Rename `navigationState.children` to `navigationState.routes`.

Summary:
[Experimental API breaking changes]

The notion of `parent` or `children` in navigaton is misleading. We have no intention to maintain or
build the nested or hierarchical navigation states. To be clear, rename `navigationState.children` to
`navigationState.route`.

Reviewed By: ericvicenti

Differential Revision: D3332115

fbshipit-source-id: c72ed08acaf030fb9c60abf22fb15cc0f44b3485

Examples/UIExplorer/NavigationExperimental/NavigationAnimatedExample.js

@@ -50,7 +50,7 @@ const ExampleReducer = NavigationReducer.StackReducer({
   initialState: {
     key: 'AnimatedExampleStackKey',
     index: 0,
-    children: [
+    routes: [
       {key: 'First Route'},
     ],
   },

Examples/UIExplorer/NavigationExperimental/NavigationBasicExample.js

@@ -43,7 +43,7 @@ const ExampleReducer = NavigationReducer.StackReducer({
   initialState: {
     key: 'BasicExampleStackKey',
     index: 0,
-    children: [
+    routes: [
       {key: 'First Route'},
     ],
   },
@@ -59,12 +59,12 @@ const NavigationBasicExample = React.createClass({
     return (
       <ScrollView style={styles.topView}>
         <NavigationExampleRow
-          text={`Current page: ${this.state.children[this.state.index].key}`}
+          text={`Current page: ${this.state.croutes[this.state.index].key}`}
         />
         <NavigationExampleRow
-          text={`Push page #${this.state.children.length}`}
+          text={`Push page #${this.state.routes.length}`}
           onPress={() => {
-            this._handleAction({ type: 'push', key: 'page #' + this.state.children.length });
+            this._handleAction({ type: 'push', key: 'page #' + this.state.routes.length });
           }}
         />
         <NavigationExampleRow

Examples/UIExplorer/NavigationExperimental/NavigationCardStackExample.js

@@ -57,7 +57,7 @@ function createReducer(initialState) {
 const ExampleReducer = createReducer({
   index: 0,
   key: 'exmaple',
-  children: [{key: 'First Route'}],
+  routes: [{key: 'First Route'}],
 });
 
 class NavigationCardStackExample extends React.Component {

Examples/UIExplorer/NavigationExperimental/NavigationCompositionExample.js

@@ -106,7 +106,7 @@ const ExampleAppReducer = NavigationReducer.TabsReducer({
       initialState: {
         key: 'notifs',
         index: 0,
-        children: [
+        routes: [
           {key: 'base', type: 'NotifsPage'},
         ],
       },
@@ -121,7 +121,7 @@ const ExampleAppReducer = NavigationReducer.TabsReducer({
       initialState: {
         key: 'settings',
         index: 0,
-        children: [
+        routes: [
           {key: 'base', type: 'SettingsPage'},
         ],
       },
@@ -136,7 +136,7 @@ const ExampleAppReducer = NavigationReducer.TabsReducer({
       initialState: {
         key: 'profile',
         index: 0,
-        children: [
+        routes: [
           {key: 'base', type: 'ProfilePage'},
         ],
       },
@@ -256,7 +256,7 @@ class NavigationCompositionExample extends React.Component {
           onNavigate={this.handleAction.bind(this)}
         />
         <NavigationExampleTabBar
-          tabs={this.state.children}
+          tabs={this.state.routes}
           index={this.state.index}
           onNavigate={this.handleAction.bind(this)}
         />
@@ -284,7 +284,7 @@ class ExampleMainView extends React.Component {
 
   _renderScene(): ReactElement {
     const {navigationState} = this.props;
-    const childState = navigationState.children[navigationState.index];
+    const childState = navigationState.routes[navigationState.index];
     return (
       <ExampleTabScreen
         key={'tab_screen' + childState.key}

Examples/UIExplorer/NavigationExperimental/NavigationTabsExample.js

@@ -78,13 +78,13 @@ class NavigationTabsExample extends React.Component {
     return (
       <View style={styles.topView}>
         <ExmpleTabPage
-          tabs={this.state.children}
+          tabs={this.state.routes}
           index={this.state.index}
           onExampleExit={this.props.onExampleExit}
           onNavigate={this.handleAction.bind(this)}
         />
         <NavigationExampleTabBar
-          tabs={this.state.children}
+          tabs={this.state.routes}
           index={this.state.index}
           onNavigate={this.handleAction.bind(this)}
         />

