Authentication component that tracks user authentication status

frontend/package.json

@@ -8,6 +8,7 @@
     "@testing-library/user-event": "^7.2.1",
     "bootstrap": "^4.5.0",
     "firebase": "^7.15.5",
+    "history": "^5.0.0",
     "react": "^16.13.1",
     "react-bootstrap": "^1.0.1",
     "react-dom": "^16.13.1",

frontend/src/components/App/index.js

@@ -1,5 +1,6 @@
 import React from 'react';
 import {BrowserRouter as Router, Route} from 'react-router-dom';
+import { AuthProvider, PrivateRoute } from '../Auth';
 
 import LandingPage from '../Landing';
 import SignInPage from '../SignIn'
@@ -14,14 +15,16 @@ import * as ROUTES from '../../constants/routes';
 class App extends React.Component {
   render() {
     return (
-      <Router>
-        <div>
-          <Route exact path={ROUTES.LANDING} component={LandingPage} />
-          <Route path={ROUTES.SIGN_IN} component={SignInPage} />
-          <Route path={ROUTES.VIEW_TRIPS} component={ViewTripsPage} />
-          <Route path={ROUTES.VIEW_ACTIVITIES} component={ViewActivitiesPage} />
-        </div>
-      </Router>
+      <AuthProvider>
+        <Router>
+          <div>
+            <Route exact path={ROUTES.LANDING} component={LandingPage} />
+            <Route path={ROUTES.SIGN_IN} component={SignInPage} />
+            <PrivateRoute path={ROUTES.VIEW_TRIPS} component={ViewTripsPage} />
+            <PrivateRoute path={ROUTES.VIEW_ACTIVITIES + '/:tripId'} component={ViewActivitiesPage} />
+          </div>
+        </Router>
+      </AuthProvider>
     );
   }
 };

frontend/src/components/Auth/AuthContext.js

@@ -0,0 +1,36 @@
+import React, { useState, useEffect } from 'react';
+import app from '../Firebase';
+
+const AuthContext = React.createContext();
+
+/**
+ * AuthProvider component that keeps track of the authentication status of the
+ * current user. Allows global use of this status using React Context and should
+ * be wrapped around the contents of the App component.
+ */
+const AuthProvider = (props) => {
+  const [currentUser, setCurrentUser] = useState(null);
+  const [isLoading, setIsLoading] = useState(true);
+
+  useEffect(() => {
+    // Set up listener that changes user status whenever it is updated.
+    app.auth().onAuthStateChanged((user) => {
+      setCurrentUser(user);
+      setIsLoading(false);
+    });
+  }, []);
+
+  if (isLoading) {
+    // TODO (Issue #25): Page initially displays "Loading..." for testing
+    // purposes, make this blank in the deployed build.
+    return ( <h1>Loading...</h1> );
+  }
+
+  return (
+    <AuthContext.Provider value={currentUser}>
+      {props.children}
+    </AuthContext.Provider>
+  );
+}
+
+export { AuthContext, AuthProvider };

