split compose time into separate package, added tests for compose time

src/components/Timepicker.jsx

@@ -4,6 +4,7 @@ import debounce from 'lodash/debounce'
 import Radium, { StyleRoot } from 'radium'
 
 import parseTime from '../helpers/parse-time'
+import composeTime from '../helpers/compose-time'
 import ClockWrapper from './ClockWrapper'
 import Time from './Time'
 
@@ -43,17 +44,7 @@ export class Timepicker extends React.Component {
 
 	getTime(){
 		const state = this.state;
-		const meridiemAdd = state.meridiem === 'pm' ? 12 : 0
-		const paddedMinute = ('0' + state.minute).slice(-2)
-		return {
-			formatted: `${state.hour}:${paddedMinute} ${state.meridiem}`,
-			formattedSimple: `${state.hour}:${paddedMinute}`,
-			formatted24: `${state.hour + meridiemAdd}:${paddedMinute}`,
-			hour: state.hour,
-			hour24: state.hour + meridiemAdd,
-			minute: state.minute,
-			meridiem: state.meridiem
-		}
+		return composeTime(state.hour, state.minute, state.meridiem);
 	}
 
 	handleTimeChange(unit, val, canChangeUnit){

src/helpers/__tests__/compose-time.js

@@ -0,0 +1,9 @@
+import compose from '../compose-time';
+
+describe('helpers/compose-time', () => {
+	test('formatted24', () => {
+		expect( compose(1, 30, 'am') ).toHaveProperty('formatted24', '1:30')
+		expect( compose(1, 30, 'pm') ).toHaveProperty('formatted24', '13:30')
+		expect( compose(12, 30, 'am') ).toHaveProperty('formatted24', '0:30')
+	})
+});

src/helpers/compose-time.js

@@ -0,0 +1,21 @@
+
+export default function composeTime(hour, minute, meridiem){
+	const paddedMinute = ('0' + minute).slice(-2)
+
+	let hour24 = hour;
+	if (meridiem === 'pm'){
+		hour24 = hour + 12;
+	} else if (meridiem === 'am' && hour === 12){
+		hour24 = 0;
+	}
+
+	return {
+		formatted: `${hour}:${paddedMinute} ${meridiem}`,
+		formattedSimple: `${hour}:${paddedMinute}`,
+		formatted24: `${hour24}:${paddedMinute}`,
+		hour: hour,
+		hour24: hour24,
+		minute: minute,
+		meridiem: meridiem
+	}
+}