Add tests for power using recursion algorithm (#4335)

src/test/java/com/thealgorithms/maths/PowerUsingRecursionTest.java

@@ -0,0 +1,20 @@
+package com.thealgorithms.maths;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import org.junit.jupiter.api.Test;
+
+/**
+ * Test case for Power using Recursion
+ * @author Bama Charan Chhandogi (https://github.com/BamaCharanChhandogi)
+ */
+
+class PowerUsingRecursionTest {
+
+    @Test
+    void testPowerUsingRecursion() {
+        assertEquals(32.0, PowerUsingRecursion.power(2.0, 5));
+        assertEquals(97.65625, PowerUsingRecursion.power(2.5, 5));
+        assertEquals(81, PowerUsingRecursion.power(3, 4));
+    }
+}