common util selectItem signature update; common util test update

src/utils/common.js

@@ -39,6 +39,6 @@ export function indexEquals(withNumber) {
  * @param byCondition
  * @param map
  */
-export function selectItem(byCondition, map){
+export function selectItem(byCondition, map = i => i) {
     return (result, item) => byCondition(item) ? map(item): map(result)
 }

test/utils/common.js

@@ -4,14 +4,14 @@ import {selectItem}  from '../../src/utils/common';
 describe('utils', () => {
     describe('common.js', () => {
         describe('selectItem', () => {
-            let sample = [[1235, 'hello'], [2352, 'banana']];
-
             it('should return a function', () => {
                 let fn = selectItem();
                 fn.should.be.type('function');
             });
 
             it('should accept a function as a first parameter and use it as byCondition', () => {
+                let sample = [[1235, 'hello'], [2352, 'banana']];
+
                 let fn = selectItem(
                     i => i[0] === 2352 && i[1] === 'banana' && i.length === 2,
                     i => i[1]
@@ -22,6 +22,8 @@ describe('utils', () => {
             });
 
             it('should accept a function as a second parameter and use it as mapping function', () => {
+                let sample = [[1235, 'hello'], [2352, 'banana']];
+
                 let fn = selectItem(
                     i => i[0] === 2352,
                     i => i[1]
@@ -30,6 +32,20 @@ describe('utils', () => {
                 let result = sample.reduce(fn);
                 result.should.be.equal('banana');
             });
+
+            it('should pass with one parameter', () => {
+                let sample = ['hello', 'lol', 'banana'];
+
+                let result = sample.reduce(selectItem(i => i === 'banana'));
+                result.should.be.equal('banana');
+            });
+
+            it('should get a null in reduce result if reduce calls with second parameter that is null', () => {
+                let sample = ['hello', 'lol', 'banana'];
+
+                let result = sample.reduce(selectItem(i => i === 'apple'), null);
+                should.not.exist(result);
+            });
         });
     });
 });