fix: adjust index when route names are changed

example/StackNavigator.tsx

@@ -107,10 +107,15 @@ function StackRouter(options: DefaultRouterOptions) {
     },
 
     getStateForRouteNamesChange(state, { routeNames }) {
+      const routes = state.routes.filter(route =>
+        routeNames.includes(route.name)
+      );
+
       return {
         ...state,
         routeNames,
-        routes: state.routes.filter(route => routeNames.includes(route.name)),
+        routes,
+        index: Math.min(state.index, routes.length - 1),
       };
     },
 

example/TabNavigator.tsx

@@ -91,17 +91,20 @@ function TabRouter(options: DefaultRouterOptions) {
     },
 
     getStateForRouteNamesChange(state, { routeNames, routeParamList }) {
+      const routes = routeNames.map(
+        name =>
+          state.routes.find(r => r.name === name) || {
+            name,
+            key: `${name}-${shortid()}`,
+            params: routeParamList[name],
+          }
+      );
+
       return {
         ...state,
         routeNames,
-        routes: routeNames.map(
-          name =>
-            state.routes.find(r => r.name === name) || {
-              name,
-              key: `${name}-${shortid()}`,
-              params: routeParamList[name],
-            }
-        ),
+        routes,
+        index: Math.min(state.index, routes.length - 1),
       };
     },
 

src/__tests__/__fixtures__/MockRouter.tsx

@@ -46,10 +46,15 @@ export default function MockRouter(options: DefaultRouterOptions) {
     },
 
     getStateForRouteNamesChange(state, { routeNames }) {
+      const routes = state.routes.filter(route =>
+        routeNames.includes(route.name)
+      );
+
       return {
         ...state,
         routeNames,
-        routes: state.routes.filter(route => routeNames.includes(route.name)),
+        routes,
+        index: Math.min(state.index, routes.length - 1),
       };
     },
 

src/__tests__/index.test.tsx

@@ -494,7 +494,7 @@ it('handles change in route names', () => {
   );
 
   expect(onStateChange).toBeCalledWith({
-    index: 1,
+    index: 0,
     key: '0',
     routeNames: ['foo', 'baz', 'qux'],
     routes: [{ key: 'foo', name: 'foo' }],