Make Router({ RouteName: Component }) a valid way to configure a router (#3486)

* Make Router({routeName: Component}) a valid way to instantiate a route

* Update App.js in NavigationPlayground

* Fix route config flow type

src/routers/__tests__/createConfigGetter-test.js

@@ -175,23 +175,3 @@ test('should throw if the route does not exist', () => {
     "There is no route defined for key Settings.\nMust be one of: 'Home'"
   );
 });
-
-test('should throw if the screen is not defined under the route config', () => {
-  /* eslint-disable react/no-multi-comp */
-
-  const getScreenOptions = createConfigGetter({
-    Home: {},
-  });
-
-  const routes = [{ key: 'B', routeName: 'Home' }];
-
-  expect(() =>
-    getScreenOptions(
-      addNavigationHelpers({
-        state: routes[0],
-        dispatch: () => false,
-        addListener: dummyEventSubscriber,
-      })
-    )
-  ).toThrowError('Route Home must define a screen or a getScreen.');
-});

src/routers/__tests__/validateRouteConfigMap-test.js

@@ -39,9 +39,7 @@ describe('validateRouteConfigMap', () => {
       Home: {
         screen: ProfileNavigator,
       },
-      Chat: {
-        screen: ListScreen,
-      },
+      Chat: ListScreen,
     };
     validateRouteConfigMap(invalidMap);
   });

src/routers/getScreenForRouteName.js

@@ -32,5 +32,5 @@ export default function getScreenForRouteName(routeConfigs, routeName) {
     return screen;
   }
 
-  throw new Error(`Route ${routeName} must define a screen or a getScreen.`);
+  return routeConfig;
 }

src/routers/validateRouteConfigMap.js

@@ -14,44 +14,37 @@ function validateRouteConfigMap(routeConfigs) {
   routeNames.forEach(routeName => {
     const routeConfig = routeConfigs[routeName];
 
-    if (!routeConfig.screen && !routeConfig.getScreen) {
-      throw new Error(
-        `Route '${routeName}' should declare a screen. ` +
-          'For example:\n\n' +
-          "import MyScreen from './MyScreen';\n" +
-          '...\n' +
-          `${routeName}: {\n` +
-          '  screen: MyScreen,\n' +
-          '}'
-      );
-    } else if (routeConfig.screen && routeConfig.getScreen) {
-      throw new Error(
-        `Route '${routeName}' should declare a screen or ` +
-          'a getScreen, not both.'
-      );
-    }
+    const screenComponent = routeConfig.screen
+      ? routeConfig.screen
+      : routeConfig;
 
     if (
-      routeConfig.screen &&
-      typeof routeConfig.screen !== 'function' &&
-      typeof routeConfig.screen !== 'string'
+      screenComponent &&
+      typeof screenComponent !== 'function' &&
+      typeof screenComponent !== 'string' &&
+      !routeConfig.getScreen
     ) {
       throw new Error(
         `The component for route '${routeName}' must be a ` +
           'React component. For example:\n\n' +
           "import MyScreen from './MyScreen';\n" +
           '...\n' +
-          `${routeName}: {\n` +
-          '  screen: MyScreen,\n' +
+          `${routeName}: MyScreen,\n` +
           '}\n\n' +
           'You can also use a navigator:\n\n' +
           "import MyNavigator from './MyNavigator';\n" +
           '...\n' +
-          `${routeName}: {\n` +
-          '  screen: MyNavigator,\n' +
+          `${routeName}: MyNavigator,\n` +
           '}'
       );
     }
+
+    if (routeConfig.screen && routeConfig.getScreen) {
+      throw new Error(
+        `Route '${routeName}' should declare a screen or ` +
+          'a getScreen, not both.'
+      );
+    }
   });
 }