Merge pull request #9 from kentcdodds/pr/padLeft

WIP: Cannot get coverage quite there

src/index.js

@@ -1,9 +1,13 @@
 import flatten from './flatten'
 import getQueryStringParam from './get-query-string-param'
 import snakeToCamel from './snake-to-camel'
+import padLeft from './pad-left'
+
 
 export {
   flatten,
   snakeToCamel,
   getQueryStringParam,
+  padLeft,
 }
+

src/pad-left.js

@@ -0,0 +1,21 @@
+export default padLeft
+
+/**
+ * Original Source: http://stackoverflow.com/a/34083277/971592
+ *
+ * This method will pad the left of the given string by
+ * the given size with the given character
+ *
+ * @param {String} str - The string to pad
+ * @param {Number} size - The total size to pad
+ * @param {String} padWith - The character to use for padding
+ * @return {String} - The padded string
+ */
+function padLeft(str, size, padWith) {
+  if (size <= str.length) {
+    return str
+  } else {
+    return Array(size - str.length + 1).join(padWith || '0') + str
+  }
+}
+

test/pad-left.test.js

@@ -0,0 +1,28 @@
+import test from 'ava'
+import {padLeft} from '../src'
+
+test('pads left of the given string', t => {
+  const original = '123'
+  const expected = 'zz123'
+  const padLength = 5
+  const padWith = 'z'
+  const actual = padLeft(original, padLength, padWith)
+  t.same(actual, expected)
+})
+
+test('defaults to pad a zero', t => {
+  const original = '123'
+  const expected = '00123'
+  const padLength = 5
+  const actual = padLeft(original, padLength)
+  t.same(actual, expected)
+})
+
+test('does not pad a string longer than the pad length', t => {
+  const original = '1234'
+  const expected = '1234'
+  const padLength = 3
+  const actual = padLeft(original, padLength)
+  t.same(actual, expected)
+})
+