Equivalence partitioning and boundary value analysis in Software Engineering - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is equivalence partitioning in software testing?

Equivalence partitioning is a testing technique that divides input data into groups where test cases from each group are expected to behave similarly. It helps reduce the number of test cases while covering all possible scenarios.

beginner

Explain boundary value analysis (BVA).

Boundary value analysis tests the values at the edges of input ranges because errors often happen at these boundaries. It focuses on minimum, maximum, just inside/outside boundaries to catch edge case bugs.

intermediate

Why do testers use equivalence partitioning and boundary value analysis together?

Testers combine these techniques to efficiently cover input scenarios. Equivalence partitioning reduces test cases by grouping inputs, while boundary value analysis ensures edge cases are tested where bugs often occur.

beginner

Give an example of equivalence partitions for an input field accepting ages 18 to 60.

Partitions could be: invalid low (below 18), valid (18 to 60), and invalid high (above 60). Each group represents inputs expected to behave the same way in the system.

beginner

What test inputs would boundary value analysis suggest for the age range 18 to 60?

Test inputs would be 17 (just below min), 18 (min), 19 (just above min), 59 (just below max), 60 (max), and 61 (just above max). These check behavior at and near boundaries.

What is the main goal of equivalence partitioning?

A To test the software's performance under load

B To test only the maximum input value

C To reduce the number of test cases by grouping similar inputs

D To write code for input validation

Equivalence partitioning groups inputs that should behave the same, reducing test cases while covering scenarios.

Which values are most important in boundary value analysis?

A Values at and near the edges of input ranges

B Only the minimum value

C Random values inside the input range

D Only invalid inputs

Boundary value analysis focuses on edge values because errors often occur there.

If an input accepts numbers 1 to 100, which is NOT a boundary value test input?

A 1

B 50

C 100

D 0

50 is inside the range but not near a boundary; boundary tests focus on edges like 1, 100, and just outside values like 0.

How many equivalence partitions are there for an input that accepts values 10 to 20?

A 1

B 2

C 4

D 3

There are three partitions: below 10 (invalid), 10 to 20 (valid), above 20 (invalid).

Why is boundary value analysis effective in finding bugs?

A Because developers often make mistakes at input limits

B Because it tests all possible inputs

C Because it ignores invalid inputs

D Because it only tests valid inputs

Errors frequently happen at boundaries, so testing these values catches common bugs.

Describe how you would apply equivalence partitioning and boundary value analysis to test a form field that accepts numbers from 1 to 50.

Think about grouping inputs and testing edges.

Explain why combining equivalence partitioning and boundary value analysis improves test coverage and efficiency.

Consider how each technique complements the other.

Practice

1. Which of the following best describes equivalence partitioning in software testing?

easy

A. Running all possible input combinations exhaustively

B. Testing only the maximum input value of a range

C. Checking the software's response to invalid inputs only

D. Dividing input data into groups where test cases represent each group

Solution

1. Step 1: Understand equivalence partitioning concept

   Equivalence partitioning divides inputs into groups where all inputs in a group are expected to behave similarly.

2. Step 2: Match description to options

   Dividing input data into groups where test cases represent each group correctly states this grouping approach. Other options describe different testing ideas.

3. Final Answer:

   Dividing input data into groups where test cases represent each group -> Option D

4. Quick Check:

   Equivalence partitioning = Group inputs [OK]

Hint: Group inputs by behavior to reduce tests [OK]

Common Mistakes:

• Confusing equivalence partitioning with boundary value analysis
• Thinking it tests only invalid inputs
• Assuming it requires exhaustive testing

2. Which of the following is the correct boundary value test inputs for a field accepting integers from 1 to 10 inclusive?

easy

A. 1, 2, 9, 10

B. 1, 5, 10

C. 0, 1, 10, 11

D. 0, 5, 10

Solution

1. Step 1: Identify boundary values for range 1 to 10

   Boundaries are the edges: minimum (1), maximum (10), and just outside edges (0 and 11).

