@Test void testDivide() { assertEquals(2, calculator.divide(10, 5), "Division failed"); }

@Test void testAdd() { assertEquals(15, calculator.add(10, 5), "Addition failed"); }

@Test void testSubtract() { assertEquals(5, calculator.subtract(10, 5), "Subtraction failed"); }

// src/main/java/com/example/Calculator.java

@Test void testMultiply() { assertEquals(50, calculator.multiply(10, 5), "Multiplication failed"); }

public class App {

public double multiply(double a, double b) { return a * b; }

// src/main/java/com/example/App.java