Add integration tests

test/integration/optional-chaining-nullish-coalescing/pages/nullish-coalescing.js

@@ -0,0 +1,9 @@
+let hello
+let another = ''
+
+export default () => (
+  <>
+    <p>result1: {hello ?? 'fallback'}</p>
+    <p>result2: {another ?? 'fallback'}</p>
+  </>
+)

test/integration/optional-chaining-nullish-coalescing/pages/optional-chaining.js

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+let hello
+let another = { thing: 1 }
+
+export default () => (
+  <>
+    <p>result1: {hello?.world ? 'something' : 'nothing'}</p>
+    <p>result2: {another?.thing ? 'something' : 'nothing'}</p>
+  </>
+)

test/integration/optional-chaining-nullish-coalescing/test/index.test.js

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+/* eslint-env jest */
+/* global jasmine */
+import fs from 'fs-extra'
+import { join } from 'path'
+import {
+  renderViaHTTP,
+  launchApp,
+  nextBuild,
+  nextStart,
+  killApp,
+  findPort,
+} from 'next-test-utils'
+
+jasmine.DEFAULT_TIMEOUT_INTERVAL = 1000 * 60 * 2
+
+const appDir = join(__dirname, '..')
+const nextConfig = join(appDir, 'next.config.js')
+let appPort
+let app
+
+const runTests = () => {
+  it('should support optional chaining', async () => {
+    const html = await renderViaHTTP(appPort, '/optional-chaining')
+    expect(html).toMatch(/result1:.*?nothing/)
+    expect(html).toMatch(/result2:.*?something/)
+  })
+
+  it('should support nullish coalescing', async () => {
+    const html = await renderViaHTTP(appPort, '/nullish-coalescing')
+    expect(html).toMatch(/result1:.*?fallback/)
+    expect(html).not.toMatch(/result2:.*?fallback/)
+  })
+}
+
+describe('Optional chaining and nullish coalescing support', () => {
+  describe('dev mode', () => {
+    beforeAll(async () => {
+      appPort = await findPort()
+      app = await launchApp(appDir, appPort)
+    })
+    afterAll(() => killApp(app))
+
+    runTests()
+  })
+
+  describe('server mode', () => {
+    beforeAll(async () => {
+      await fs.remove(nextConfig)
+      await nextBuild(appDir)
+      appPort = await findPort()
+      app = await nextStart(appDir, appPort)
+    })
+    afterAll(() => killApp(app))
+
+    runTests()
+  })
+
+  describe('serverless mode', () => {
+    beforeAll(async () => {
+      await fs.writeFile(
+        nextConfig,
+        `module.exports = { target: 'serverless' }`
+      )
+      await nextBuild(appDir)
+      appPort = await findPort()
+      app = await nextStart(appDir, appPort)
+    })
+    afterAll(async () => {
+      await killApp(app)
+      await fs.remove(nextConfig)
+    })
+
+    runTests()
+  })
+})