Merge pull request #717 from Chalarangelo/longest-item-patch

Updated longestItem + tests

snippets/longestItem.md

@@ -1,11 +1,13 @@
 ### longestItem
 
 Takes any number of iterable objects or objects with a `length` property and returns the longest one.
+If multiple objects have the same length, the first one will be returned.
+Returns `undefined` if no arguments are provided.
 
-Use `Array.reduce()` to collect the longest element.  Returns [] for empty array.
+Use `Array.reduce()`, comparing the `length` of objects to find the longest one.  
 
 ```js
-const longestItem = (...vals) => [...vals].reduce((a, x) => (a.length > x.length ? a : x), []);
+const longestItem = (val, ...vals) => [val, ...vals].reduce((a, x) => x.length > a.length ? x : a);
 ```
 
 ```js

test/longestItem/longestItem.js

@@ -1,2 +1,2 @@
-const longestItem = (...vals) => [...vals].reduce((a, x) => (a.length > x.length ? a : x), []);
+const longestItem = (val, ...vals) => [val, ...vals].reduce((a, x) => x.length > a.length ? x : a);
 module.exports = longestItem;

test/longestItem/longestItem.test.js

@@ -4,6 +4,29 @@ const longestItem = require('./longestItem.js');
 test('longestItem is a Function', () => {
   expect(longestItem).toBeInstanceOf(Function);
 });
-test('Returns the longest object', () => {
+test('Returns the longest object from plain values', () => {
   expect(longestItem('this', 'is', 'a', 'testcase')).toEqual('testcase');
 });
+test('Returns the longest object from a spread array', () => {
+  expect(longestItem(...['a', 'ab', 'abc'])).toEqual('abc');
+});
+test('Returns the longest object from mixed input', () => {
+  expect(longestItem(...['a', 'ab', 'abc'],'abcd')).toEqual('abcd');
+});
+test('Returns the longest array', () => {
+  expect(longestItem([1, 2, 3], [1, 2], [1, 2, 3, 4, 5])).toEqual([1, 2, 3, 4, 5]);
+});
+test('Returns the longest object when comparing arrays and strings', () => {
+  expect(longestItem([1, 2, 3], 'foobar')).toEqual('foobar');
+});
+test('Returns undefined without any input', () => {
+  expect(longestItem()).toEqual(undefined);
+});
+test('Returns first found of all similar', () => {
+  expect(longestItem('a','b','c')).toEqual('a');
+});
+test('Throws TypeError if all inputs are undefined', () => {
+  expect(() => {
+    longestItem(undefined,undefined);
+  }).toThrow(TypeError);
+});