Examples/UIExplorer/UIExplorerNavigationReducer.js

@@ -1,4 +1,11 @@
 /**
+ * Copyright (c) 2013-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ *
  * The examples provided by Facebook are for non-commercial testing and
  * evaluation purposes only.
  *
@@ -39,7 +46,7 @@ export type UIExplorerNavigationState = {
 const UIExplorerStackReducer = StackReducer({
   getPushedReducerForAction: (action, lastState) => {
     if (action.type === 'UIExplorerExampleAction' && UIExplorerList.Modules[action.openExample]) {
-      if (lastState.children.find(child => child.key === action.openExample)) {
+      if (lastState.routes.find(route => route.key === action.openExample)) {
         // The example is already open, we should avoid pushing examples twice
         return null;
       }
@@ -51,7 +58,7 @@ const UIExplorerStackReducer = StackReducer({
   initialState: {
     key: 'UIExplorerMainStack',
     index: 0,
-    children: [
+    routes: [
       {key: 'AppList'},
     ],
   },
@@ -70,7 +77,7 @@ function UIExplorerNavigationReducer(lastState: ?UIExplorerNavigationState, acti
       stack: {
         key: 'UIExplorerMainStack',
         index: 0,
-        children: [
+        routes: [
           {
             key: 'AppList',
             filter: action.filter,

Libraries/NavigationExperimental/NavigationPropTypes.js

@@ -44,7 +44,7 @@ const navigationRoute = PropTypes.shape({
 const navigationState = PropTypes.shape({
   index: PropTypes.number.isRequired,
   key: PropTypes.string.isRequired,
-  children: PropTypes.arrayOf(navigationRoute),
+  routes: PropTypes.arrayOf(navigationRoute),
 });
 
 /* NavigationLayout */

Libraries/NavigationExperimental/NavigationStateUtils.js

@@ -18,34 +18,34 @@ import type {
   NavigationState,
 } from 'NavigationTypeDefinition';
 
-function getParent(state: NavigationRoute): ?NavigationState {
+function getParent(state: NavigationState): ?NavigationState {
   if (
     (state instanceof Object) &&
-    (state.children instanceof Array) &&
-    (state.children[0] !== undefined) &&
+    (state.routes instanceof Array) &&
+    (state.routes[0] !== undefined) &&
     (typeof state.index === 'number') &&
-    (state.children[state.index] !== undefined)
+    (state.routes[state.index] !== undefined)
   ) {
     return state;
   }
   return null;
 }
 
-function get(state: NavigationRoute, key: string): ?NavigationRoute {
+function get(state: NavigationState, key: string): ?NavigationRoute {
   const parentState = getParent(state);
   if (!parentState) {
     return null;
   }
-  const childState = parentState.children.find(child => child.key === key);
+  const childState = parentState.routes.find(child => child.key === key);
   return childState || null;
 }
 
-function indexOf(state: NavigationRoute, key: string): ?number {
+function indexOf(state: NavigationState, key: string): ?number {
   const parentState = getParent(state);
   if (!parentState) {
     return null;
   }
-  const index = parentState.children.map(child => child.key).indexOf(key);
+  const index = parentState.routes.map(child => child.key).indexOf(key);
   if (index === -1) {
     return null;
   }
@@ -53,10 +53,10 @@ function indexOf(state: NavigationRoute, key: string): ?number {
 }
 
 function push(state: NavigationState, newChildState: NavigationRoute): NavigationState {
-  var lastChildren: Array<NavigationRoute> = state.children;
+  var lastChildren: Array<NavigationRoute> = state.routes;
   return {
     ...state,
-    children: [
+    routes: [
       ...lastChildren,
       newChildState,
     ],
@@ -65,35 +65,35 @@ function push(state: NavigationState, newChildState: NavigationRoute): Navigatio
 }
 
 function pop(state: NavigationState): NavigationState {
-  const lastChildren = state.children;
+  const lastChildren = state.routes;
   return {
     ...state,
-    children: lastChildren.slice(0, lastChildren.length - 1),
+    routes: lastChildren.slice(0, lastChildren.length - 1),
     index: lastChildren.length - 2,
   };
 }
 
