fix(ClientRequest): support 100 continue flow

test/modules/http/request/http-request-continue.test.ts

@@ -0,0 +1,40 @@
+import { it, expect, beforeAll, afterAll } from 'vitest'
+import http from 'http'
+import { HttpServer } from '@open-draft/test-server/http'
+import { waitForClientRequest } from '../../../helpers'
+import { ClientRequestInterceptor } from '../../../../src/interceptors/ClientRequest'
+
+const interceptor = new ClientRequestInterceptor()
+
+const httpServer = new HttpServer((app) => {
+  app.get('/resource', (req, res) => {
+    res.send('original response')
+  })
+})
+
+beforeAll(async () => {
+  interceptor.apply()
+  await httpServer.listen()
+})
+
+afterAll(async () => {
+  interceptor.dispose()
+  await httpServer.close()
+})
+
+it('Unmocked request with `Expect: 100-continue` triggers continue event', async () => {
+  const body = 'this is the full request body'
+  const request = http.get(httpServer.http.url('/resource'), {
+    headers: { Expect: '100-continue' },
+  })
+  request.on('continue', () => {
+    request.end(body)
+  })
+
+  const { res, text } = await waitForClientRequest(request)
+
+  expect(res.statusCode).toBe(200)
+  expect(await text()).toBe('original response')
+})
+
+it.todo('Mocked request with `Expect: 100-continue` triggers continue event')