Software Test Design Techniques

Software Test Design Techniques

1) Introduction to Software Test Design Techniques

2) Static and Dynamic Test Design Techniques

3) Black box Test Design Techniques

    a) Equivalence Partitioning (EP)

    b) Boundary Value Analysis (BVA)

    c) Decision Table Testing

    d) State Transition Testing

    e) Use Case Testing
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1) Introduction to Software Test Design Techniques
 

> What is Technique?

An Efficient way of doing or achieving something.

> What is Test Design Technique?

A test design technique is used to select a good set of tests from the all possible tests for a given system.

> Why we need to use Test Design Techniques?

Exhaustive Testing is not possible, so we need to use Test Design Techniques in order to reduce the size of the input.

Exhaustive Testing is a Test approach in which the test suite comprises all combination of input values and preconditions.

Exhaustive Testing is not recommendable due to Time and Budget considerations.

> Categories of Test Design Techniques?

There are two main categories of Test Design Techniques, They are:

    a) Static Techniques
    b) Dynamic Techniques
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2) Static and Dynamic Test Design Techniques


A) Static Techniques
 

> Testing of the software documents manually or with a set of tools but without executing the Software.

Two types of static testing techniques

i) Reviews (Manual Examination)

ii) Static Analysis (Automated Analysis)
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i) Reviews
 

Types of Reviews

a) Informal Review
b) Walkthrough
c) Technical Review
d) Inspection

ii) Static Analysis
 

Static analysis tools are typically used by developers, Compilers offer some support for Static analysis,
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B) Dynamic Test Design Techniques
 

> The software is tested by executing it on computer.

Categories of Dynamic Test Design Techniques

i) Specification based or Black box Techniques    a) Equivalence Partitioning (EP)
    b) Boundary Value Analysis (BVA)
    c) Decision Table Testing
    d) State Transition Testing
    e) Use Case Testing Etc...

ii) Structure based or White box Techniques    a) Statement Testing and coverage
    b) Decision Testing and Coverage
    c) Condition Testing, Multi Condition Testing etc...

iii) Experience based Techniques    a) Error Guessing
    b) Exploratory Testing
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3) Black box Test Design Techniques
    

    a) Equivalence Partitioning (EP)

    b) Boundary Value Analysis (BVA)

    c) Decision Table Testing

    d) State Transition Testing

    e) Use Case Testing
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a) Equivalence Partitioning (EP)
 

• It can be applied at any level of testing (Unit, Integration, System and Acceptance Testing)

• In Equivalence Partitioning, inputs to the Software are divided into groups that are expected to exhibit similar behavior.

• Equivalence Partitions/Classes can be found for both valid data and invalid data.

Example 1 (Data Range):

Tickets field in a Reservation system accepts 1 to 10 Tickets only.

Partition 1    Partition 2    Partition 3

0                 1 to 10         11 to 99 or above
(Invalid)       (Valid)          (Invalid)

Example 2 (Data Type):

Customer Identification Number field in a CRM system accepts only numbers.

Partition 1        Partition 2    Partition 3              Partition 4     
Alpha bytes      Numbers     Special Characters    Alpha-numeric 

(Invalid)          (Valid)         (Invalid)                  (Invalid)               

Example 3 (Data Size)

Phone Number filed accepts 10 digits number only

Partition 1    Partition 2    Partition 3
Below 10      10               Above 10
(Invalid)       (Valid)         (Invalid)

Example 4 (Others)

A Payment management system accepts credit card payments only

Partition 1     Partisan 2         Partisan 3
Credit card    Net Banking      Cash on Delivery
(Valid)          (Invalid)            (Invalid)
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b) Boundary Value Analysis (BVA)
 

• The maximum and minimum values of a partition are its boundary values.

• Behavior at edge of each equivalence partition is more likely to be incorrect than behavior within the partition.

• Boundary value analysis can be applied at all Test levels(Unit, Integration, System and Acceptance Testing).

Example 1:
Partition 1    Partition 2    Partition 3

0                  1 to 10        11 to 99 or above
(Invalid)        (Valid)        (Invalid)

Minimum/maximum 0
Minimum 1
Maximum 10
Minimum 11
Maximum 99
-------------------------------------
Example 3 (Data Size)

Phone Number filed accepts 10 digits number only

Partition 1    Partition 2    Partition 3
Below 10      10               Above 10
(Invalid)      (Valid)          (Invalid)

Minimum -9
Minimum and Maximum - 10
Maximum -11
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Example: User Id field accepts 10 to 20 characters

Partition 1    Partition 2    Partition 3
Below 10     10 to 20        11 to 99

Minimum -1
Maximum - 9

Minimum - 10
Maximum - 20

Minimum - 21
Maximum -99
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c) Decision Table Testing
 

• The decision tables are good way to capture system requirements that contain logical conditions.

• It may be applied for all situations when the action of the software depends on logical decisions.

BSRB (Govt) System Job eligibility criteria,

Age should be in between 21 and 35

Conditions:
i) For SC or ST Candidates 5 Years age relaxation
ii) For BC Candidates 5 Years age relaxation
iii) PHC Candidates 5 Years age relaxation

Category        Age    Valid/Invalid
----------------------------------------------
OC                 20       Invalid
OC                 21       Valid
OC                 35       Valid
OC                 36       Valid
BC                 36       Valid
BC                 39       Invalid
SC                 39       Valid
PHC               39       Valid
ST                 40       Valid
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Banking System interest rates For fixed deposits.
1 to 2 years 7%
2 to 3 Years 8%
3 to 5 Years 10%

Condition:

For Senior citizens 0.5% extra for all ranges

Age    Period    Interest Rate
-----------------------------------
25     1 year      7%
35     2.5          8%
56     4            10%
66     4            10.5%
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d) State Transition Testing
 

• In State transition Testing Test cases are designed to execute valid and invalid state transitions.

• A System (Application Under Test) may exhibit a different response on current conditions or previous history.

Example: Internet Banking System Fund Transfer operation

Initial Balance: 45000

Transaction 1    Transaction Amount        Transaction
1                       20000                            Successful (Pass)
2                       20000                            Successful (Pass)
3                       20000                            Unsuccessful (Pass)
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e) Use Case Testing
 

• In Use Case Testing Test Cases are designed to execute User Scenarios or Business Scenarios.

• A Use Case describes interactions between actors, including users and the system.

• A Use case usually has a mainstream scenario and sometimes alternative scenarios.

Example:

Business Scenario: ATM Cash Withdrawal operation

Mainstream Scenario:
 

1)
User: Inserts ATM Card

System: Asks for PIN

2)
User: Enters PIN

System: Validates PIN and asks to select language

3)
User: Selects Language

System: Asks to select Account Type

4)
User: Selects Account Type

System: Asks to enter Amount

5)
User: Enters Amount

System: Releases Money
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Alternatives
 

2a) Suppose if user enters invalid Pin

System: Shows error message and asks to enter correct PIN
User: Enters Correct PIN
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4a) Suppose if user selects incorrect Account Type

System: Shows error and asks to select correct Account Type
User: Select correct account type

5a) If User enters incorrect amount (More than the balance amount or more than the day limit)

System: Shows Error message and asks to enter correct amount
User: Enters correct amount
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4 comments:

Very impressive and easy for the beginners to grasp the concepts

Very impressive and easy for beginners to grasp concepts

OMG , i was thinking what is Alpha Bytes --- He means Alphabets.

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