old_contents: import React from 'react'
  
  import {Router, Match, Miss} from './components/providers/Router'
  import {HeaderWithBackButton} from './components/HeaderWithBackButton'
  
  import Shell from './pages/Shell'
  import Beer from './pages/Beer'
  import Search from './pages/Search'
  import NotFound from './pages/NotFound'
  
  function BeerRoute({children}) {
    return <Match route={/^\/beer\/(\d+|random)\/?$/}>{children}</Match>
  }
  
  function SearchRoute({children}) {
    return <Match route={/^\/$/}>{children}</Match>
  }
  
  const App = () => {
    return (
      <Router baseUrl={'/foo' || process.env.REACT_APP_BASE_URL}>
        <Shell>
          <SearchRoute>
            <Search />
          </SearchRoute>
  
          <BeerRoute>
            <HeaderWithBackButton />
          </BeerRoute>
  
          <Miss>
            <HeaderWithBackButton />
          </Miss>
  
          <BeerRoute>
            <Beer />
          </BeerRoute>
  
          <Miss>
            <NotFound />
          </Miss>
  
        </Shell>
      </Router>
    )
  }
  
  export default App
  
new_contents: import React from 'react'
  
  import {Router, Match, Miss} from './components/providers/Router'
  import {HeaderWithBackButton} from './components/HeaderWithBackButton'
  
  import Shell from './pages/Shell'
  import Beer from './pages/Beer'
  import Search from './pages/Search'
  import NotFound from './pages/NotFound'
  
  function BeerRoute({children}) {
    return <Match route={/^\/beer\/(\d+|random)\/?$/}>{children}</Match>
  }
  
  function SearchRoute({children}) {
    return <Match route={/^\/$/}>{children}</Match>
  }
  
  const App = () => {
    return (
      <Router baseUrl={process.env.REACT_APP_BASE_URL}>
        <Shell>
          <SearchRoute>
            <Search />
          </SearchRoute>
  
          <BeerRoute>
            <HeaderWithBackButton />
          </BeerRoute>
  
          <Miss>
            <HeaderWithBackButton />
          </Miss>
  
          <BeerRoute>
            <Beer />
          </BeerRoute>
  
          <Miss>
            <NotFound />
          </Miss>
  
        </Shell>
      </Router>
    )
  }
  
  export default App
  
subject: Remove mocked baseUrl