👩‍💻 dx(tests): Experiment with test-only routes.

imports/ui/App.tsx

@@ -1,6 +1,6 @@
 import React from 'react';
 
-import {BrowserRouter} from 'react-router-dom';
+import {BrowserRouter, Routes, Route} from 'react-router-dom';
 
 import {CacheProvider} from '@emotion/react';
 import createCache from '@emotion/cache';
@@ -10,6 +10,8 @@ import {SnackbarProvider} from 'notistack';
 
 import CssBaseline from '@mui/material/CssBaseline';
 
+import isTest from '../app/isTest';
+
 import DateTimeLocalizationProvider from './i18n/DateTimeLocalizationProvider';
 import CustomWholeWindowDropZone from './input/CustomWholeWindowDropZone';
 import ModalProvider from './modal/ModelProvider';
@@ -24,11 +26,22 @@ export const muiCache = createCache({
 	prepend: true,
 });
 
+const Router = isTest()
+	? ({children}) => (
+			<BrowserRouter>
+				<Routes>
+					<Route element={<div>test</div>} path="/_test" />
+					<Route element={{...children}} path="*" />
+				</Routes>
+			</BrowserRouter>
+	  )
+	: BrowserRouter;
+
 const App = () => {
 	const theme = useUserTheme();
 
 	return (
-		<BrowserRouter>
+		<Router>
 			<DateTimeLocalizationProvider>
 				<CacheProvider value={muiCache}>
 					<ThemeProvider theme={theme}>
@@ -47,7 +60,7 @@ const App = () => {
 					</ThemeProvider>
 				</CacheProvider>
 			</DateTimeLocalizationProvider>
-		</BrowserRouter>
+		</Router>
 	);
 };