Add Ones & Twos Complement in BitManipulation (#5604)

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

@@ -0,0 +1,54 @@
+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"));
+    }
+}