Added test cases to CocktailShakerSort. (TheAlgorithms#3766)

* Add testcase to CocktailShakerSort Algorithm

* fixed method name to lowerCamelCase

Author: Tabbygray

src/test/java/com/thealgorithms/sorts/CocktailShakerSortTest.java

@@ -0,0 +1,68 @@
+package com.thealgorithms.sorts;
+
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+
+import org.junit.jupiter.api.Test;
+
+/**
+ * @author Tabbygray (https://github.com/Tabbygray)
+ * @see CocktailShakerSort
+ */
+public class CocktailShakerSortTest {
+    
+    private CocktailShakerSort cocktailShakerSort = new CocktailShakerSort();
+
+    @Test
+    public void cocktailShakerSortEmptyArray(){
+        Integer[] inputArray = {};
+        Integer[] outputArray = cocktailShakerSort.sort(inputArray);
+        Integer[] expectedOutput = {};
+        assertArrayEquals(outputArray, expectedOutput);
+    }
+
+    @Test
+    public void cocktailShakerSortSingleStringElementArray(){
+        String[] inputArray = {"Test"};
+        String[] outputArray = cocktailShakerSort.sort(inputArray);
+        String[] expectedOutput = {"Test"};
+        assertArrayEquals(outputArray, expectedOutput);
+    }
+
+    @Test
+    public void cocktailShakerSortIntegerArray(){
+        Integer[] inputArray = { 2, 92, 1, 33, -33, 27, 5, 100, 78, 99, -100};
+        Integer[] outputArray = cocktailShakerSort.sort(inputArray);
+        Integer[] expectedOutput = { -100, -33, 1, 2, 5, 27, 33, 78, 92, 99, 100};
+        assertArrayEquals(outputArray, expectedOutput);
+    }
+
+    @Test
+    public void cocktailShakerSortStringArray(){
+        String[] inputArray = {
+            "g3x1",
+            "dN62",
+            "oMdr",
+            "KL2b",
+            "JddJ",
+            "mvE8",
+            "Ej7Q",
+            "n7n7",
+            "LGTg",
+            "2E1w",
+        };
+        String[] outputArray = cocktailShakerSort.sort(inputArray);
+        String[] expectedOutput = {
+            "2E1w",
+            "Ej7Q",
+            "JddJ",
+            "KL2b",
+            "LGTg",
+            "dN62",
+            "g3x1",
+            "mvE8",
+            "n7n7",
+            "oMdr",
+        };
+        assertArrayEquals(outputArray, expectedOutput);
+    }
+}