Handle better realm url input parsing

src/start/RealmScreen.js

@@ -7,6 +7,7 @@ import styles from '../common/styles';
 import { Screen, ErrorMsg, ZulipButton, Input } from '../common';
 import { getAuthBackends } from '../api';
 import config from '../config';
+import { fixRealmUrl } from '../utils/url';
 
 type Props = {
   realm: ?string,
@@ -36,8 +37,10 @@ class RealmScreen extends React.Component {
       realm = `https://${realm}`;
     }
 
+    realm = realm.replace(/\/$/, '');
+
     this.setState({
-      realm,
+      realm: fixRealmUrl(realm),
       progress: true,
       error: undefined,
     });

src/utils/__tests__/url-test.js

@@ -9,6 +9,7 @@ import {
   isSpecialLink,
   getNarrowFromLink,
   getMessageIdFromLink,
+  fixRealmUrl,
 } from '../url';
 
 describe('getFullUrl', () => {
@@ -294,3 +295,17 @@ describe('getMessageIdFromLink', () => {
     ).toBe(1);
   });
 });
+
+describe('fixRealmUrl', () => {
+  test('when a realm url is missing a protocol, prepend https', () => {
+    expect(fixRealmUrl('example.com')).toEqual('https://example.com');
+  });
+
+  test('when a realm url has a trailing "/" remove it', () => {
+    expect(fixRealmUrl('https://example.com/')).toEqual('https://example.com');
+  });
+
+  test('when input url is correct, do not change it', () => {
+    expect(fixRealmUrl('https://example.com')).toEqual('https://example.com');
+  });
+});

src/utils/url.js

@@ -75,3 +75,14 @@ const getResourceNoAuth = (uri: string) => ({
 
 export const getResource = (uri: string, auth: Auth) =>
   (isUrlOnRealm(uri, auth.realm) ? getResourceWithAuth(uri, auth) : getResourceNoAuth(uri));
+
+export const fixRealmUrl = (url: string) => {
+  // Automatically prepend 'https://' if the user does not enter a protocol
+  if (url.search(/\b(http|https):\/\//) === -1) {
+    url = `https://${url}`;
+  }
+
+  url = url.replace(/\/$/, '');
+
+  return url;
+};