2. Step 2: Check options for correct boundary inputs

   0, 1, 10, 11 includes 0 (just below min), 1 (min), 10 (max), and 11 (just above max), which is correct for boundary testing.

3. Final Answer:

   0, 1, 10, 11 -> Option C

4. Quick Check:

   Boundary values = edges and just outside [OK]

Hint: Test edges plus one inside and outside values [OK]

Common Mistakes:

• Testing only valid inputs ignoring just outside boundaries
• Choosing random middle values instead of edges
• Missing one side of the boundary

3. Consider a function that accepts an integer input from 1 to 5 inclusive. Which set of test inputs covers both equivalence partitioning and boundary value analysis?

medium

A. [0, 1, 3, 5, 6]

B. [1, 2, 3, 4, 5]

C. [1, 5]

D. [2, 3, 4]

Solution

1. Step 1: Identify equivalence partitions and boundaries

   Partitions: invalid below (<=0), valid (1-5), invalid above (>=6). Boundaries: 1 and 5 plus just outside 0 and 6.

2. Step 2: Check which option covers all partitions and boundaries

   [0, 1, 3, 5, 6] includes 0 (below), 1 (min boundary), 3 (valid middle), 5 (max boundary), and 6 (above), covering partitions and boundaries.

3. Final Answer:

   [0, 1, 3, 5, 6] -> Option A

4. Quick Check:

   Partitions + boundaries = test edges and groups [OK]

Hint: Include invalid, valid, and boundary values [OK]

Common Mistakes:

• Ignoring invalid partitions
• Testing only boundaries without middle values
• Choosing only valid inputs

4. A tester wrote these test inputs for a field accepting values 10 to 20 inclusive: [9, 10, 15, 20, 21]. The test failed to catch a bug at input 21. What is the likely mistake?

medium

A. They only tested valid inputs and ignored invalid ones

B. They did not include invalid inputs below 10

C. They missed testing the exact boundary values

D. They did not test the boundary just above the max value correctly

Solution

1. Step 1: Analyze test inputs and bug location

   Inputs include 9 (below min), 10 (min), 15 (middle), 20 (max), and 21 (just above max). Bug at 21 means boundary above max was tested.

2. Step 2: Identify mistake causing bug miss

   Since bug was missed at 21, likely the test did not properly check or handle the boundary just above max, possibly due to incorrect validation or test setup.

3. Final Answer:

   They only tested valid inputs and ignored invalid ones -> Option A

4. Quick Check:

   Boundary above max must be tested carefully [OK]

Hint: Check boundaries just outside valid range carefully [OK]

Common Mistakes:

• Assuming testing 21 is enough without checking handling
• Ignoring off-by-one errors at boundaries
• Not validating test setup correctness

5. You have a form field that accepts ages from 18 to 60 inclusive. Using equivalence partitioning and boundary value analysis, which of the following test sets is the most effective to detect input errors?

hard

A. [18, 19, 20, 59, 60]

B. [17, 18, 30, 60, 61]

C. [18, 30, 60]

D. [16, 18, 60, 62]

Solution

1. Step 1: Define equivalence partitions and boundaries for age 18-60

   Partitions: invalid below 18, valid 18-60, invalid above 60. Boundaries: 18 (min), 60 (max), and just outside 17 and 61.

2. Step 2: Evaluate options for coverage

   [17, 18, 30, 60, 61] includes 17 (below min), 18 (min), 30 (valid middle), 60 (max), and 61 (above max), covering all partitions and boundaries effectively.

3. Final Answer:

   [17, 18, 30, 60, 61] -> Option B

4. Quick Check:

   Test invalid, valid, and boundary values for best coverage [OK]

Hint: Test just below, at, inside, and just above boundaries [OK]

Common Mistakes:

• Ignoring invalid partitions
• Testing only valid inputs
• Missing boundary values just outside range