Boundary value analysis in Testing Fundamentals - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Identify boundary values for input range

Consider a function that accepts an integer input between 10 and 50 inclusive. Which set correctly represents the boundary values for testing?

A 9, 10, 11, 49, 50, 51

B 10, 20, 30, 40, 50

C 11, 25, 49

D 9, 15, 35, 51

💡 Hint

Boundary values include the edges and just outside the edges of the input range.

Boundary value analysis tests the edges of input ranges. For 10 to 50 inclusive, test values just below 10 (9), at 10, just above 10 (11), just below 50 (49), at 50, and just above 50 (51).

❓ Predict Output

intermediate

Output of boundary test function

What is the output of the following Python function when called with input 100?

Testing Fundamentals

def test_input(x):
    if x < 1 or x > 100:
        return "Invalid"
    elif x == 1 or x == 100:
        return "Boundary"
    else:
        return "Normal"

result = test_input(100)
print(result)

A Error

B Normal

C Boundary

D Invalid

💡 Hint

Check the conditions for input equal to 100.

The function returns "Boundary" if input is exactly 1 or 100. Since input is 100, output is "Boundary".

❓ assertion

advanced

Assertion for boundary value test

Which assertion correctly tests that a function validate_age returns true for the boundary age 18?

Testing Fundamentals

def validate_age(age):
    return 18 <= age <= 65

A assert validate_age(18) == False

B assert validate_age(18) is False

C assert validate_age(18) != True

D assert validate_age(18) == True

💡 Hint

Check the function logic for age 18.

The function returns true if age is between 18 and 65 inclusive. So for age 18, it returns true. The assertion must check for true.

🔧 Debug

advanced

Find the boundary test bug

Given this test code for a function is_valid_score that accepts scores 0 to 100 inclusive, which option shows the bug causing a boundary test to fail?

Testing Fundamentals

def is_valid_score(score):
    return 0 <= score < 100

assert is_valid_score(100) == True

A The function excludes 100, so assert fails because 100 is not valid

B The function includes 100, so assert fails due to wrong logic

C The assert syntax is wrong, causing failure

D The function accepts negative scores, causing failure

💡 Hint

Check the comparison operators in the function.

The function uses < 100, so 100 is excluded. The assert expects true for 100, causing failure.

❓ framework

expert

Design boundary tests in pytest

Which pytest test function correctly tests the boundary values for a function check_temperature that accepts temperatures from -20 to 50 inclusive?

Testing Fundamentals

def check_temperature(temp):
    return -20 <= temp <= 50

A

import pytest
@pytest.mark.parametrize('temp', [-20, 0, 50])
def test_temp(temp):
    assert check_temperature(temp) == True

B

import pytest
@pytest.mark.parametrize('temp', [-21, -20, -19, 49, 50, 51])
def test_temp(temp):
    expected = temp >= -20 and temp <= 50
    assert check_temperature(temp) == expected

C

import pytest
@pytest.mark.parametrize('temp', [-21, 51])
def test_temp(temp):
    assert check_temperature(temp) == False

D

import pytest
def test_temp():
    assert check_temperature(-20) and check_temperature(50)

💡 Hint

Boundary tests include just outside and on the edges of the valid range.

Option B tests values just below, at, just above boundaries and asserts expected results correctly. Others miss some boundary or do not test both valid and invalid cases.

Practice

1. What is the main goal of Boundary Value Analysis in software testing?

easy

A. To test the software's user interface design

B. To test inputs at the edges of input ranges

C. To test the software's performance under load

D. To test only the middle values of input ranges

Solution

1. Step 1: Understand boundary value analysis purpose

   Boundary value analysis focuses on testing the edges or limits of input ranges where errors often occur.

2. Step 2: Compare options with definition

   Only To test inputs at the edges of input ranges correctly describes testing inputs at the edges of input ranges.

3. Final Answer:

   To test inputs at the edges of input ranges -> Option B

4. Quick Check:

   Boundary value analysis = test edges [OK]

Hint: Focus on testing minimum and maximum input values [OK]

Common Mistakes:

• Confusing boundary testing with performance testing
• Testing only middle values instead of edges
• Ignoring values just outside the boundaries

2. Which of the following is the correct set of test inputs for boundary value analysis of an input field that accepts values from 1 to 10?

easy

A. 1, 5, 10

B. 0, 5, 10

C. 2, 5, 9

D. 0, 1, 10, 11

Solution

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

   Boundaries are minimum (1) and maximum (10). Values just outside are 0 and 11.

2. Step 2: Check options for boundary and just outside values

   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 D

4. Quick Check:

   Include min, max, and just outside values [OK]

Hint: Always test min, max, and values just outside boundaries [OK]

Common Mistakes:

• Testing only valid values inside the range
• Ignoring values just outside the boundaries
• Choosing random values without boundary focus

3. Consider a function that accepts an integer input from 5 to 15 inclusive. Which of the following test inputs is NOT a valid boundary value test case?

medium

A. 10

B. 5

C. 4

D. 15

Solution

1. Step 1: Identify boundary values and just outside values

   Boundaries are 5 (min) and 15 (max). Just outside are 4 and 16.

2. Step 2: Check which input is not a boundary or just outside value

   Inputs 4, 5, and 15 are boundary or just outside values. 10 is a normal middle value, not a boundary test case.

3. Final Answer:

   10 -> Option A

4. Quick Check:

   Boundary tests exclude middle values like 10 [OK]

Hint: Exclude middle values; test edges and just outside only [OK]

Common Mistakes:

• Including middle values as boundary tests
• Ignoring values just outside boundaries
• Confusing valid inputs with boundary inputs

4. A tester wrote these boundary test inputs for a field accepting values 10 to 20: 9, 10, 20, 21. The test failed for input 21. What is the most likely reason?

medium

A. The software has a bug accepting 21

B. The test inputs are incorrect; 21 should be accepted

C. 21 is outside the valid input range and should fail

D. Boundary value analysis does not require testing outside the range

Solution

1. Step 1: Understand boundary test inputs and expected behavior

   Inputs 9 and 21 are just outside the valid range 10 to 20, so failure on 21 is expected.

2. Step 2: Analyze test failure reason

   Since 21 is invalid input, failure means software correctly rejects it. So test failure is expected, not a bug.

3. Final Answer:

   21 is outside the valid input range and should fail -> Option C

4. Quick Check:

   Outside boundary inputs should cause failure [OK]

Hint: Expect failure for inputs just outside boundaries [OK]

Common Mistakes:

• Thinking failure on invalid input is a bug
• Not testing values just outside boundaries
• Assuming all test inputs must pass

5. A form accepts age input from 18 to 60 inclusive. Using boundary value analysis, which set of test inputs covers all necessary boundary cases including just outside values?

hard

A. 17, 18, 60, 61

B. 18, 30, 60

C. 16, 18, 59, 61

D. 18, 19, 59, 60

Solution

1. Step 1: Identify boundary and just outside values for age 18 to 60

   Boundaries are 18 (min) and 60 (max). Just outside are 17 (below min) and 61 (above max).

2. Step 2: Check which option includes all boundaries and just outside values

   17, 18, 60, 61 includes 17, 18, 60, and 61, covering all required boundary and just outside values.

3. Final Answer:

   17, 18, 60, 61 -> Option A

4. Quick Check:

   Test min, max, and just outside values for full coverage [OK]

Hint: Always include min, max, and one value outside each boundary [OK]

Common Mistakes:

• Missing just outside boundary values
• Testing only valid inputs inside range
• Confusing boundary values with random inputs