Revert "chore: remove e2e tests (#3146)"

This reverts commit bdcdd1d.

.github/workflows/ci.yml

@@ -63,6 +63,24 @@ jobs:
       - run: npm ci
       - run: npm run build
 
+  test-e2e:
+    needs: lint
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: Use Node.js
+        uses: actions/setup-node@v1
+        with:
+          node-version: '14.x'
+      - name: Load Node.js modules
+        uses: actions/cache@v2
+        with:
+          # npm cache files are stored in `~/.npm` on Linux/macOS
+          path: ~/.npm
+          key: ${{ runner.OS }}-node-${{ hashFiles('**/package-lock.json') }}
+      - run: npm ci
+      - run: npm run test-e2e
+
   test-frontend:
     needs: lint
     runs-on: ubuntu-latest

README.md

@@ -145,7 +145,17 @@ npm run test-ci
 
 #### End-to-end tests
 
-Removed in [#3146](https://github.com/opengovsg/FormSG/pull/3146). Will be reimplemented when the React app is ready.
+```bash
+npm run test-e2e
+```
+
+will build both the frontend and backend then run our end-to-end tests. The tests are located at [`tests/end-to-end`](./tests/end-to-end). You will need to stop the Docker dev container to be able to run the end-to-end tests.
+
+If you do not need to rebuild the frontend and backend, you can run
+
+```bash
+npm run test-e2e-ci
+```
 
 ## Architecture