merge: Add FibonacciNumber.js test case and update the decription of function. (TheAlgorithms#840)

Author: Yatin-kathuria

Dynamic-Programming/FibonacciNumber.js

@@ -1,5 +1,10 @@
-//  https://en.wikipedia.org/wiki/Fibonacci_number
-
+/**
+ * @function Fibonacci
+ * @description Fibonacci is the sum of previous two fibonacci numbers.
+ * @param {Integer} N - The input integer
+ * @return {Integer} fibonacci of N.
+ * @see [Fibonacci_Numbers](https://en.wikipedia.org/wiki/Fibonacci_number)
+ */
 const fibonacci = (N) => {
   // creating array to store values
   const memo = new Array(N + 1)

Dynamic-Programming/tests/FibonacciNumber.test.js

@@ -0,0 +1,19 @@
+import { fibonacci } from '../FibonacciNumber'
+
+describe('FibonacciNumber', () => {
+  it('fibonacci of 0', () => {
+    expect(fibonacci(0)).toBe(0)
+  })
+
+  it('fibonacci of 1', () => {
+    expect(fibonacci(1)).toBe(1)
+  })
+
+  it('fibonacci of 10', () => {
+    expect(fibonacci(10)).toBe(55)
+  })
+
+  it('fibonacci of 25', () => {
+    expect(fibonacci(25)).toBe(75025)
+  })
+})