Use nothing-changed helper in home to prevent unnecessary render

components/home.js

@@ -11,6 +11,7 @@ import { getOrCreateCycleDay, getCycleDaysSortedByDate } from '../db'
 import { getFertilityStatusForDay } from '../lib/sympto-adapter'
 import styles from '../styles'
 import AppText, { AppTextLight } from './app-text'
+import nothingChanged from '../helpers/db-unchanged'
 
 export default class Home extends Component {
   constructor(props) {
@@ -32,7 +33,8 @@ export default class Home extends Component {
     this.cycleDays.addListener(this.updateState)
   }
 
-  updateState = () => {
+  updateState = (_, changes) => {
+    if (nothingChanged(changes)) return
     const prediction = this.getBleedingPrediction()
     const fertilityStatus = getFertilityStatusForDay(this.todayDateString)
     this.setState({

helpers/db-unchanged.js

@@ -0,0 +1,3 @@
+export default function (dbChanges) {
+  return Object.values(dbChanges).every(changeArray => changeArray.length === 0)
+}

lib/notifications.js

@@ -5,6 +5,7 @@ import Moment from 'moment'
 import { settings as labels } from '../components/labels'
 import { getOrCreateCycleDay, getBleedingDaysSortedByDate } from '../db'
 import cycleModule from './cycle'
+import nothingChanged from '../helpers/db-unchanged'
 
 export default function setupNotifications(navigate) {
   Notification.configure({
@@ -80,7 +81,3 @@ function setupPeriodReminder() {
     }
   }
 }
-
-function nothingChanged(dbChanges) {
-  return Object.values(dbChanges).every(changeArray => changeArray.length === 0)
-}