IntOperationTest.java

package com.examplehub.basics.ints;

import static org.junit.jupiter.api.Assertions.*;

import org.junit.jupiter.api.Test;

class IntOperationTest {
  @Test
  void testAdd() {
    assertEquals(10, 5 + 5);
    assertEquals(0, 10 + (-10));
    assertEquals(-2147483641, 2147483640 + 15);
  }

  @Test
  void testDivide() {
    assertEquals(2, 10 / 5);
    assertEquals(5, 10 / 2);
    assertEquals(2, 7 / 3);
    assertEquals(164, 12345 / 75);

    assertThrows(
        ArithmeticException.class,
        () -> {
          int division = 10 / 0;
        });
  }

  @Test
  void testRemainder() {
    assertEquals(1, 10 % 3);
    assertEquals(1, 31 % 3);
    assertEquals(1, 1 % 2);
    assertEquals(0, 10 % 5);
  }

  @Test
  void testIncrement() {
    int age = 10;
    assertEquals(11, ++age);
    assertEquals(11, age++);
    assertEquals(12, age);
  }

  @Test
  void testDecrement() {
    int age = 10;
    assertEquals(9, --age);
    assertEquals(9, age--);
    assertEquals(8, age);
  }

  @Test
  void testBitwiseRightShift() {
    int num = 7; // 00000000 00000000 00000000 00000111 = 7
    int a = num << 1; // 00000000 00000000 00000000 00001110 = 14
    assertEquals(14, a);

    int b = num << 2; // 00000000 00000000 00000000 00011100 = 28
    assertEquals(28, b);

    int c = num << 28; // 01110000 00000000 00000000 00000000 = 1879048192
    assertEquals(1879048192, c);

    int d = num << 29; // 11100000 00000000 00000000 00000000 = -536870912
    assertEquals(-536870912, d);
  }

  @Test
  void testBitwiseLeftShift() {
    int num = -536870912;
    int a = num >> 1; // 11110000 00000000 00000000 00000000 = -268435456
    assertEquals(-268435456, a);

    int b = num >> 2; // 11111000 00000000 00000000 00000000 = -134217728
    assertEquals(-134217728, b);

    int c = num >> 28; // 11111111 11111111 11111111 11111110 = -2
    assertEquals(-2, c);

    int d = num >> 29; // 11111111 11111111 11111111 11111111 = -1
    assertEquals(-1, d);
  }
}