frontend/src/components/Auth/AuthContext.test.js

@@ -0,0 +1,80 @@
+import React, { useContext } from 'react';
+import { render, act, screen, cleanup } from '@testing-library/react';
+import { AuthContext, AuthProvider } from './AuthContext.js';
+
+jest.useFakeTimers();
+
+// All times are in milliseconds.
+const TIME_BEFORE_USER_IS_LOADED = 500;
+const TIME_WHEN_USER_IS_LOADED = 1000;
+const TIME_AFTER_USER_IS_LOADED = 2000;
+
+// Mock the the Firebase Auth onAuthStateChanged function, which pauses for the
+// time given by TIME_WHEN_USER_IS_LOADED, then returns a fake user with only
+// the property `name: 'Keiffer'`.
+const mockOnAuthStateChanged = jest.fn(callback => {
+  setTimeout(() => {
+    callback({ name: 'Keiffer' })
+  }, TIME_WHEN_USER_IS_LOADED);
+});
+jest.mock('firebase/app', () => {
+  return {
+    initializeApp: () => {
+      return {
+        auth: () => {
+          return {
+            onAuthStateChanged: mockOnAuthStateChanged
+          }
+        }
+      }
+    }
+  }
+});
+
+afterEach(cleanup);
+
+describe('AuthProvider component', () => {
+  beforeEach(() => { render(<AuthProvider />) });
+
+  it('initially displays "Loading"', () => {
+    act(() => jest.advanceTimersByTime(TIME_BEFORE_USER_IS_LOADED));
+    expect(screen.getByText('Loading...')).toBeInTheDocument();
+  });
+
+  it('returns a provider when onAuthStateChanged is called', () => {
+    act(() => jest.advanceTimersByTime(TIME_AFTER_USER_IS_LOADED));
+    expect(screen.queryByText('Loading...')).not.toBeInTheDocument();
+  });
+});
+
+describe('AuthContext Consumer component', () => {
+  // A Consumer component for AuthContext that just displays the current
+  // user.
+  const TestAuthContextConsumerComponent = () => {
+    const currentUser = useContext(AuthContext);
+
+    return (
+      <div>
+        <div>{currentUser.name}</div>
+      </div>
+    );
+  };
+
+  beforeEach(() => {
+    render(
+      <AuthProvider>
+        <TestAuthContextConsumerComponent />
+      </AuthProvider>
+    );
+  });
+
+  it('initially displays "Loading"', () => {
+    act(() => jest.advanceTimersByTime(TIME_BEFORE_USER_IS_LOADED));
+    expect(screen.getByText('Loading...')).toBeInTheDocument();
+  });
+
+  it('displays the current user when they are authenticated', () => {
+    act(() => jest.advanceTimersByTime(TIME_AFTER_USER_IS_LOADED));
+    expect(screen.getByText('Keiffer')).toBeInTheDocument();
+  });
+});

frontend/src/components/Auth/PrivateRoute.js

@@ -0,0 +1,27 @@
+import React, { useContext } from 'react';
+import { Route, Redirect } from 'react-router-dom';
+import { AuthContext } from '../Auth';
+
+import { SIGN_IN } from '../../constants/routes.js';
+
+/**
+ * PrivateRoute component that takes the authentication status of the current
+ * user from AuthContext. If they are authenticated, they will be allowed to
+ * view the contents of the Route component. If they are not authenticated, they
+ * will be redirected to the SIGN_IN page.
+ */
+const PrivateRoute = ({ component: RouteComponent, ...rest }) => {
+  const currentUser = useContext(AuthContext);
+
+  return (
+    <Route
+      {...rest}
+      render={routeProps =>
+        currentUser ? <RouteComponent {...routeProps} />
+                    : <Redirect to={SIGN_IN} />
+      }
+    />
+  );
+}
+
+export default PrivateRoute;

frontend/src/components/Auth/PrivateRoute.test.js

@@ -0,0 +1,50 @@
+import React from 'react';
+import { Router, Route } from 'react-router-dom';
+import { render, screen, cleanup } from '@testing-library/react';
+import { createMemoryHistory } from 'history';
+import PrivateRoute from './PrivateRoute.js';
+
+import { SIGN_IN } from '../../constants/routes.js';
+
+const history = createMemoryHistory();
+
+// Mock the useContext function so that, when called in the PrivateRoute
+// component, returns null the first time and a fake user the second time.
+jest.mock('react', () => (
+  {
+    ...(jest.requireActual('react')),
+    useContext: jest
+      .fn()
+      .mockReturnValueOnce(null)
+      .mockReturnValueOnce({ name: 'Keiffer' })
+  }
+));
+
+describe('PrivateRoute component', () => {
+  const TestComponent = () => {
+    return (
+      <div>Hello, World!</div>
+    );
+  };
+
+  beforeEach(() => {
+    render(
+      <Router history={history}>
+        <PrivateRoute component={TestComponent} />
+        <Route path={SIGN_IN} />
+      </Router>
+    );
+  });
+
+  afterEach(cleanup);
+
+  // mockOnAuthStateChanged called first time, so user should be null.
+  it('redirects to SIGN_IN when the user is not authenticated', () => {
+    expect(history.location.pathname).toEqual(SIGN_IN);
+  });
+
+  // mockOnAuthStateChanged called second time, so user should not be null.
+  it('renders the given component when the user is authenticated', () => {
+    expect(screen.getByText('Hello, World!')).toBeInTheDocument();
+  });
+});

frontend/src/components/Auth/index.js

@@ -0,0 +1,4 @@
+import { AuthContext, AuthProvider } from './AuthContext.js';
+import PrivateRoute from './PrivateRoute.js';
+
+export { AuthContext, AuthProvider, PrivateRoute };