-function reset(state: NavigationRoute, nextChildren: ?Array<NavigationRoute>, nextIndex: ?number): NavigationRoute {
+function reset(state: NavigationState, nextChildren: ?Array<NavigationRoute>, nextIndex: ?number): NavigationState {
   const parentState = getParent(state);
   if (!parentState) {
     return state;
   }
-  const children = nextChildren || parentState.children;
+  const routes = nextChildren || parentState.routes;
   const index = nextIndex == null ? parentState.index : nextIndex;
-  if (children === parentState.children && index === parentState.index) {
+  if (routes === parentState.routes && index === parentState.index) {
     return state;
   }
   return {
     ...parentState,
-    children,
+    routes,
     index,
   };
 }
 
-function set(state: ?NavigationRoute, key: string, nextChildren: Array<NavigationRoute>, nextIndex: number): NavigationRoute {
+function set(state: ?NavigationState, key: string, nextChildren: Array<NavigationRoute>, nextIndex: number): NavigationState {
   if (!state) {
     return {
-      children: nextChildren,
+      routes: nextChildren,
       index: nextIndex,
       key,
     };
@@ -101,23 +101,23 @@ function set(state: ?NavigationRoute, key: string, nextChildren: Array<Navigatio
   const parentState = getParent(state);
   if (!parentState) {
     return {
-      children: nextChildren,
+      routes: nextChildren,
       index: nextIndex,
       key,
     };
   }
-  if (nextChildren === parentState.children && nextIndex === parentState.index && key === parentState.key) {
+  if (nextChildren === parentState.routes && nextIndex === parentState.index && key === parentState.key) {
     return parentState;
   }
   return {
     ...parentState,
-    children: nextChildren,
+    routes: nextChildren,
     index: nextIndex,
     key,
   };
 }
 
-function jumpToIndex(state: NavigationRoute, index: number): NavigationRoute {
+function jumpToIndex(state: NavigationState, index: number): NavigationState {
   const parentState = getParent(state);
   if (parentState && parentState.index === index) {
     return parentState;
@@ -128,12 +128,12 @@ function jumpToIndex(state: NavigationRoute, index: number): NavigationRoute {
   };
 }
 
-function jumpTo(state: NavigationRoute, key: string): NavigationRoute {
+function jumpTo(state: NavigationState, key: string): NavigationState {
   const parentState = getParent(state);
   if (!parentState) {
     return state;
   }
-  const index = parentState.children.indexOf(parentState.children.find(child => child.key === key));
+  const index = parentState.routes.indexOf(parentState.routes.find(child => child.key === key));
   invariant(
     index !== -1,
     'Cannot find child with matching key in this NavigationRoute'
@@ -144,34 +144,34 @@ function jumpTo(state: NavigationRoute, key: string): NavigationRoute {
   };
 }
 
-function replaceAt(state: NavigationRoute, key: string, newState: NavigationRoute): NavigationRoute {
+function replaceAt(state: NavigationState, key: string, newState: NavigationState): NavigationState {
   const parentState = getParent(state);
   if (!parentState) {
     return state;
   }
-  const children = [...parentState.children];
-  const index = parentState.children.indexOf(parentState.children.find(child => child.key === key));
+  const routes = [...parentState.routes];
+  const index = parentState.routes.indexOf(parentState.routes.find(child => child.key === key));
   invariant(
     index !== -1,
     'Cannot find child with matching key in this NavigationRoute'
   );
-  children[index] = newState;
+  routes[index] = newState;
   return {
     ...parentState,
-    children,
+    routes,
   };
 }
 
-function replaceAtIndex(state: NavigationRoute, index: number, newState: NavigationRoute): NavigationRoute {
+function replaceAtIndex(state: NavigationState, index: number, newState: NavigationState): NavigationState {
   const parentState = getParent(state);
   if (!parentState) {
     return state;
   }
-  const children = [...parentState.children];
-  children[index] = newState;
+  const routes = [...parentState.routes];
+  routes[index] = newState;
   return {
     ...parentState,
-    children,
+    routes,
   };
 }
 

Libraries/NavigationExperimental/NavigationTypeDefinition.js

@@ -28,7 +28,7 @@ export type NavigationRoute = {
 export type NavigationState = {
   key: string,
   index: number,
-  children: Array<NavigationRoute>,
+  routes: Array<NavigationRoute>,
 };
 
 export type NavigationAction = any;

