Java/src/test/java/com/thealgorithms/bitmanipulation/TwosComplementTest.java

package com.thealgorithms.bitmanipulation;

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

import org.junit.jupiter.api.Test;

/**
 * Test case for Highest Set Bit
 * @author Abhinay Verma(https://github.com/Monk-AbhinayVerma)
 */
public class TwosComplementTest {

    @Test
    public void testTwosComplementAllZeroes() {
        // Test with a binary number consisting entirely of zeroes
        assertEquals("10000", TwosComplement.twosComplement("0000"));
        assertEquals("1000", TwosComplement.twosComplement("000"));
        assertEquals("100", TwosComplement.twosComplement("00"));
        assertEquals("10", TwosComplement.twosComplement("0"));
    }

    @Test
    public void testTwosComplementAllOnes() {
        // Test with a binary number consisting entirely of ones
        assertEquals("00001", TwosComplement.twosComplement("11111"));
        assertEquals("0001", TwosComplement.twosComplement("1111"));
        assertEquals("001", TwosComplement.twosComplement("111"));
        assertEquals("01", TwosComplement.twosComplement("11"));
    }

    @Test
    public void testTwosComplementMixedBits() {
        // Test with binary numbers with mixed bits
        assertEquals("1111", TwosComplement.twosComplement("0001")); // 1's complement: 1110, then add 1: 1111
        assertEquals("1001", TwosComplement.twosComplement("0111")); // 1's complement: 1000
        assertEquals("11001", TwosComplement.twosComplement("00111")); // 1's complement: 11000, add 1: 11001
        assertEquals("011", TwosComplement.twosComplement("101")); // 1's complement: 010, add 1: 011
    }

    @Test
    public void testTwosComplementSingleBit() {
        // Test with single bit
        assertEquals("10", TwosComplement.twosComplement("0"));
        assertEquals("1", TwosComplement.twosComplement("1"));
    }

    @Test
    public void testTwosComplementWithLeadingZeroes() {
        // Test with leading zeroes in the input
        assertEquals("1111", TwosComplement.twosComplement("0001"));
        assertEquals("101", TwosComplement.twosComplement("011"));
        assertEquals("110", TwosComplement.twosComplement("010"));
    }
}