refactor: ReverseStackUsingRecursion (#5386)

src/test/java/com/thealgorithms/others/ReverseStackUsingRecursionTest.java

@@ -0,0 +1,58 @@
+package com.thealgorithms.others;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.util.Stack;
+import org.junit.jupiter.api.Test;
+
+public class ReverseStackUsingRecursionTest {
+
+    @Test
+    void testReverseWithMultipleElements() {
+        Stack<Integer> stack = new Stack<>();
+        for (int i = 0; i < 5; i++) {
+            stack.push(i);
+        }
+
+        ReverseStackUsingRecursion.reverse(stack);
+
+        for (int i = 0; i < 5; i++) {
+            assertEquals(i, stack.pop());
+        }
+        assertTrue(stack.isEmpty());
+    }
+
+    @Test
+    void testReverseWithSingleElement() {
+        Stack<Integer> stack = new Stack<>();
+        stack.push(1);
+
+        ReverseStackUsingRecursion.reverse(stack);
+
+        assertEquals(1, stack.pop());
+        assertTrue(stack.isEmpty());
+    }
+
+    @Test
+    void testReverseWithEmptyStack() {
+        Stack<Integer> stack = new Stack<>();
+
+        ReverseStackUsingRecursion.reverse(stack);
+
+        assertTrue(stack.isEmpty());
+    }
+
+    @Test
+    void testReverseWithNullStack() {
+        Stack<Integer> stack = null;
+
+        Exception exception = assertThrows(IllegalArgumentException.class, () -> ReverseStackUsingRecursion.reverse(stack));
+
+        String expectedMessage = "Stack cannot be null";
+        String actualMessage = exception.getMessage();
+
+        assertTrue(actualMessage.contains(expectedMessage));
+    }
+}