Boundary value Analysis (BVA) & Equivalence Partitioning (EP)


1. Boundary Value Analysis (BVA)

Definition

Boundary Value Analysis is a software testing technique used to test the values at the boundaries or edges of input ranges, because errors are most likely to occur at the boundary limits.

What is Boundary Value Analysis?

BVA focuses on minimum, maximum, and edge values of input ranges instead of testing every possible value.

Example:
If the valid input range is 1–100, boundary values are:

  • 0 (below minimum)

  • 1 (minimum)

  • 2 (just above minimum)

  • 99 (just below maximum)

  • 100 (maximum)

  • 101 (above maximum)

Why is Boundary Value Analysis Used?

Boundary testing is used because most errors occur at boundary limits.

Reasons:

  • Reduces number of test cases

  • Finds edge-case bugs

  • Improves testing efficiency

When is Boundary Value Analysis Used?

BVA is used when:

  • Input values have specific ranges

  • Forms accept numbers, age, marks, quantity, etc.

Example:

  • Age field (18–60)

  • Marks field (0–100)

Where is Boundary Value Analysis Used?

It is commonly used in:

  • Login forms

  • Online registration forms

  • Banking systems

  • E-commerce quantity fields

  • Exam marks systems

How Boundary Value Analysis Works

Steps:

  1. Identify input range

  2. Identify minimum and maximum values

  3. Create test cases around the boundaries

  4. Test values below, at, and above the boundary

Example:
Age field range 18–60

Test cases:

  • 17 (below minimum)

  • 18 (minimum)

  • 19 (just above minimum)

  • 59 (just below maximum)

  • 60 (maximum)

  • 61 (above maximum)

2. Equivalence Partitioning (EP)

Definition

Equivalence Partitioning is a software testing technique where input data is divided into valid and invalid partitions, and one value from each partition is tested.

What is Equivalence Partitioning?

Instead of testing every input value, inputs are divided into groups (partitions) that behave the same.

Only one value from each group is tested.

Example:
Marks range 0–100

Partitions:

  • Invalid partition → less than 0

  • Valid partition → 0–100

  • Invalid partition → greater than 100

Why is Equivalence Partitioning Used?

EP helps to:

  • Reduce number of test cases

  • Save testing time

  • Improve testing coverage

When is Equivalence Partitioning Used?

It is used when:

  • Inputs have large number of possible values

  • Testing input fields or form validations

Example:

  • Marks input

  • Password field

  • Quantity input

Where is Equivalence Partitioning Used?

Commonly used in:

  • Web form validation

  • Login systems

  • Student result systems

  • Online registration forms

How Equivalence Partitioning Works

Steps:

  1. Identify input field

  2. Divide input values into valid and invalid groups

  3. Select one value from each group

  4. Test the application using those values

Example:
Marks field 0–100

Test cases:

  • -5 → invalid partition

  • 50 → valid partition

  • 110 → invalid partition

Difference Between BVA and Equivalence Partitioning

FeatureBoundary Value AnalysisEquivalence Partitioning
FocusEdge valuesGroups of values
Test casesMinimum and maximum valuesOne value per group
PurposeFind boundary errorsReduce test cases


  • BVA: Tests boundary limits of input ranges.

  • EP: Divides input data into valid and invalid partitions

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