diff --git a/bridge/e2e/auth/auth.e2e.js b/bridge/e2e/auth/auth.e2e.js
index 9950791a..c3549ec6 100644
--- a/bridge/e2e/auth/auth.e2e.js
+++ b/bridge/e2e/auth/auth.e2e.js
@@ -1,4 +1,26 @@
 describe('auth()', () => {
+  beforeEach(async () => {
+    if (firebase.auth().currentUser) await firebase.auth().signOut();
+  });
+
+  describe('signInWithCustomToken()', () => {
+    it('signs in with a admin sdk created custom auth token', async () => {
+      const customUID = `custom${randomString(12, '#aA')}`;
+      const token = await firebaseAdmin.auth().createCustomToken(customUID);
+      const user = await firebase.auth().signInWithCustomToken(token);
+      user.uid.should.equal(customUID);
+      firebase.auth().currentUser.uid.should.equal(customUID);
+
+      await firebase.auth().signOut();
+      const {
+        user: user2,
+      } = await firebase.auth().signInAndRetrieveDataWithCustomToken(token);
+
+      user2.uid.should.equal(customUID);
+      firebase.auth().currentUser.uid.should.equal(customUID);
+    });
+  });
+
   describe('onAuthStateChanged()', () => {
     it('calls callback with the current user and when auth state changes', async () => {
       await firebase.auth().signInAnonymouslyAndRetrieveData();
diff --git a/bridge/e2e/init.js b/bridge/e2e/init.js
index f4684061..bf1be32c 100755
--- a/bridge/e2e/init.js
+++ b/bridge/e2e/init.js
@@ -1,9 +1,6 @@
 const detox = require('detox');
 const config = require('../package.json').detox;
-
-global.sinon = require('sinon');
-require('should-sinon');
-global.should = require('should');
+require('./../helpers');
 
 before(async () => {
   await detox.init(config);
@@ -12,27 +9,3 @@ before(async () => {
 after(async () => {
   await detox.cleanup();
 });
-
-Object.defineProperty(global, 'firebase', {
-  get() {
-    return bridge.module;
-  },
-});
-
-global.sleep = duration =>
-  new Promise(resolve => {
-    setTimeout(resolve, duration);
-  });
-
-global.randomString = (length, chars) => {
-  let mask = '';
-  if (chars.indexOf('a') > -1) mask += 'abcdefghijklmnopqrstuvwxyz';
-  if (chars.indexOf('A') > -1) mask += 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';
-  if (chars.indexOf('#') > -1) mask += '0123456789';
-  if (chars.indexOf('!') > -1) mask += '~`!@#$%^&*()_+-={}[]:";\'<>?,./|\\';
-  let result = '';
-  for (let i = length; i > 0; --i) {
-    result += mask[Math.round(Math.random() * (mask.length - 1))];
-  }
-  return result;
-};