fix: don't throw when switching navigator. fixes #91

packages/core/src/EnsureSingleNavigator.tsx

@@ -18,25 +18,30 @@ export const SingleNavigatorContext = React.createContext<
  * Component which ensures that there's only one navigator nested under it.
  */
 export default function EnsureSingleNavigator({ children }: Props) {
-  const [currentKey, setCurrentKey] = React.useState<string | undefined>();
+  const navigatorKeyRef = React.useRef<string | undefined>();
+
   const value = React.useMemo(
     () => ({
       register(key: string) {
+        const currentKey = navigatorKeyRef.current;
+
         if (currentKey !== undefined && key !== currentKey) {
           throw new Error(MULTIPLE_NAVIGATOR_ERROR);
         }
 
-        setCurrentKey(key);
+        navigatorKeyRef.current = key;
       },
       unregister(key: string) {
-        if (currentKey !== undefined && key !== currentKey) {
-          throw new Error(MULTIPLE_NAVIGATOR_ERROR);
+        const currentKey = navigatorKeyRef.current;
+
+        if (key !== currentKey) {
+          return;
         }
 
-        setCurrentKey(undefined);
+        navigatorKeyRef.current = undefined;
       },
     }),
-    [currentKey]
+    []
   );
 
   return (

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

@@ -695,3 +695,30 @@ it('throws when multiple screens with same name are defined', () => {
     "A navigator cannot contain multiple 'Screen' components with the same name (found duplicate screen named 'foo')"
   );
 });
+
+it('switches rendered navigators', () => {
+  const TestNavigator = (props: any) => {
+    useNavigationBuilder(MockRouter, props);
+    return null;
+  };
+
+  const root = render(
+    <NavigationContainer>
+      <TestNavigator key="a">
+        <Screen name="foo" component={jest.fn()} />
+      </TestNavigator>
+    </NavigationContainer>
+  );
+
+  expect(() =>
+    root.update(
+      <NavigationContainer>
+        <TestNavigator key="b">
+          <Screen name="foo" component={jest.fn()} />
+        </TestNavigator>
+      </NavigationContainer>
+    )
+  ).not.toThrowError(
+    'Another navigator is already registered for this container.'
+  );
+});