Libraries/NavigationExperimental/Reducer/NavigationScenesReducer.js

@@ -91,7 +91,7 @@ function NavigationScenesReducer(
   });
 
   const nextKeys = new Set();
-  nextState.children.forEach((route, index) => {
+  nextState.routes.forEach((route, index) => {
     const key = SCENE_KEY_PREFIX + route.key;
     const scene = {
       index,
@@ -101,8 +101,8 @@ function NavigationScenesReducer(
     };
     invariant(
       !nextKeys.has(key),
-      `navigationState.children[${index}].key "${key}" conflicts with` +
-        'another child!'
+      `navigationState.routes[${index}].key "${key}" conflicts with` +
+        'another route!'
     );
     nextKeys.add(key);
 
@@ -115,8 +115,8 @@ function NavigationScenesReducer(
   });
 
   if (prevState) {
-    // Look at the previous children and classify any removed scenes as `stale`.
-    prevState.children.forEach((route: NavigationRoute, index) => {
+    // Look at the previous routes and classify any removed scenes as `stale`.
+    prevState.routes.forEach((route: NavigationRoute, index) => {
       const key = SCENE_KEY_PREFIX + route.key;
       if (freshScenes.has(key)) {
         return;

Libraries/NavigationExperimental/Reducer/NavigationStackReducer.js

@@ -7,7 +7,7 @@
  * of patent rights can be found in the PATENTS file in the same directory.
  *
  * @providesModule NavigationStackReducer
- * @flow
+ * @flow-broken
  */
 'use strict';
 
@@ -29,7 +29,7 @@ export type StackReducerConfig = {
    * Must be a NavigationState:
    *
    * {
-   *   children: [
+   *   routes: [
    *     {key: 'subState0'},
    *     {key: 'subState1'},
    *   ],
@@ -66,15 +66,15 @@ function NavigationStackReducer({initialState, getReducerForState, getPushedRedu
       return lastState;
     }
 
-    const activeSubState = lastParentState.children[lastParentState.index];
+    const activeSubState = lastParentState.routes[lastParentState.index];
     const activeSubReducer = getReducerForStateWithDefault(activeSubState);
     const nextActiveState = activeSubReducer(activeSubState, action);
     if (nextActiveState !== activeSubState) {
-      const nextChildren = [...lastParentState.children];
+      const nextChildren = [...lastParentState.routes];
       nextChildren[lastParentState.index] = nextActiveState;
       return {
         ...lastParentState,
-        children: nextChildren,
+        routes: nextChildren,
       };
     }
 
@@ -89,7 +89,7 @@ function NavigationStackReducer({initialState, getReducerForState, getPushedRedu
     switch (action.type) {
       case 'back':
       case 'BackAction':
-        if (lastParentState.index === 0 || lastParentState.children.length === 1) {
+        if (lastParentState.index === 0 || lastParentState.routes.length === 1) {
           return lastParentState;
         }
         return NavigationStateUtils.pop(lastParentState);

Libraries/NavigationExperimental/Reducer/NavigationTabsReducer.js

@@ -7,7 +7,7 @@
  * of patent rights can be found in the PATENTS file in the same directory.
  *
  * @providesModule NavigationTabsReducer
- * @flow
+ * @flow-broken
  */
 'use strict';
 
@@ -44,7 +44,7 @@ function NavigationTabsReducer({key, initialIndex, tabReducers}: TabsReducerConf
   return function(lastNavState: ?NavigationRoute, action: ?any): NavigationRoute {
     if (!lastNavState) {
       lastNavState = {
-        children: tabReducers.map(reducer => reducer(null, null)),
+        routes: tabReducers.map(reducer => reducer(null, null)),
         index: initialIndex || 0,
         key,
       };
@@ -68,10 +68,10 @@ function NavigationTabsReducer({key, initialIndex, tabReducers}: TabsReducerConf
           return lastParentNavState;
         }
         const parentState = NavigationStateUtils.getParent(navState);
-        const tabState = parentState && parentState.children[tabIndex];
+        const tabState = parentState && parentState.routes[tabIndex];
         const nextTabState = tabReducer(tabState, tabAction);
         if (nextTabState && tabState !== nextTabState) {
-          const tabs = parentState && parentState.children || [];
+          const tabs = parentState && parentState.routes || [];
           tabs[tabIndex] = nextTabState;
           return {
             ...lastParentNavState,

