score minimum of 24 marks in order to clear the exam. The maximum that he can score is 40 marks. Identify the Valid Equivalence values if the student clears the exam.

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Why Use Decision Tables?

1. Equivalence partitioning and boundary value analysis applied to specific inputs.

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Definition

“A table showing combinations of inputs (causes/conditions) with

their associated outputs (effects/expected

results/actions/outcomes ), which can be used to design test cases.”

Causes Values 1 2 3 4 5 6 7 8

Cause 1 Y, N Y Y Y Y N N N N

Cause 2 Y, N Y Y N N Y Y N N

Cause 3 Y, N Y N Y N Y N Y N

Effects

Effect 1 X X X

Effect 2 X X X

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Decision Table Testing

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1. List all causes in the decision table

2. Calculate the number of possible combinations

3. Fill columns with all possible combinations

4. Check covered combinations 5. Add effects to the table

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Step 1: List all causes

Causes Values 1 2 3 4 5 6 7 8 Cause 1 Y, N Y Y Y Y N N N N Cause 2 Y, N Y Y N N Y Y N N Cause 3 Y, N Y N Y N Y N Y N

Effects

Effect 1 X X X

Effect 2 X X X

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Step 2: Calculate Combinations

• _{If all causes are simply Y/N}

OR T/F values:

Causes Values 1 2 3 4 5 6 7 8

Cause 1 Y, N Y Y Y Y N N N N

Cause 2 Y, N Y Y N N Y Y N N

Cause 3 Y, N Y N Y N Y N Y N

Effects

Effect 1 X X X

Effect 2 X X X

Combinations

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Step 3: Fill Columns

Conditions 1 2 3 4 5 6 7 8

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Step 4: Check Covered Combinations

• _Checksum

• _{For each column calculate the}

combinations it represents

Causes Values 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

Customer Type A,B,C,O A A A A B B B B C C C C O O O O

2 or more lines Y, N Y Y N N Y Y N N Y Y N N Y Y N N

Credit rating = X Y, N Y N Y N Y N Y N Y N Y N Y N Y N

Effects

Normal Letter X X X X X X X X ? ? ? ?

Special Letter X X X X ? ? ? ?

Add. Paragraph ? X X ? X X ? X X ? ? ? ?

No Letter ? ? ? ?

Checksum 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 16

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Conditions 1 2 3 4 1. Deductible met? Y Y N N 2. Type of visit D H D H Actions

1. Reimburse 50% X

Step 5: Add effects to table

• _{Read column by column}

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Example Decision Table

Loan application, where you can enter the amount of monthly repayment OR the number of years to take to pay it back.

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Step 2: Calculate the Combinations

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Step 5: Add Effects to Columns

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Change Outcome

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