fix: return correct value for isFocused after changing screens

fixes #7843

packages/core/src/__tests__/useNavigationCache.test.tsx

@@ -1,7 +1,10 @@
 import * as React from 'react';
-import { render } from 'react-native-testing-library';
+import { render, act } from 'react-native-testing-library';
 import useEventEmitter from '../useEventEmitter';
 import useNavigationCache from '../useNavigationCache';
+import useNavigationBuilder from '../useNavigationBuilder';
+import BaseNavigationContainer from '../BaseNavigationContainer';
+import Screen from '../Screen';
 import MockRouter, { MockRouterKey } from './__fixtures__/MockRouter';
 
 beforeEach(() => (MockRouterKey.current = 0));
@@ -56,3 +59,136 @@ it('preserves reference for navigation objects', () => {
 
   root.update(<Test />);
 });
+
+it('returns correct value for isFocused', () => {
+  const TestNavigator = (props: any): any => {
+    const { state, descriptors } = useNavigationBuilder(MockRouter, props);
+
+    return state.routes.map(route => descriptors[route.key].render());
+  };
+
+  let navigation: any;
+
+  const Test = (props: any) => {
+    navigation = props.navigation;
+
+    return null;
+  };
+
+  render(
+    <BaseNavigationContainer>
+      <TestNavigator>
+        <Screen name="first">{() => null}</Screen>
+        <Screen name="second" component={Test} />
+        <Screen name="third">{() => null}</Screen>
+      </TestNavigator>
+    </BaseNavigationContainer>
+  );
+
+  expect(navigation.isFocused()).toBe(false);
+
+  act(() => navigation.navigate('second'));
+
+  expect(navigation.isFocused()).toBe(true);
+
+  act(() => navigation.navigate('third'));
+
+  expect(navigation.isFocused()).toBe(false);
+
+  act(() => navigation.navigate('second'));
+
+  expect(navigation.isFocused()).toBe(true);
+});
+
+it('returns correct value for isFocused after changing screens', () => {
+  const TestRouter = (
+    options: Parameters<typeof MockRouter>[0]
+  ): ReturnType<typeof MockRouter> => {
+    const router = MockRouter(options);
+
+    return {
+      ...router,
+
+      getStateForRouteNamesChange(state, { routeNames }) {
+        const routes = routeNames.map(
+          name =>
+            state.routes.find(r => r.name === name) || {
+              name,
+              key: name,
+            }
+        );
+
+        return {
+          ...state,
+          routeNames,
+          routes,
+          index: routes.length - 1,
+        };
+      },
+    };
+  };
+
+  const TestNavigator = (props: any): any => {
+    const { state, descriptors } = useNavigationBuilder(TestRouter, props);
+
+    return state.routes.map(route => descriptors[route.key].render());
+  };
+
+  let navigation: any;
+
+  const Test = (props: any) => {
+    navigation = props.navigation;
+
+    return null;
+  };
+
+  const root = render(
+    <BaseNavigationContainer>
+      <TestNavigator>
+        <Screen name="first">{() => null}</Screen>
+        <Screen name="second" component={Test} />
+        <Screen name="third">{() => null}</Screen>
+      </TestNavigator>
+    </BaseNavigationContainer>
+  );
+
+  expect(navigation.isFocused()).toBe(false);
+
+  root.update(
+    <BaseNavigationContainer>
+      <TestNavigator>
+        <Screen name="first">{() => null}</Screen>
+        <Screen name="third">{() => null}</Screen>
+        <Screen name="second" component={Test} />
+      </TestNavigator>
+    </BaseNavigationContainer>
+  );
+
+  expect(navigation.isFocused()).toBe(true);
+
+  root.update(
+    <BaseNavigationContainer>
+      <TestNavigator>
+        <Screen name="first">{() => null}</Screen>
+        <Screen name="third">{() => null}</Screen>
+        <Screen name="fourth">{() => null}</Screen>
+        <Screen name="second" component={Test} />
+      </TestNavigator>
+    </BaseNavigationContainer>
+  );
+
+  expect(navigation.isFocused()).toBe(true);
+
+  root.update(
+    <BaseNavigationContainer>
+      <TestNavigator>
+        <Screen name="first">{() => null}</Screen>
+        <Screen name="third">{() => null}</Screen>
+        <Screen name="second" component={Test} />
+        <Screen name="fourth">{() => null}</Screen>
+      </TestNavigator>
+    </BaseNavigationContainer>
+  );
+
+  expect(navigation.isFocused()).toBe(false);
+});

packages/core/src/useNavigationCache.tsx

@@ -63,7 +63,7 @@ export default function useNavigationCache<
   };
 
   cache.current = state.routes.reduce<NavigationCache<State, ScreenOptions>>(
-    (acc, route, index) => {
+    (acc, route) => {
       const previous = cache.current[route.key];
 
       if (previous) {
@@ -110,7 +110,7 @@ export default function useNavigationCache<
           isFocused: () => {
             const state = getState();
 
-            if (index !== state.index) {
+            if (state.routes[state.index].key !== route.key) {
               return false;
             }