navReducer: Transplant away LOGIN_SUCCESS logic.

Soon, we'll dismantle `navReducer`, as its purpose is incompatible
with a design where we manage navigation state separately from our
Redux-stored data (#3804).

So, convert the `navReducer`'s `LOGIN_SUCCESS` case into
instructions to navigate to the loading screen at the dispatch
sites.

Author: chrisbobbe

src/nav/__tests__/navReducer-test.js

@@ -1,32 +1,9 @@
 import deepFreeze from 'deep-freeze';
 
-import { LOGIN_SUCCESS, INITIAL_FETCH_COMPLETE } from '../../actionConstants';
+import { INITIAL_FETCH_COMPLETE } from '../../actionConstants';
 import navReducer, { getStateForRoute } from '../navReducer';
 
 describe('navReducer', () => {
-  describe('LOGIN_SUCCESS', () => {
-    test('replaces the existing route stack with "loading" on sign in', () => {
-      const prevState = deepFreeze({
-        index: 2,
-        routes: [{ key: 'one' }, { key: 'two' }, { key: 'password' }],
-      });
-
-      const action = deepFreeze({
-        type: LOGIN_SUCCESS,
-      });
-
-      const expectedState = {
-        index: 0,
-        routes: [{ routeName: 'loading' }],
-      };
-
-      const newState = navReducer(prevState, action);
-
-      expect(newState.index).toEqual(expectedState.index);
-      expect(newState.routes[0].routeName).toEqual(expectedState.routes[0].routeName);
-    });
-  });
-
   describe('INITIAL_FETCH_COMPLETE', () => {
     test('do not mutate navigation state if already at the same route', () => {
       const prevState = getStateForRoute('main');

src/nav/navReducer.js

@@ -3,7 +3,7 @@ import type { NavigationAction } from 'react-navigation';
 
 import type { NavigationState, Action } from '../types';
 import AppNavigator from './AppNavigator';
-import { INITIAL_FETCH_COMPLETE, LOGIN_SUCCESS } from '../actionConstants';
+import { INITIAL_FETCH_COMPLETE } from '../actionConstants';
 
 /**
  * Get the initial state for the given route.
@@ -28,9 +28,6 @@ export const initialState = getStateForRoute('loading');
 
 export default (state: NavigationState = initialState, action: Action): NavigationState => {
   switch (action.type) {
-    case LOGIN_SUCCESS:
-      return getStateForRoute('loading');
-
     case INITIAL_FETCH_COMPLETE:
       return state.routes[0].routeName === 'main' ? state : getStateForRoute('main');
 

src/start/AuthScreen.js

@@ -29,7 +29,7 @@ import { getCurrentRealm } from '../selectors';
 import RealmInfo from './RealmInfo';
 import { encodeParamsForUrl } from '../utils/url';
 import * as webAuth from './webAuth';
-import { loginSuccess, navigateToDev, navigateToPassword } from '../actions';
+import { loginSuccess, navigateToDev, navigateToPassword, resetToLoading } from '../actions';
 import IosCompliantAppleAuthButton from './IosCompliantAppleAuthButton';
 import openLink from '../utils/openLink';
 
@@ -234,6 +234,7 @@ class AuthScreen extends PureComponent<Props> {
     const { dispatch, realm } = this.props;
     const auth = webAuth.authFromCallbackUrl(event.url, otp, realm);
     if (auth) {
+      dispatch(resetToLoading());
       dispatch(loginSuccess(auth.realm, auth.email, auth.apiKey));
     }
   };