Java テスト クラスでメソッドを呼び出すための手法を改善する

public class Calculator {
    public static int add(int a, int b) {
        return a + b;
    }
    
    public static int subtract(int a, int b) {
        return a - b;
    }
}

import org.junit.Test;
import static org.junit.Assert.assertEquals;

public class CalculatorTest {
    @Test
    public void testAdd() {
        int result = Calculator.add(2, 3);
        assertEquals(5, result);
    }
    
    @Test
    public void testSubtract() {
        int result = Calculator.subtract(5, 2);
        assertEquals(3, result);
    }
}

public class CalculatorTest {
    public static void main(String[] args) {
        int result1 = Calculator.add(2, 3);
        System.out.println("2 + 3 = " + result1);
        
        int result2 = Calculator.subtract(5, 2);
        System.out.println("5 - 2 = " + result2);
    }
}

import java.lang.reflect.Method;

public class CalculatorTest {
    public static void main(String[] args) throws Exception {
        Class<?> clazz = Class.forName("Calculator");
        
        Method addMethod = clazz.getDeclaredMethod("add", int.class, int.class);
        int result1 = (int)addMethod.invoke(null, 2, 3);
        System.out.println("2 + 3 = " + result1);
        
        Method subtractMethod = clazz.getDeclaredMethod("subtract", int.class, int.class);
        int result2 = (int)subtractMethod.invoke(null, 5, 2);
        System.out.println("5 - 2 = " + result2);
    }
}