Adds integration tests for bypass/fall-through response patching beha…

…viors

test/msw-api/setup-server/scenarios/response-patching.test.ts

@@ -0,0 +1,83 @@
+/**
+ * @jest-environment node
+ */
+import fetch from 'node-fetch'
+import { rest } from 'msw'
+import { setupServer } from 'msw/node'
+
+const server = setupServer(
+  rest.get('https://test.mswjs.io/user', async (req, res, ctx) => {
+    const originalResponse = await ctx.fetch('https://httpbin.org/get')
+
+    return res(
+      ctx.json({
+        url: originalResponse.url,
+        mocked: true,
+      }),
+    )
+  }),
+  rest.get('https://test.mswjs.io/complex-request', async (req, res, ctx) => {
+    const bypass = req.url.searchParams.get('bypass')
+    const shouldBypass = bypass === 'true'
+    const performRequest = shouldBypass
+      ? () => ctx.fetch('https://httpbin.org/post', { method: 'POST' })
+      : () =>
+          fetch('https://httpbin.org/post', { method: 'POST' }).then((res) =>
+            res.json(),
+          )
+    const originalResponse = await performRequest()
+
+    return res(
+      ctx.json({
+        url: originalResponse.url,
+        mocked: true,
+      }),
+    )
+  }),
+  rest.post('https://httpbin.org/post', (req, res, ctx) => {
+    return res(ctx.json({ url: 'completely-mocked' }))
+  }),
+)
+
+beforeAll(() => server.listen())
+afterEach(() => server.resetHandlers())
+afterAll(() => server.close())
+
+test('returns a combination of mocked and original responses', async () => {
+  const res = await fetch('https://test.mswjs.io/user')
+  const { status, headers } = res
+  const body = await res.json()
+
+  expect(status).toBe(200)
+  expect(headers.get('x-powered-by')).toBe('msw')
+  expect(body).toEqual({
+    url: 'https://httpbin.org/get',
+    mocked: true,
+  })
+})
+
+test('bypasses a mocked request when using "ctx.fetch"', async () => {
+  const res = await fetch('https://test.mswjs.io/complex-request?bypass=true')
+  const { status, headers } = res
+  const body = await res.json()
+
+  expect(status).toBe(200)
+  expect(headers.get('x-powered-by')).toBe('msw')
+  expect(body).toEqual({
+    url: 'https://httpbin.org/post',
+    mocked: true,
+  })
+})
+
+test('falls into the mocked request when using "fetch" directly', async () => {
+  const res = await fetch('https://test.mswjs.io/complex-request')
+  const { status, headers } = res
+  const body = await res.json()
+
+  expect(status).toBe(200)
+  expect(headers.get('x-powered-by')).toBe('msw')
+  expect(body).toEqual({
+    url: 'completely-mocked',
+    mocked: true,
+  })
+})