Install msw

TypeScript has to be temporarily bumped because msw listed it as a
optional peerDependency with an incompatibile version range, which
is a strange thing to do IMO, but nevertheless this shouldn't be an
issue in the long run, since open-telemetry#5145 will bump us to 5.0 anyway.

experimental/packages/opentelemetry-instrumentation-fetch/karma.conf.js

@@ -17,8 +17,14 @@
 const karmaWebpackConfig = require('../../../karma.webpack');
 const karmaBaseConfig = require('../../../karma.base');
 
-module.exports = (config) => {
-  config.set(Object.assign({}, karmaBaseConfig, {
-    webpack: karmaWebpackConfig
-  }))
+module.exports = config => {
+  config.set(
+    Object.assign({}, karmaBaseConfig, {
+      proxies: {
+        '/mockServiceWorker.js': '/base/test/mockServiceWorker.js',
+      },
+      files: [...karmaBaseConfig.files, 'test/mockServiceWorker.js'],
+      webpack: karmaWebpackConfig,
+    })
+  );
 };

experimental/packages/opentelemetry-instrumentation-fetch/package.json

@@ -75,10 +75,11 @@
     "karma-webpack": "5.0.1",
     "lerna": "6.6.2",
     "mocha": "10.8.2",
+    "msw": "2.7.0",
     "nyc": "15.1.0",
     "sinon": "15.1.2",
     "ts-loader": "9.5.1",
-    "typescript": "4.4.4",
+    "typescript": "4.8.4",
     "webpack": "5.96.1",
     "webpack-cli": "5.1.4",
     "webpack-merge": "5.10.0"
@@ -93,5 +94,10 @@
     "@opentelemetry/semantic-conventions": "1.28.0"
   },
   "homepage": "https://github.com/open-telemetry/opentelemetry-js/tree/main/experimental/packages/opentelemetry-instrumentation-fetch",
-  "sideEffects": false
-}
+  "sideEffects": false,
+  "msw": {
+    "workerDirectory": [
+      "test"
+    ]
+  }
+}

experimental/packages/opentelemetry-instrumentation-fetch/test/mockServiceWorker.js

