Add Hash Table with Cuckoo Hashing (#3191)

src/test/java/com/thealgorithms/datastructures/hashmap/HashMapCuckooHashingTest.java

@@ -0,0 +1,104 @@
+package com.thealgorithms.datastructures.hashmap;
+
+import com.thealgorithms.datastructures.hashmap.hashing.HashMapCuckooHashing;
+import org.junit.jupiter.api.Test;
+
+import java.util.*;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class HashMapCuckooHashingTest {
+
+    @Test
+    void insertKey() {
+        HashMapCuckooHashing hashTable = new HashMapCuckooHashing(10);
+        assertEquals(0, hashTable.getNumberOfKeysInTable());
+
+        hashTable.insertKey2HashTable(3);
+
+        assertEquals(1, hashTable.getNumberOfKeysInTable());
+    }
+
+    @Test
+    void getKeyIndex() {
+        HashMapCuckooHashing hashTable = new HashMapCuckooHashing(10);
+        hashTable.insertKey2HashTable(8);
+        hashTable.insertKey2HashTable(4);
+
+        assertNotEquals(-1, hashTable.findKeyInTable(8));
+    }
+
+    @Test
+    void containsKey() {
+        HashMapCuckooHashing hashTable = new HashMapCuckooHashing(10);
+        hashTable.insertKey2HashTable(8);
+        boolean contains = hashTable.checkTableContainsKey(8);
+
+        assertTrue(contains);
+    }
+
+    @Test
+    void removeKey() {
+        HashMapCuckooHashing hashTable = new HashMapCuckooHashing(10);
+        hashTable.insertKey2HashTable(3);
+
+        int initialSize = hashTable.getNumberOfKeysInTable();
+
+        hashTable.deleteKeyFromHashTable(3);
+
+        assertEquals(initialSize - 1, hashTable.getNumberOfKeysInTable());
+    }
+
+    @Test
+    void removeNone() {
+        HashMapCuckooHashing hashTable = new HashMapCuckooHashing(10);
+        int initialSize = hashTable.getNumberOfKeysInTable();
+        try {
+            hashTable.deleteKeyFromHashTable(3);
+        }
+        catch (Exception e){
+            assertTrue(true);
+            return;
+        }
+        fail();
+    }
+
+    @Test
+    void reHashTableIncreasesTableSize() {
+        HashMapCuckooHashing hashTable = new HashMapCuckooHashing(10);
+        int initialSize = hashTable.getNumberOfKeysInTable();
+
+        hashTable.reHashTableIncreasesTableSize();
+
+        assertEquals(initialSize * 2, hashTable.getNumberOfKeysInTable());
+    }
+
+    @Test
+    void hashFunctionsAreDifferent() {
+        HashMapCuckooHashing hashTable = new HashMapCuckooHashing(10);
+        hashTable.insertKey2HashTable(33);
+
+        assertNotEquals(hashTable.hashFunction1(3), hashTable.hashFunction2(3));
+    }
+
+    @Test
+    void avoidInfiniteLoops() {
+        HashMapCuckooHashing hashTable = new HashMapCuckooHashing(10);
+        hashTable.insertKey2HashTable(0);
+        hashTable.insertKey2HashTable(10);
+        hashTable.insertKey2HashTable(100);
+
+        assertTrue(hashTable.checkTableContainsKey(0));
+        assertTrue(hashTable.checkTableContainsKey(10));
+        assertTrue(hashTable.checkTableContainsKey(100));
+    }
+
+
+    private HashMapCuckooHashing createHashMapCuckooHashing() {
+        HashMapCuckooHashing hashTable = new HashMapCuckooHashing(10);
+        int[] values = {11, 22, 33, 44, 55, 66, 77, 88, 99, 111, 222};
+        Arrays.stream(values).forEach(hashTable::insertKey2HashTable);
+        return hashTable;
+    }
+
+}