Testing Techniques

Equivalence Class Partitioning

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Learning Outcome

Design test cases using ECP

Identify valid and invalid equivalence classes

Understand Equivalence Class Partitioning

Topic Name-Recall(Slide3)

Black box testing focuses on input and output

Equivalence Class Partitioning is one black box technique

In previous topic, we studied Black Box Testing

Hook/Story/Analogy(Slide 4)

A movie theatre sells tickets based on age:

Children: 0–12 years

Seniors: Above 60 years

Adults: 13–60 years

The ticket price is the same within each group

Step 1: Identify the Input

Input = Age of the person

Just like in software testing, age is the input value

Step 2: Form Groups (Equivalence Classes)

The theatre divides all possible ages into groups:

Class 1 (Valid): 0–12
Class 2 (Valid): 13–60
Class 3 (Valid): Above 60

Each group is an equivalence class because:

Everyone in that group is treated the same

Step 3: Why One Value Is Enough

If the system correctly charges:

Age = 10 → Child ticket
Age = 30 → Adult ticket
Age = 65 → Senior ticket

Then we assume:

All other ages in that same group will behave the same way

So:

Testing age 10 represents all ages 0–12
Testing age 30 represents all ages 13–60
Testing age 65 represents all ages above 60

Transition from Analogy to Technical Concept(Slide 5)

Why Black Box Techniques?

Source code knowledge is not required

Used during system and acceptance testing

Focuses on user requirements

Easy to apply in manual testing

Introduction to ECP

It divides input data into groups

Equivalence Class Partitioning is a Black Box Testing technique

Each group is treated as equivalent

Output

Input

Valid Equivalence class

Types of Equivalence Classes

Invalid Equivalence class

An equivalence class is a set of input values

One test case represents the entire class

System behaves the same for all values in the class

What is

Equivalence Class?

Valid Equivalence Class

Contains correct and acceptable input values
System should accept these values
Produces expected output

Invalid Equivalence Class

Contains incorrect or unacceptable input values
System should reject these values
Error message should be displayed

Steps to Apply ECP

Identify input conditions

Select one value from each class

Classify them as valid or invalid

Divide inputs into equivalence classes

Example

Condition:
Age must be between 18 and 60

Less than 18

18 to 60

Greater than 60

Valid Class

Invalid Class

Test Case 1

Test Case 2

Test Case 3

Test Case Design Using ECP

Age = 15 → Rejected

Age = 65 → Rejected

Age = 25 → Accepted

Advantages and Limitations of ECP

Reduces number of test cases

Easy to use in manual testing

Better coverage, less effort

Not suitable for complex logic

Often used with Boundary Value Analysis

Advantages

Limitations

Boundary values may be missed

Summary

Ensures good coverage with fewer test cases

Helps in efficient manual testing

ECP is an important black box testing technique

Quiz

The main purpose of Equivalence Class Partitioning is to:

A. Increase number of test cases

B. Reduce test execution time

C. Reduce number of test cases

D. Test internal code

Quiz

The main purpose of Equivalence Class Partitioning is to:

A. Increase number of test cases

B. Reduce test execution time

C. Reduce number of test cases

D. Test internal code

Testing Techniques

Equivalence Class Partitioning

Equivalence Class Partitioning

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