Address feedback

Author: devversion

tools/gulp/tasks/payload.ts

@@ -2,8 +2,8 @@ import {task} from 'gulp';
 import {join} from 'path';
 import {statSync} from 'fs';
 import {isTravisBuild, isTravisMasterBuild} from '../util/travis-ci';
-import {openFirebaseDashboardApp} from '../util/firebase';
 import {buildConfig} from '../packaging/build-config';
+import {openFirebaseDashboardApp, openFirebaseDashboardAppAsGuest} from '../util/firebase';
 
 // These imports lack of type definitions.
 const request = require('request');
@@ -33,7 +33,9 @@ task('payload', ['material:clean-build'], async () => {
 
   if (isTravisBuild()) {
     // Open a connection to Firebase. For PRs the connection will be established as a guest.
-    const firebaseApp = openFirebaseDashboardApp(!isTravisMasterBuild());
+    const firebaseApp = isTravisMasterBuild() ?
+        openFirebaseDashboardApp() :
+        openFirebaseDashboardAppAsGuest();
     const database = firebaseApp.database();
     const currentSha = process.env['TRAVIS_PULL_REQUEST_SHA'] || process.env['TRAVIS_COMMIT'];
 
@@ -75,6 +77,12 @@ async function calculatePayloadDiff(database: any, currentSha: string, currentPa
 
   const previousPayload = await getLastPayloadResults(database);
 
+  if (!previousPayload) {
+    console.warn('There are no previous payload results uploaded. Cannot calculate payload ' +
+      'difference for this job');
+    return;
+  }
+
   // Calculate library sizes by combining the CDK and Material FESM 2015 bundles.
   const previousSize = previousPayload.cdk_fesm_2015 + previousPayload.material_fesm_2015;
   const currentSize = currentPayload.cdk_fesm_2015 + currentPayload.material_fesm_2015;
@@ -126,7 +134,9 @@ async function getLastPayloadResults(database: admin.database.Database) {
     .limitToLast(1)
     .once('value');
 
-  // The value of the DataSnapshot is an object with the SHA as a key. Only return the
-  // value of the object because the SHA is not necessary.
-  return snapshot.val()[Object.keys(snapshot.val())[0]];
+  // The value of the DataSnapshot is an object with the SHA as a key. Later only the
+  // first value of the object will be returned because the SHA is unnecessary.
+  const results = snapshot.val();
+
+  return snapshot.hasChildren() ? results[Object.keys(results)[0]] : null;
 }

tools/gulp/util/firebase.ts

@@ -5,20 +5,15 @@ const cloudStorage = require('@google-cloud/storage');
 // Firebase configuration for the Screenshot project. Use the config from the screenshot functions.
 const screenshotFirebaseConfig = require('../../screenshot-test/functions/config.json');
 
-/** Opens a connection to the Firebase dashboard app. */
-export function openFirebaseDashboardApp(asGuest = false) {
-  const databaseURL = 'https://material2-board.firebaseio.com';
-
-  // In some situations the service account credentials are not available and authorizing as
-  // a guest works fine. For example in Pull Requests the payload task just wants to read data.
-  if (asGuest) {
-    return firebase.initializeApp({ databaseURL });
-  }
+/** Database URL of the dashboard firebase project.*/
+const dashboardDatabaseUrl = 'https://material2-board.firebaseio.com';
 
+/** Opens a connection to the Firebase dashboard app using a service account. */
+export function openFirebaseDashboardApp(asGuest = false) {
   // Initialize the Firebase application with firebaseAdmin credentials.
   // Credentials need to be for a Service Account, which can be created in the Firebase console.
   return firebaseAdmin.initializeApp({
-    databaseURL,
+    databaseURL: dashboardDatabaseUrl,
     credential: firebaseAdmin.credential.cert({
       project_id: 'material2-board',
       client_email: '[email protected]',
@@ -29,6 +24,11 @@ export function openFirebaseDashboardApp(asGuest = false) {
   });
 }
 
+/** Opens a connection to the Firebase dashboard app with no authentication. */
+export function openFirebaseDashboardAppAsGuest() {
+  return firebase.initializeApp({ databaseURL: dashboardDatabaseUrl });
+}
+
 /**
  * Open Google Cloud Storage for screenshots.
  * The files uploaded to google cloud are also available to firebase storage.