Add tests for Tree Sort (#3787)

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

@@ -0,0 +1,88 @@
+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 TreeSort
+ */
+
+public class TreeSortTest {
+    private TreeSort treeSort = new TreeSort();
+
+    @Test 
+    public void treeSortEmptyArray(){
+        Integer[] inputArray = {};
+        Integer[] outputArray = treeSort.sort(inputArray);
+        Integer[] expectedOutput = {};
+        assertArrayEquals(outputArray, expectedOutput);
+    }
+
+    @Test
+    public void treeSortSingleStringElement() {
+        String[] inputArray = {"Test"};
+        String[] outputArray = treeSort.sort(inputArray);
+        String[] expectedArray = {"Test"};
+        assertArrayEquals(outputArray, expectedArray);
+    }
+
+    @Test
+    public void treeSortStringArray() {
+        String[] inputArray = {
+            "F6w9",
+            "l1qz",
+            "dIxH",
+            "larj",
+            "kRzy",
+            "vnNH",
+            "3ftM",
+            "hc4n",
+            "C5Qi",
+            "btGF"
+        };
+        String[] outputArray = treeSort.sort(inputArray);
+        String[] expectedArray = {
+            "3ftM",
+            "C5Qi",
+            "F6w9",
+            "btGF",
+            "dIxH",
+            "hc4n",
+            "kRzy",
+            "l1qz",
+            "larj",
+            "vnNH"
+        };
+        assertArrayEquals(outputArray, expectedArray);
+    }
+
+    @Test 
+    public void treeSortIntegerArray() {
+        Integer[] inputArray = { -97, -44, -4, -85, -92, 74, 79, -26, 76, -5 };
+        Integer[] outputArray = treeSort.sort(inputArray);
+        Integer[] expectedArray = { -97, -92, -85, -44, -26, -5, -4, 74, 76, 79 };
+        assertArrayEquals(outputArray, expectedArray);
+    }
+
+    @Test
+    public void treeSortDoubleArray() {
+        Double[] inputArray = {
+            0.8047485045,  0.4493112337,
+            0.8298433723,  0.2691406748,
+            0.2482782839,  0.5976243420,
+            0.6746235284,  0.0552623569,
+            0.3515624123,  0.0536747336
+        };
+        Double[] outputArray = treeSort.sort(inputArray);
+        Double[] expectedArray = {
+            0.0536747336,  0.0552623569,
+            0.2482782839,  0.2691406748,
+            0.3515624123,  0.4493112337,
+            0.5976243420,  0.6746235284, 
+            0.8047485045,  0.8298433723
+        };
+        assertArrayEquals(outputArray, expectedArray);
+    }
+}