Add LWW Element Set (Last Write Wins Element Set) (#4979)

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

@@ -0,0 +1,107 @@
+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 LWWElementSetTest {
+
+    private LWWElementSet set;
+    private final Bias bias = Bias.ADDS;
+
+    @BeforeEach
+    void setUp() {
+        set = new LWWElementSet();
+    }
+
+    @Test
+    void testAdd() {
+        Element element = new Element("key1", 1, bias);
+        set.add(element);
+
+        assertTrue(set.lookup(element));
+    }
+
+    @Test
+    void testRemove() {
+        Element element = new Element("key1", 1, bias);
+        set.add(element);
+        set.remove(element);
+
+        assertFalse(set.lookup(element));
+    }
+
+    @Test
+    void testRemoveNonexistentElement() {
+        Element element = new Element("key1", 1, bias);
+        set.remove(element);
+
+        assertFalse(set.lookup(element));
+    }
+
+    @Test
+    void testLookupNonexistentElement() {
+        Element element = new Element("key1", 1, bias);
+
+        assertFalse(set.lookup(element));
+    }
+
+    @Test
+    void testCompareEqualSets() {
+        LWWElementSet otherSet = new LWWElementSet();
+
+        Element element = new Element("key1", 1, bias);
+        set.add(element);
+        otherSet.add(element);
+
+        assertTrue(set.compare(otherSet));
+
+        otherSet.add(new Element("key2", 2, bias));
+        assertTrue(set.compare(otherSet));
+    }
+
+    @Test
+    void testCompareDifferentSets() {
+        LWWElementSet otherSet = new LWWElementSet();
+
+        Element element1 = new Element("key1", 1, bias);
+        Element element2 = new Element("key2", 2, bias);
+
+        set.add(element1);
+        otherSet.add(element2);
+
+        assertFalse(set.compare(otherSet));
+    }
+
+    @Test
+    void testMerge() {
+        LWWElementSet otherSet = new LWWElementSet();
+
+        Element element1 = new Element("key1", 1, bias);
+        Element element2 = new Element("key2", 2, bias);
+
+        set.add(element1);
+        otherSet.add(element2);
+
+        set.merge(otherSet);
+
+        assertTrue(set.lookup(element1));
+        assertTrue(set.lookup(element2));
+    }
+
+    @Test
+    void testCompareTimestampsEqualTimestamps() {
+        LWWElementSet lwwElementSet = new LWWElementSet();
+
+        Element e1 = new Element("key1", 10, Bias.REMOVALS);
+        Element e2 = new Element("key1", 10, Bias.REMOVALS);
+
+        assertTrue(lwwElementSet.compareTimestamps(e1, e2));
+
+        e1 = new Element("key1", 10, Bias.ADDS);
+        e2 = new Element("key1", 10, Bias.ADDS);
+
+        assertFalse(lwwElementSet.compareTimestamps(e1, e2));
+    }
+}