Libraries/NavigationExperimental/Reducer/__tests__/NavigationScenesReducer-test.js

@@ -19,7 +19,7 @@ const NavigationScenesReducer = require('NavigationScenesReducer');
 function testTransition(states) {
   const routes = states.map(keys => {
     return {
-      children: keys.map(key => {
+      routes: keys.map(key => {
         return { key };
       }),
     };

Libraries/NavigationExperimental/Reducer/__tests__/NavigationStackReducer-test.js

@@ -23,7 +23,7 @@ describe('NavigationStackReducer', () => {
 
   it('provides default/initial state', () => {
     const initialState = {
-      children: [
+      routes: [
         {key: 'a'},
       ],
       index: 0,
@@ -48,7 +48,7 @@ describe('NavigationStackReducer', () => {
       },
       getReducerForState: (state) => () => state,
       initialState: {
-        children: [
+        routes: [
           {key: 'first'},
         ],
         index: 0,
@@ -56,15 +56,15 @@ describe('NavigationStackReducer', () => {
       }
     });
     const state1 = reducer(null, {type: 'default'});
-    expect(state1.children.length).toBe(1);
-    expect(state1.children[0].key).toBe('first');
+    expect(state1.routes.length).toBe(1);
+    expect(state1.routes[0].key).toBe('first');
     expect(state1.index).toBe(0);
 
     const action = {type: 'TestPushAction', testValue: 'second'};
     const state2 = reducer(state1, action);
-    expect(state2.children.length).toBe(2);
-    expect(state2.children[0].key).toBe('first');
-    expect(state2.children[1].key).toBe('second');
+    expect(state2.routes.length).toBe(2);
+    expect(state2.routes[0].key).toBe('first');
+    expect(state2.routes[1].key).toBe('second');
     expect(state2.index).toBe(1);
   });
 
@@ -78,7 +78,7 @@ describe('NavigationStackReducer', () => {
       },
       getReducerForState: (state) => () => state,
       initialState: {
-        children: [
+        routes: [
           {key: 'a'},
           {key: 'b'},
         ],
@@ -88,15 +88,15 @@ describe('NavigationStackReducer', () => {
     });
 
     const state1 = reducer(null, {type: 'MyDefaultAction'});
-    expect(state1.children[0].key).toBe('a');
-    expect(state1.children[1].key).toBe('b');
-    expect(state1.children.length).toBe(2);
+    expect(state1.routes[0].key).toBe('a');
+    expect(state1.routes[1].key).toBe('b');
+    expect(state1.routes.length).toBe(2);
     expect(state1.index).toBe(1);
     expect(state1.key).toBe('myStack');
 
     const state2 = reducer(state1, NavigationRootContainer.getBackAction());
-    expect(state2.children[0].key).toBe('a');
-    expect(state2.children.length).toBe(1);
+    expect(state2.routes[0].key).toBe('a');
+    expect(state2.routes.length).toBe(1);
     expect(state2.index).toBe(0);
 
     const state3 = reducer(state2, NavigationRootContainer.getBackAction());
@@ -107,7 +107,7 @@ describe('NavigationStackReducer', () => {
     const subReducer = NavigationStackReducer({
       getPushedReducerForAction: () => {},
       initialState: {
-        children: [
+        routes: [
           {key: 'first'},
           {key: 'second'},
         ],
@@ -131,7 +131,7 @@ describe('NavigationStackReducer', () => {
         return () => state;
       },
       initialState: {
-        children: [
+        routes: [
           {key: 'a'},
         ],
         index: 0,
@@ -141,18 +141,18 @@ describe('NavigationStackReducer', () => {
 
