Calculator Application - Testing Lab

A learning project demonstrating unit testing with JUnit 5, focusing on statement coverage and path coverage testing.

Project Structure

.
├── src/
│   ├── main/java/com/example/
│   │   └── Calculator.java
│   └── test/java/com/example/
│       ├── CalculatorStatementCoverageTest.java
│       └── CalculatorPathCoverageTest.java
├── pom.xml
├── ISSUE_1.md
├── ISSUE_2.md
└── README.md

Calculator Class

The Calculator class contains three main methods with loops and branching logic:

1. calculateSum(int n)

• Calculates the sum of numbers from 1 to n
• Even numbers are doubled before adding
• Throws IllegalArgumentException if n is negative
• Loops: for loop iterating from 1 to n
• Branching: if-else checking even/odd

2. categorizeNumber(int num)

• Categorizes a number as positive/negative, even/odd, or zero
• Returns a descriptive string
• Branching: Multiple nested if-else statements

3. countOccurrences(int[] arr, int target)

• Counts how many times a target number appears in an array
• Stops counting if count exceeds 100
• Loops: for-each loop through array
• Branching: if statements for null check, matching, and break condition

Test Cases

Issue #1: Statement Coverage (16 tests)

CalculatorStatementCoverageTest.java ensures every line of code is executed:

• Tests cover all methods and all branches
• Includes edge cases and exception handling
• Verifies correctness of each statement

Test Methods:

• testCalculateSumWithZero()
• testCalculateSumWithOne()
• testCalculateSumWithTwo()
• testCalculateSumWithFive()
• testCalculateSumWithNegative()
• testCategorizePositiveOdd()
• testCategorizePositiveEven()
• testCategorizeNegativeOdd()
• testCategorizeNegativeEven()
• testCategorizeZero()
• testCountOccurrencesWithNull()
• testCountOccurrencesWithEmpty()
• testCountOccurrencesNoMatch()
• testCountOccurrencesSingleMatch()
• testCountOccurrencesMultipleMatches()
• testCountOccurrencesBreakCondition()

Issue #2: Path Coverage (27 tests)

CalculatorPathCoverageTest.java ensures all execution paths are tested:

• Tests all decision branches
• Covers nested conditions
• Tests boundary values

Path Coverage by Method:

• calculateSum(): 5 paths
• categorizeNumber(): 5 paths
• countOccurrences(): 5 paths
• Plus comprehensive and boundary tests

Running Tests

With Maven:

mvn clean test

With IDE:

Run the test classes directly from your IDE (IntelliJ IDEA, Eclipse, VS Code).

With Java Compiler:

# Compile
javac -d target/classes src/main/java/com/example/Calculator.java

# Compile tests (requires JUnit 5 in classpath)
javac -cp target/classes:junit-jupiter-api-5.9.3.jar:junit-jupiter-engine-5.9.3.jar \
  -d target/test-classes \
  src/test/java/com/example/CalculatorStatementCoverageTest.java

Pushing to GitHub

To push this repository to GitHub:

1. Create a new repository on GitHub

• Go to https://github.com/new
• Name your repository (e.g., calculator-testing-lab)
• Choose public or private
• DO NOT initialize with README (we have one)

2. Connect local repo to remote

git remote add origin https://github.com/YOUR_USERNAME/calculator-testing-lab.git
git branch -M main
git push -u origin main

3. Verify on GitHub

• Check that all commits are visible
• Issues #1 and #2 are documented in ISSUE_1.md and ISSUE_2.md

Learning Objectives

This lab demonstrates:

1. ✅ Writing code with loops and conditional branching
2. ✅ Creating comprehensive unit tests with JUnit 5
3. ✅ Understanding statement coverage (C1 coverage)
4. ✅ Understanding path coverage (decision coverage)
5. ✅ Using Git for version control
6. ✅ Following TDD and testing best practices

Coverage Metrics

The test suite achieves:

• Statement Coverage: 100% (every statement executed)
• Branch Coverage: 100% (every decision taken both ways)
• Path Coverage: 100% (all execution paths tested)

Dependencies

• Java 11+
• JUnit Jupiter (JUnit 5) 5.9.3
• Maven 3.6+ (optional, for building)

References

• JUnit 5 Documentation
• Code Coverage Techniques
• Git Documentation