Fix regression in error message for route config validation

src/routers/__tests__/__snapshots__/validateRouteConfigMap-test.js.snap

@@ -0,0 +1,37 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`validateRouteConfigMap Fails if both screen and getScreen are defined 1`] = `"Route 'Home' should declare a screen or a getScreen, not both."`;
+
+exports[`validateRouteConfigMap Fails on bad object 1`] = `
+"The component for route 'Home' must be a React component. For example:
+
+import MyScreen from './MyScreen';
+...
+Home: MyScreen,
+}
+
+You can also use a navigator:
+
+import MyNavigator from './MyNavigator';
+...
+Home: MyNavigator,
+}"
+`;
+
+exports[`validateRouteConfigMap Fails on empty bare screen 1`] = `
+"The component for route 'Home' must be a React component. For example:
+
+import MyScreen from './MyScreen';
+...
+Home: MyScreen,
+}
+
+You can also use a navigator:
+
+import MyNavigator from './MyNavigator';
+...
+Home: MyNavigator,
+}"
+`;
+
+exports[`validateRouteConfigMap Fails on empty config 1`] = `"Please specify at least one route when configuring a navigator."`;

src/routers/__tests__/validateRouteConfigMap-test.js

@@ -13,9 +13,19 @@ ProfileNavigator.router = StackRouter({
 });
 
 describe('validateRouteConfigMap', () => {
+  test('Fails on empty bare screen', () => {
+    const invalidMap = {
+      Home: undefined,
+    };
+    expect(() =>
+      validateRouteConfigMap(invalidMap)
+    ).toThrowErrorMatchingSnapshot();
+  });
   test('Fails on empty config', () => {
     const invalidMap = {};
-    expect(() => validateRouteConfigMap(invalidMap)).toThrow();
+    expect(() =>
+      validateRouteConfigMap(invalidMap)
+    ).toThrowErrorMatchingSnapshot();
   });
   test('Fails on bad object', () => {
     const invalidMap = {
@@ -23,7 +33,9 @@ describe('validateRouteConfigMap', () => {
         foo: 'bar',
       },
     };
-    expect(() => validateRouteConfigMap(invalidMap)).toThrow();
+    expect(() =>
+      validateRouteConfigMap(invalidMap)
+    ).toThrowErrorMatchingSnapshot();
   });
   test('Fails if both screen and getScreen are defined', () => {
     const invalidMap = {
@@ -32,15 +44,17 @@ describe('validateRouteConfigMap', () => {
         getScreen: () => ListScreen,
       },
     };
-    expect(() => validateRouteConfigMap(invalidMap)).toThrow();
+    expect(() =>
+      validateRouteConfigMap(invalidMap)
+    ).toThrowErrorMatchingSnapshot();
   });
   test('Succeeds on a valid config', () => {
-    const invalidMap = {
+    const validMap = {
       Home: {
         screen: ProfileNavigator,
       },
       Chat: ListScreen,
     };
-    validateRouteConfigMap(invalidMap);
+    validateRouteConfigMap(validMap);
   });
 });

src/routers/validateRouteConfigMap.js

@@ -13,16 +13,13 @@ function validateRouteConfigMap(routeConfigs) {
 
   routeNames.forEach(routeName => {
     const routeConfig = routeConfigs[routeName];
-
-    const screenComponent = routeConfig.screen
-      ? routeConfig.screen
-      : routeConfig;
+    const screenComponent = getScreenComponent(routeConfig);
 
     if (
-      screenComponent &&
-      typeof screenComponent !== 'function' &&
-      typeof screenComponent !== 'string' &&
-      !routeConfig.getScreen
+      !screenComponent ||
+      (typeof screenComponent !== 'function' &&
+        typeof screenComponent !== 'string' &&
+        !routeConfig.getScreen)
     ) {
       throw new Error(
         `The component for route '${routeName}' must be a ` +
@@ -48,4 +45,12 @@ function validateRouteConfigMap(routeConfigs) {
   });
 }
 
+function getScreenComponent(routeConfig) {
+  if (!routeConfig) {
+    return null;
+  }
+
+  return routeConfig.screen ? routeConfig.screen : routeConfig;
+}
+
 export default validateRouteConfigMap;