Black-box testing techniques in Software Engineering - Mini Project: Build & Apply

Black-box Testing Techniques

📖 Scenario: You are part of a software testing team preparing to test a new calculator app. The app performs basic arithmetic operations like addition, subtraction, multiplication, and division.Your goal is to apply black-box testing techniques to design test cases without looking at the app's internal code.

🎯 Goal: Build a list of test cases using black-box testing techniques such as equivalence partitioning and boundary value analysis to ensure the calculator app works correctly for different inputs.

📋 What You'll Learn

Create a list of input categories for testing using equivalence partitioning

Define boundary values for each input category

Write test cases covering normal and edge inputs

Summarize the test cases in a structured format

💡 Why This Matters

🌍 Real World

Black-box testing helps testers find bugs without needing to understand the internal code, making it useful for testing software from a user's perspective.

💼 Career

Software testers and quality assurance engineers use black-box testing techniques daily to ensure software meets requirements and handles inputs correctly.

1

Define Input Categories Using Equivalence Partitioning

Create a list called input_categories with these exact string entries: 'positive numbers', 'negative numbers', 'zero', and 'non-numeric inputs'.

Software Engineering

# Create the list input_categories with the specified entries
# Your code here

Hint

Think about grouping inputs that should behave similarly in the calculator app.

2

Define Boundary Values for Each Input Category

Create a dictionary called boundary_values with keys matching each entry in input_categories. Assign these exact values:
'positive numbers': [1, 100],
'negative numbers': [-1, -100],
'zero': [0],
'non-numeric inputs': ['a', 'null'].

Software Engineering

input_categories = ['positive numbers', 'negative numbers', 'zero', 'non-numeric inputs']
# Create the dictionary boundary_values with the specified keys and values
# Your code here

Hint

Use a dictionary to map each category to its boundary test values.

3

Write Test Cases Covering Normal and Edge Inputs

Create a list called test_cases. Add dictionaries for each test case with keys 'input' and 'expected_behavior'. Include these exact test cases:
1. {'input': 1, 'expected_behavior': 'valid positive number'}
2. {'input': -1, 'expected_behavior': 'valid negative number'}
3. {'input': 0, 'expected_behavior': 'zero input'}
4. {'input': 'a', 'expected_behavior': 'invalid input error'}.

Software Engineering

input_categories = ['positive numbers', 'negative numbers', 'zero', 'non-numeric inputs']
boundary_values = {
    'positive numbers': [1, 100],
    'negative numbers': [-1, -100],
    'zero': [0],
    'non-numeric inputs': ['a', 'null']
}
# Create the list test_cases with the specified dictionaries
# Your code here

Hint

Each test case should describe what input you test and what you expect the app to do.

4

Summarize Test Cases in a Structured Format

Create a dictionary called test_summary with two keys: 'total_cases' set to the number of items in test_cases, and 'categories_tested' set to the list input_categories.

Software Engineering

input_categories = ['positive numbers', 'negative numbers', 'zero', 'non-numeric inputs']
boundary_values = {
    'positive numbers': [1, 100],
    'negative numbers': [-1, -100],
    'zero': [0],
    'non-numeric inputs': ['a', 'null']
}
test_cases = [
    {'input': 1, 'expected_behavior': 'valid positive number'},
    {'input': -1, 'expected_behavior': 'valid negative number'},
    {'input': 0, 'expected_behavior': 'zero input'},
    {'input': 'a', 'expected_behavior': 'invalid input error'}
]
# Create the dictionary test_summary with total_cases and categories_tested
# Your code here

Hint

Summarize your test cases by counting them and listing the categories tested.