Closes #3274 Add BubbleSort unit tests

src/main/java/com/thealgorithms/sorts/BubbleSort.java

@@ -32,28 +32,4 @@ public <T extends Comparable<T>> T[] sort(T[] array) {
         }
         return array;
     }
-
-    /**
-     * Driver Code
-     */
-    public static void main(String[] args) {
-
-        Integer[] integers = {4, 23, 6, 78, 1, 54, 231, 9, 12};
-        BubbleSort bubbleSort = new BubbleSort();
-        bubbleSort.sort(integers);
-
-        for (int i = 0; i < integers.length - 1; ++i) {
-            assert integers[i] <= integers[i + 1];
-        }
-        print(integers);
-        /* output: [1, 4, 6, 9, 12, 23, 54, 78, 231] */
-
-        String[] strings = {"c", "a", "e", "b", "d"};
-        bubbleSort.sort(strings);
-        for (int i = 0; i < strings.length - 1; i++) {
-            assert strings[i].compareTo(strings[i + 1]) <= 0;
-        }
-        print(bubbleSort.sort(strings));
-        /* output: [a, b, c, d, e] */
-    }
 }

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

@@ -0,0 +1,53 @@
+package com.thealgorithms.sorts;
+
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+
+import org.junit.jupiter.api.Test;
+
+/**
+ * @author Aitor Fidalgo (https://github.com/aitorfi)
+ * @see BubbleSort
+ */
+public class BubbleSortTest {
+    private BubbleSort bubbleSort = new BubbleSort();
+
+    @Test
+    public void bubbleSortEmptyArray() {
+        Integer[] inputArray = {};
+        Integer[] outputArray = bubbleSort.sort(inputArray);
+        Integer[] expectedOutput = {};
+        assertArrayEquals(outputArray, expectedOutput);
+    }
+
+    @Test
+    public void bubbleSortSingleIntegerElementArray() {
+        Integer[] inputArray = {4};
+        Integer[] outputArray = bubbleSort.sort(inputArray);
+        Integer[] expectedOutput = {4};
+        assertArrayEquals(outputArray, expectedOutput);
+    }
+
+    @Test
+    public void bubbleSortSingleStringElementArray() {
+        String[] inputArray = {"s"};
+        String[] outputArray = bubbleSort.sort(inputArray);
+        String[] expectedOutput = {"s"};
+        assertArrayEquals(outputArray, expectedOutput);
+    }
+
+    @Test
+    public void bubbleSortIntegerArray() {
+        Integer[] inputArray = {4, 23, -6, 78, 1, 54, 23, -6, -231, 9, 12};
+        Integer[] outputArray = bubbleSort.sort(inputArray);
+        Integer[] expectedOutput = {-231, -6, -6, 1, 4, 9, 12, 23, 23, 54, 78};
+        assertArrayEquals(outputArray, expectedOutput);
+    }
+
+    @Test
+    public void bubbleSortStringArray() {
+        String[] inputArray = {"cbf", "auk", "ó", "(b", "a", ")", "au", "á", "cba", "auk", "(a", "bhy", "cba"};
+        String[] outputArray = bubbleSort.sort(inputArray);
+        String[] expectedOutput = {"(a", "(b", ")", "a", "au", "auk", "auk", "bhy", "cba", "cba", "cbf", "á", "ó"};
+        assertArrayEquals(outputArray, expectedOutput);
+    }
+}