feat(): add new method random on num class (#25)

Author: houssenedao

.github/PULL_REQUEST_TEMPLATE.md

@@ -24,7 +24,7 @@ What kind of change does this PR introduce?
 
 <!-- Please describe the current behavior that you are modifying, or link to a relevant issue. -->
 
-Issue Number: N/A
+Issue Num: N/A
 
 ## What is the new behavior?
 

lib/exceptions/index.ts

@@ -1 +1,2 @@
 export * from './str.exception';
+export * from './num.exception';

lib/exceptions/num.exception.ts

@@ -0,0 +1,11 @@
+export class NumException extends Error {
+  name: 'NumException';
+
+  /**
+   * @constructor
+   * @param {string} message
+   */
+  constructor(message: string) {
+    super(message);
+  }
+}

lib/num/num.interface.ts

@@ -0,0 +1,3 @@
+export interface INumber {
+  random(min: number, max: number): number;
+}

lib/num/num.spec.ts

@@ -0,0 +1,35 @@
+import { Num } from './num';
+import { NumException } from '../exceptions';
+
+describe('Number', () => {
+  let number: Num;
+
+  beforeEach(async () => {
+    number = new Num();
+  });
+
+  it('should be defined', () => {
+    expect(number).toBeDefined();
+  });
+
+  describe('Random method', () => {
+    it('should have method random', () => {
+      expect(number).toHaveProperty('random');
+    });
+
+    it('Use random method', () => {
+      expect(number.random(5)).not.toBeNull();
+      expect(number.random(5)).not.toBeNaN();
+      expect(number.random(5)).toBeGreaterThanOrEqual(0);
+      expect(number.random(5)).toBeLessThanOrEqual(5);
+    });
+
+    it('should have method random and return value', () => {
+      number.random = jest.fn().mockReturnValue(5);
+
+      expect(number.random(5)).not.toBeNull();
+      expect(number.random(5)).not.toBeNaN();
+      expect(number.random(5)).toEqual(5);
+    });
+  });
+});

lib/num/num.ts

@@ -0,0 +1,16 @@
+import { INumber } from './num.interface';
+
+export class Num implements INumber {
+  /**
+   * Random a number.
+   * @param min
+   * @param max
+   */
+  random(min: number, max?: number): number {
+    if (max) {
+      return Math.floor(Math.random() * (max - min)) + min;
+    }
+
+    return Math.floor(Math.random() * (min + 1));
+  }
+}