BAEL-3519 (#8169)

* BAEL-3519
- Fibonacci Series
- Recursive method
- Iterative method

* - Added new method that uses Golden Ratio to calculate the given term of Fibonacci Series

* added binet formula implementation of constant time for fibonacci term

java-numbers-2/src/test/java/com/baeldung/fibonacci/FibonacciSeriesUtilsUnitTest.java

@@ -0,0 +1,29 @@
+package com.baeldung.fibonacci;
+
+import static org.junit.Assert.assertEquals;
+
+import org.junit.Test;
+
+public class FibonacciSeriesUtilsUnitTest {
+
+    @Test
+    public void givenTermToCalculate_thenReturnThatTermUsingRecursion() {
+        int term = 10;
+        int expectedValue = 55;
+        assertEquals(FibonacciSeriesUtils.nthFibonacciTermRecursiveMethod(term), expectedValue);
+    }
+
+    @Test
+    public void givenTermToCalculate_thenReturnThatTermUsingIteration() {
+        int term = 10;
+        int expectedValue = 55;
+        assertEquals(FibonacciSeriesUtils.nthFibonacciTermIterativeMethod(term), expectedValue);
+    }
+
+    @Test
+    public void givenTermToCalculate_thenReturnThatTermUsingBinetsFormula() {
+        int term = 10;
+        int expectedValue = 55;
+        assertEquals(FibonacciSeriesUtils.nthFibonacciTermUsingBinetsFormula(term), expectedValue);
+    }
+}