Added Ones & Twos Complement test cases

Author: Monk-AbhinayVerma

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

@@ -0,0 +1,57 @@
+package com.thealgorithms.bitmanipulation;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import org.junit.jupiter.api.Test;
+
+/**
+ * Test case for Highest Set Bit
+ * 
+ * @author Abhinay Verma(https://github.com/Monk-AbhinayVerma)
+ */
+public class OnesComplementTest {
+
+    @Test
+    public void testOnesComplement_AllZeroes() {
+
+        // Test cases with all-zero binary strings
+        assertEquals("1111", OnesComplement.onesComplement("0000"));
+        assertEquals("111", OnesComplement.onesComplement("000"));
+        assertEquals("11", OnesComplement.onesComplement("00"));
+        assertEquals("1", OnesComplement.onesComplement("0"));
+    }
+
+    @Test
+    public void testOnesComplement_AllOnes() {
+        // Test cases with all-one binary strings
+        assertEquals("0000", OnesComplement.onesComplement("1111"));
+        assertEquals("000", OnesComplement.onesComplement("111"));
+        assertEquals("00", OnesComplement.onesComplement("11"));
+        assertEquals("0", OnesComplement.onesComplement("1"));
+    }
+
+    @Test
+    public void testOnesComplement_MixedBits() {
+        // Test more mixed binary patterns
+        assertEquals("1010", OnesComplement.onesComplement("0101"));
+        assertEquals("0101", OnesComplement.onesComplement("1010"));
+        assertEquals("1100", OnesComplement.onesComplement("0011"));
+        assertEquals("0011", OnesComplement.onesComplement("1100"));
+        assertEquals("1001", OnesComplement.onesComplement("0110"));
+    }
+
+    @Test
+    public void testOnesComplement_EmptyString() {
+        // Test empty string scenario
+        assertEquals("", OnesComplement.onesComplement(""));
+    }
+
+    @Test
+    public void testOnesComplement_InvalidInput() {
+        // Test invalid binary strings with additional non-binary characters
+        assertThrows(IllegalArgumentException.class, () -> OnesComplement.onesComplement("1020"));
+        assertThrows(IllegalArgumentException.class, () -> OnesComplement.onesComplement("abc"));
+        assertThrows(IllegalArgumentException.class, () -> OnesComplement.onesComplement("12"));
+    }
+}

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

@@ -0,0 +1,62 @@
+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 testTwosComplement_AllZeroes() {
+        // Test with a binary number consisting entirely of zeroes
+        assertEquals("0000", TwosComplement.twosComplement("0000"));
+        assertEquals("000", TwosComplement.twosComplement("000"));
+        assertEquals("00", TwosComplement.twosComplement("00"));
+        assertEquals("0", TwosComplement.twosComplement("0"));
+    }
+
+    @Test
+    public void testTwosComplement_AllOnes() {
+        // Test with a binary number consisting entirely of ones
+        assertEquals("11111", TwosComplement.twosComplement("11111")); // Extra '1' due to carry
+        assertEquals("1111", TwosComplement.twosComplement("1111"));
+        assertEquals("111", TwosComplement.twosComplement("111"));
+        assertEquals("11", TwosComplement.twosComplement("11"));
+    }
+
+    @Test
+    public void testTwosComplement_MixedBits() {
+        // Test with binary numbers with mixed bits
+        assertEquals("1110", TwosComplement.twosComplement("0001")); // 1's complement: 1110, then add 1: 1111
+        assertEquals("1000", 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 testTwosComplement_SingleBit() {
+        // Test with single bit
+        assertEquals("1", TwosComplement.twosComplement("0"));
+        assertEquals("11", TwosComplement.twosComplement("1")); // 1's complement: 0, add 1: 1, carry generates extra
+                                                                // '1'
+    }
+
+    @Test
+    public void testTwosComplement_EmptyString() {
+        // Test with an empty string
+        assertEquals("", TwosComplement.twosComplement(""));
+    }
+
+    @Test
+    public void testTwosComplement_WithLeadingZeroes() {
+        // Test with leading zeroes in the input
+        assertEquals("1111", TwosComplement.twosComplement("0001"));
+        assertEquals("100", TwosComplement.twosComplement("011"));
+        assertEquals("101", TwosComplement.twosComplement("010"));
+    }
+}