@@ -0,0 +1,307 @@
+/* eslint-disable */
+/* tslint:disable */
+
+/**
+ * Mock Service Worker.
+ * @see https://github.com/mswjs/msw
+ * - Please do NOT modify this file.
+ * - Please do NOT serve this file on production.
+ */
+
+const PACKAGE_VERSION = '2.7.0'
+const INTEGRITY_CHECKSUM = '00729d72e3b82faf54ca8b9621dbb96f'
+const IS_MOCKED_RESPONSE = Symbol('isMockedResponse')
+const activeClientIds = new Set()
+
+self.addEventListener('install', function () {
+  self.skipWaiting()
+})
+
+self.addEventListener('activate', function (event) {
+  event.waitUntil(self.clients.claim())
+})
+
+self.addEventListener('message', async function (event) {
+  const clientId = event.source.id
+
+  if (!clientId || !self.clients) {
+    return
+  }
+
+  const client = await self.clients.get(clientId)
+
+  if (!client) {
+    return
+  }
+
+  const allClients = await self.clients.matchAll({
+    type: 'window',
+  })
+
+  switch (event.data) {
+    case 'KEEPALIVE_REQUEST': {
+      sendToClient(client, {
+        type: 'KEEPALIVE_RESPONSE',
+      })
+      break
+    }
+
+    case 'INTEGRITY_CHECK_REQUEST': {
+      sendToClient(client, {
+        type: 'INTEGRITY_CHECK_RESPONSE',
+        payload: {
+          packageVersion: PACKAGE_VERSION,
+          checksum: INTEGRITY_CHECKSUM,
+        },
+      })
+      break
+    }
+
+    case 'MOCK_ACTIVATE': {
+      activeClientIds.add(clientId)
+
+      sendToClient(client, {
+        type: 'MOCKING_ENABLED',
+        payload: {
+          client: {
+            id: client.id,
+            frameType: client.frameType,
+          },
+        },
+      })
+      break
+    }
+
+    case 'MOCK_DEACTIVATE': {
+      activeClientIds.delete(clientId)
+      break
+    }
+
+    case 'CLIENT_CLOSED': {
+      activeClientIds.delete(clientId)
+
+      const remainingClients = allClients.filter((client) => {
+        return client.id !== clientId
+      })
+
+      // Unregister itself when there are no more clients
+      if (remainingClients.length === 0) {
+        self.registration.unregister()
+      }
+
+      break
+    }
+  }
+})
+
+self.addEventListener('fetch', function (event) {
+  const { request } = event
+
+  // Bypass navigation requests.
+  if (request.mode === 'navigate') {
+    return
+  }
+
+  // Opening the DevTools triggers the "only-if-cached" request
+  // that cannot be handled by the worker. Bypass such requests.
+  if (request.cache === 'only-if-cached' && request.mode !== 'same-origin') {
+    return
+  }
+
+  // Bypass all requests when there are no active clients.
+  // Prevents the self-unregistered worked from handling requests
+  // after it's been deleted (still remains active until the next reload).
+  if (activeClientIds.size === 0) {
+    return
+  }
+
+  // Generate unique request ID.
+  const requestId = crypto.randomUUID()
+  event.respondWith(handleRequest(event, requestId))
+})
+
+async function handleRequest(event, requestId) {
+  const client = await resolveMainClient(event)
+  const response = await getResponse(event, client, requestId)
+
+  // Send back the response clone for the "response:*" life-cycle events.
+  // Ensure MSW is active and ready to handle the message, otherwise
+  // this message will pend indefinitely.
+  if (client && activeClientIds.has(client.id)) {
+    ;(async function () {
+      const responseClone = response.clone()
+
+      sendToClient(
+        client,
+        {
+          type: 'RESPONSE',
+          payload: {
+            requestId,
+            isMockedResponse: IS_MOCKED_RESPONSE in response,
+            type: responseClone.type,
+            status: responseClone.status,
+            statusText: responseClone.statusText,
+            body: responseClone.body,
+            headers: Object.fromEntries(responseClone.headers.entries()),
+          },
+        },
+        [responseClone.body],
+      )
+    })()
+  }
+
+  return response
+}
+
+// Resolve the main client for the given event.
+// Client that issues a request doesn't necessarily equal the client
+// that registered the worker. It's with the latter the worker should
+// communicate with during the response resolving phase.
+async function resolveMainClient(event) {
+  const client = await self.clients.get(event.clientId)
+
+  if (activeClientIds.has(event.clientId)) {
+    return client
+  }
+
+  if (client?.frameType === 'top-level') {
+    return client
+  }
+
+  const allClients = await self.clients.matchAll({
+    type: 'window',
+  })
+
+  return allClients
+    .filter((client) => {
+      // Get only those clients that are currently visible.
+      return client.visibilityState === 'visible'
+    })
+    .find((client) => {
+      // Find the client ID that's recorded in the
+      // set of clients that have registered the worker.
+      return activeClientIds.has(client.id)
+    })
+}
+
+async function getResponse(event, client, requestId) {
+  const { request } = event
+
+  // Clone the request because it might've been already used
+  // (i.e. its body has been read and sent to the client).
+  const requestClone = request.clone()
+
+  function passthrough() {
+    // Cast the request headers to a new Headers instance
+    // so the headers can be manipulated with.
+    const headers = new Headers(requestClone.headers)
+
+    // Remove the "accept" header value that marked this request as passthrough.
+    // This prevents request alteration and also keeps it compliant with the
+    // user-defined CORS policies.
+    const acceptHeader = headers.get('accept')
+    if (acceptHeader) {
+      const values = acceptHeader.split(',').map((value) => value.trim())
+      const filteredValues = values.filter(
+        (value) => value !== 'msw/passthrough',
+      )
+
+      if (filteredValues.length > 0) {
+        headers.set('accept', filteredValues.join(', '))
+      } else {
+        headers.delete('accept')
+      }
+    }
+
+    return fetch(requestClone, { headers })
+  }
+
+  // Bypass mocking when the client is not active.
+  if (!client) {
+    return passthrough()
+  }
+
+  // Bypass initial page load requests (i.e. static assets).
+  // The absence of the immediate/parent client in the map of the active clients
+  // means that MSW hasn't dispatched the "MOCK_ACTIVATE" event yet
+  // and is not ready to handle requests.
+  if (!activeClientIds.has(client.id)) {
+    return passthrough()
+  }
+
+  // Notify the client that a request has been intercepted.
+  const requestBuffer = await request.arrayBuffer()
+  const clientMessage = await sendToClient(
+    client,
+    {
+      type: 'REQUEST',
+      payload: {
+        id: requestId,
+        url: request.url,
+        mode: request.mode,
+        method: request.method,
+        headers: Object.fromEntries(request.headers.entries()),
+        cache: request.cache,
+        credentials: request.credentials,
+        destination: request.destination,
+        integrity: request.integrity,
+        redirect: request.redirect,
+        referrer: request.referrer,
+        referrerPolicy: request.referrerPolicy,
+        body: requestBuffer,
+        keepalive: request.keepalive,
+      },
+    },
+    [requestBuffer],
+  )
+
+  switch (clientMessage.type) {
+    case 'MOCK_RESPONSE': {
+      return respondWithMock(clientMessage.data)
+    }
+
+    case 'PASSTHROUGH': {
+      return passthrough()
+    }
+  }
+
+  return passthrough()
+}
+
+function sendToClient(client, message, transferrables = []) {
+  return new Promise((resolve, reject) => {
+    const channel = new MessageChannel()
+
+    channel.port1.onmessage = (event) => {
+      if (event.data && event.data.error) {
+        return reject(event.data.error)
+      }
+
+      resolve(event.data)
+    }
+
+    client.postMessage(
+      message,
+      [channel.port2].concat(transferrables.filter(Boolean)),
+    )
+  })
+}
+
+async function respondWithMock(response) {
+  // Setting response status code to 0 is a no-op.
+  // However, when responding with a "Response.error()", the produced Response
+  // instance will have status code set to 0. Since it's not possible to create
+  // a Response instance with status code 0, handle that use-case separately.
+  if (response.status === 0) {
+    return Response.error()
+  }
+
+  const mockedResponse = new Response(response.body, response)
+
+  Reflect.defineProperty(mockedResponse, IS_MOCKED_RESPONSE, {
+    value: true,
+    enumerable: true,
+  })
+
+  return mockedResponse
+}