Implementing Blackbox Testing

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Implementing Black Box Testing

Objectives
At the end of this session, you will be able to:
 Understand Software Testing
 Understand different types of Software Testing
 Understand Black Box Testing & White Box Testing
 Understand difference between Black Box and White Box Testing
 Implement Black Box Testing
» Equivalence Class Testing
» Boundary Value Analysis
» Decision Table Testing

www.edureka.co/software-testingSlide 3
What is Software Testing
Software Testing is the process of validating and verifying that a software application or product works as expected

Classification of Software Testing
Software Testing
Black Box Testing
White Box Testing
Unit Testing
Regression Testing
Integration Testing

Black Box Testing
Black box testing is a software testing technique in which functionality of the software is tested without looking
at the internal code structure
Black Box Testing can entirely be done on the basis of software requirements and specifications
In Black Box testing, tester tests the software/application by applying different inputs and comparing the
output with the expected result
Black Box
Input Output
Black Box Testing is also known as Behavioral Testing
Flow and Working

White Box Testing
White Box Testing is software testing technique based on analysis of internal logic (design, code, etc.). It’s
important to note that expected results still come from requirements
White Box Testing is usually done by developers and difficult as developers can't easily spot flaws in their own
code
Code coverage and Path testing are well known White Box Testing techniques
White Box Testing is also known as Structural Testing
White Box
Input Output
Design and code

Difference b/w Black Box and White Box Testing
Black Box
• Not Required
• Software Testers
• Not Required
• Requirement Specifications
White Box
• Required
• Software Developers
• Required
• Detail Design
Knowledge of internal
structure of test application
Responsibility
Programming Knowledge
Basis for Test Cases

Techniques of Black Box Testing
There are various techniques used to perform Black Box Testing. Some of them are listed below
Partition 1 Partition 2 Partition 3
10 10 11
Invalid Valid Invalid
1 10
Partition 1 Partition 2 Partition 3
Equivalence class partitioning
Boundary Value Analysis(BVA)
Decision Table Testing
Condition R1 R2 R3 R4
Input 1 F F T T
Input 2 F T F T
Action ERR ERR ERR GO

Equivalence Class Partitioning (ECP)
Usually its not possible to perform exhaustive testing when there is large test data either due to time or
budget constraints
Equivalence Class Partitioning is a very efficient technique used to cut down the number of test data to
test the application
Example
1 12<1 >12
Rather than testing the application for all number between 1 and 12, numbers <1 and >12, we can
partition test data into 3 sets, first for valid partition (1 -12), second for invalid partition (<1) and third
invalid partition (>12)
Test
Application
May, Sept

Applying Equivalence Class Partitioning
According to our example the test data can be partitioned into following classes
…, -3, -2, -1, 0 1, 2, 3…….., 12 13, 14, 15……..
Invalid Partition 1 Valid Partition Invalid Partition 2
Now to test the application tester can use any one number from each partition
So we can test the application with only three numbers (any one number from each partition)
Each number of a particular class partition will generate the same result. This is why this technique is called
Equivalence Class Partitioning

What about Boundaries?
Equivalence Class Partitioning does not guarantee to test the application on boundary values. It
gives the same weightage to both numbers within partition and numbers on the boundary
…, -3, -2, -1, 0 1, 2, 3…….., 12 13, 14, 15……..
What happens if the
test fails on the
boundary values?
To ensure that a tester tests the application on boundary
values also we can use Boundary Value Analysis technique

Boundary Value Analysis (BVA)
Decision boundaries are places where the behavior of the system changes
Boundary Value Analysis is an important technique as it is widely recognized that values on the boundaries
cause more errors in system
Therefore a tester should always check the boundaries as if the system fails, it is likely to fail on these decision
boundaries
[0,1] [12,13]<1 >12
It is very important that tester test the application on boundary values. Equivalence Partitioning and
Boundary Value Analysis are used together at all levels of testing e.g. unit testing, integration testing

Applying Boundary Value Analysis (BVA)
Consider the previous example where we partition the test data into three classes
In Boundary Value Analysis a tester must also check on boundary values in addition to other test data
Lets apply Boundary value Analysis to the previous example
…, -3, -2, -1, 0 1, 2, 3…….., 12 13, 14, 15……..
To apply BVA, we will take the minimum and maximum (boundary) values from the valid partition (1 and 12 in
this case) together with the first or last value respectively in each of the invalid partitions adjacent to the valid
partition (0 and 13 in this case)

ECP and BVA Together
According to the example we would have three equivalence partitioning tests (one from each of the three partitions)
and four boundary value tests
 To perform both Equivalence portioning and BVA tests a tester can use one of the below combination of test data
» [-3, 6, 20] (for equivalence partitioning tests ) and [0,1,12,13] (for boundary value tests)

 Decision Table Testing is a good way to deal with a combination
of inputs, which produce different results and are used to model
complicated logic
 It helps reduce test effort in verifying each and every
combination of test data, at the same time ensuring complete
coverage
The biggest advantage of using decision tables is that they make
it possible to detect combinations of conditions that would
otherwise not have been found and therefore not tested or
developed

Let’s take an example scenario for an ATM where a decision table would be of use
 A customer requests a cash withdrawal
 One of the business rules for the ATM is that the ATM machine pays out the amount if the customer has
sufficient funds in their account or if the customer has the credit granted. In a decision table, conditions are
usually expressed as true (T) or false (F)
Conditions R1 R2 R3
Withdrawal Amount <=
Balance
T F F
Credit granted - T F
Withdrawal granted T T F
Decision Table
Each column in the table corresponds to a
rule in the business logic that describes
the unique combination of circumstances
that will result in the actions

Lets consider another example of how we can model a scenario of book borrowing from college library
Conditions R1 R2 R3 R4 R5 R6 R7 R8
User Registered ? F F F F T T T T
No Pending Fees ? F F T T F F T T
Under Borrow Limit? F T F T F T F T
Borrow Book No No No No No No No Yes
User will only be allowed to borrow a book when user is registered, user does not have any outstanding fees
and he have not exceeded the book borrowing limit
If the user is not registered, then
the other two inputs are irrelevant

Simplifying Decision Tables
 Note that in our decision table we have 8 possible combinations but we can simplify the decision table by examining
the decision table and merging the similar combinations
Conditions R1 R2 R3 R4 R5
User Registered ? F T T T T
No Pending Fees ? - F F T T
Under Borrow Limit? - F T F T
Borrow Book No No No No Yes
If the user is having pending fees, then also he
cannot borrow books even if he has borrow limits
We have merged the first four columns
as the user is not registered

Simplifying Decision Tables (Contd.)
Again we can simplify the decision table as is does not matter whether user has borrow limit or not. If user has
pending fees, then the user can not borrow book
Conditions R1 R2 R3 R4
User Registered ? F T T T
No Pending Fees ? - F T T
Under Borrow Limit? - - F T
Borrow Book No No No Yes
We have merged the next two columns
as the user was having pending fees

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 Module 6
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 Module 7
» Defect Management
 Module 8
» Reporting & Team Collaboration
 Module 9
» Metrics & Measurement
 Module 10
» Testing Tools & FAQs
 Module 1
» Introduction to Software Testing Life Cycle
 Module 2
» Test Planning
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» Test Design
 Module 4
» Test Techniques
 Module 5
» Levels & Types Of Testing

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