Add 2P-Set (Two-Phase Set) for both addition and removal operations in distributed systems (#4977)

src/test/java/com/thealgorithms/datastructures/crdt/TwoPSetTest.java

@@ -0,0 +1,68 @@
+package com.thealgorithms.datastructures.crdt;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+class TwoPSetTest {
+
+    private TwoPSet set;
+
+    @BeforeEach
+    void setUp() {
+        set = new TwoPSet();
+    }
+
+    @Test
+    void testLookup() {
+        set.add("A");
+        assertTrue(set.lookup("A"));
+        assertFalse(set.lookup("B"));
+        set.remove("A");
+        assertFalse(set.lookup("A"));
+    }
+
+    @Test
+    void testAdd() {
+        set.add("A");
+        assertTrue(set.lookup("A"));
+    }
+
+    @Test
+    void testRemove() {
+        set.add("A");
+        set.remove("A");
+        assertFalse(set.lookup("A"));
+    }
+
+    @Test
+    void testCompare() {
+        TwoPSet set1 = new TwoPSet();
+        set1.add("A");
+        set1.add("B");
+        TwoPSet set2 = new TwoPSet();
+        set2.add("A");
+        assertFalse(set1.compare(set2));
+        set2.add("B");
+        assertTrue(set1.compare(set2));
+        set1.remove("A");
+        assertFalse(set1.compare(set2));
+        set2.remove("A");
+        assertTrue(set1.compare(set2));
+    }
+
+    @Test
+    void testMerge() {
+        TwoPSet set1 = new TwoPSet();
+        set1.add("A");
+        set1.add("B");
+        TwoPSet set2 = new TwoPSet();
+        set2.add("B");
+        set2.add("C");
+        TwoPSet mergedSet = set1.merge(set2);
+        assertTrue(mergedSet.lookup("A"));
+        assertTrue(mergedSet.lookup("B"));
+        assertTrue(mergedSet.lookup("C"));
+    }
+}