test: set up test suite with Jest and MSW

.github/workflows/ci.yml

@@ -25,23 +25,23 @@ jobs:
       - run: npm ci
       - run: npx lockfile-lint --type npm --path package-lock.json --validate-https --allowed-hosts npm
       - run: npm run lint
-  # test:
-  #   name: Test
-  #   runs-on: ubuntu-18.04
-  #   steps:
-  #     - uses: actions/checkout@v2
-  #     - name: Use Node.js
-  #       uses: actions/setup-node@v1
-  #       with:
-  #         node-version: '16.x'
-  #     - name: Cache 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') }}
-  #         restore-keys: |
-  #           ${{ runner.OS }}-node-
-  #           ${{ runner.OS }}-
-  #     - run: npm ci
-  #     - run: npm test
+  test:
+    name: Test
+    runs-on: ubuntu-18.04
+    steps:
+      - uses: actions/checkout@v2
+      - name: Use Node.js
+        uses: actions/setup-node@v1
+        with:
+          node-version: '16.x'
+      - name: Cache 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') }}
+          restore-keys: |
+            ${{ runner.OS }}-node-
+            ${{ runner.OS }}-
+      - run: npm ci
+      - run: npm test

jest.config.js

@@ -0,0 +1,6 @@
+/** @type {import('ts-jest').JestConfigWithTsJest} */
+module.exports = {
+  preset: 'ts-jest',
+  testEnvironment: 'node',
+  setupFilesAfterEnv: ['./jest.setup.js'],
+}

jest.setup.js

@@ -0,0 +1,23 @@
+/* eslint-disable */
+
+const { server } = require('./test/mocks/server.ts')
+
+// Establish API mocking before all tests.
+beforeAll(() =>
+  server.listen({
+    // Ensure MSW intercepts all requests
+    onUnhandledRequest(req) {
+      console.error(
+        'Found an unhandled %s request to %s',
+        req.method,
+        req.url.href,
+      )
+      throw new Error('Attempted to make network request which is not mocked')
+    },
+  }),
+)
+// Reset any request handlers that we may add during the tests,
+// so they don't affect other tests.
+afterEach(() => server.resetHandlers())
+// Clean up after the tests are finished.
+afterAll(() => server.close())