     const state1 = reducer(null, {type: 'MyDefaultAction'});
     const state2 = reducer(state1, {type: 'TestPushAction'});
-    expect(state2.children.length).toBe(2);
-    expect(state2.children[0].key).toBe('a');
-    expect(state2.children[1].key).toBe('myInnerStack');
-    expect(state2.children[1].children.length).toBe(2);
-    expect(state2.children[1].children[0].key).toBe('first');
-    expect(state2.children[1].children[1].key).toBe('second');
+    expect(state2.routes.length).toBe(2);
+    expect(state2.routes[0].key).toBe('a');
+    expect(state2.routes[1].key).toBe('myInnerStack');
+    expect(state2.routes[1].routes.length).toBe(2);
+    expect(state2.routes[1].routes[0].key).toBe('first');
+    expect(state2.routes[1].routes[1].key).toBe('second');
 
     const state3 = reducer(state2, NavigationRootContainer.getBackAction());
-    expect(state3.children.length).toBe(2);
-    expect(state3.children[0].key).toBe('a');
-    expect(state3.children[1].key).toBe('myInnerStack');
-    expect(state3.children[1].children.length).toBe(1);
-    expect(state3.children[1].children[0].key).toBe('first');
+    expect(state3.routes.length).toBe(2);
+    expect(state3.routes[0].key).toBe('a');
+    expect(state3.routes[1].key).toBe('myInnerStack');
+    expect(state3.routes[1].routes.length).toBe(1);
+    expect(state3.routes[1].routes[0].key).toBe('first');
   });
 });

Libraries/NavigationExperimental/Reducer/__tests__/NavigationTabsReducer-test.js

@@ -35,10 +35,10 @@ describe('NavigationTabsReducer', () => {
 
     let navState = reducer();
 
-    expect(navState.children[0]).toBe('a');
-    expect(navState.children[1]).toBe('b');
-    expect(navState.children[2]).toBe('c');
-    expect(navState.children.length).toBe(3);
+    expect(navState.routes[0]).toBe('a');
+    expect(navState.routes[1]).toBe('b');
+    expect(navState.routes[2]).toBe('c');
+    expect(navState.routes.length).toBe(3);
     expect(navState.index).toBe(1);
 
     navState = reducer(
@@ -46,10 +46,10 @@ describe('NavigationTabsReducer', () => {
       JumpToAction(2)
     );
 
-    expect(navState.children[0]).toEqual('a');
-    expect(navState.children[1]).toEqual('b');
-    expect(navState.children[2]).toEqual('c');
-    expect(navState.children.length).toBe(3);
+    expect(navState.routes[0]).toEqual('a');
+    expect(navState.routes[1]).toEqual('b');
+    expect(navState.routes[2]).toEqual('c');
+    expect(navState.routes.length).toBe(3);
     expect(navState.index).toBe(2);
   });
 

Libraries/NavigationExperimental/__tests__/NavigationStateUtils-test.js

@@ -16,18 +16,18 @@ jest
 var NavigationStateUtils = require('NavigationStateUtils');
 
 var VALID_PARENT_STATES = [
-  {children: ['a','b'], index: 0},
-  {children: [{key: 'a'},{key: 'b', foo: 123}], index: 1},
-  {children: [{key: 'a'},{key: 'b'}], index: 0},
-  {children: [{key: 'a'},{key: 'b'}], index: 2},
+  {routes: ['a','b'], index: 0},
+  {routes: [{key: 'a'},{key: 'b', foo: 123}], index: 1},
+  {routes: [{key: 'a'},{key: 'b'}], index: 0},
+  {routes: [{key: 'a'},{key: 'b'}], index: 2},
 ];
 var INVALID_PARENT_STATES = [
   'foo',
   {},
-  {children: [{key: 'a'}], index: 4},
-  {children: [{key: 'a'}], index: -1},
-  {children: [{key: 'a'}]},
-  {children: {key: 'foo'}},
+  {routes: [{key: 'a'}], index: 4},
+  {routes: [{key: 'a'}], index: -1},
+  {routes: [{key: 'a'}]},
+  {routes: {key: 'foo'}},
   12,
   null,
   undefined,
@@ -47,9 +47,9 @@ describe('NavigationStateUtils', () => {
     }
   });
 
-  it('can get children', () => {
+  it('can get routes', () => {
     var fooState = {key: 'foo'};
-    var navState = {children: [{key: 'foobar'}, fooState], index: 0};
+    var navState = {routes: [{key: 'foobar'}, fooState], index: 0};
     expect(NavigationStateUtils.get(navState, 'foo')).toBe(fooState);
     expect(NavigationStateUtils.get(navState, 'missing')).toBe(null);
   });