fix(nextjs): Fix nock wrapping conflict in integration tests

packages/nextjs/test/integration/test/server/tracingHttp.js

@@ -40,7 +40,10 @@ module.exports = async ({ url: urlBase, argv }) => {
     'tracingHttp',
   );
 
-  await getAsync(url);
+  // The `true` causes `getAsync` to rewrap `http.get` in next 12, since it will have been overwritten by the import of
+  // `nock` above. See https://github.com/getsentry/sentry-javascript/pull/4619.
+  // TODO: see note in `getAsync` about removing the boolean
+  await getAsync(url, true);
   await sleep(250);
 
   assert.ok(capturedRequest.isDone(), 'Did not intercept expected request');

packages/nextjs/test/integration/test/utils/server.js

@@ -1,12 +1,22 @@
 const { get } = require('http');
 const nock = require('nock');
+const nodeSDK = require('@sentry/node');
 const { logIf, parseEnvelope } = require('./common');
 
 Error.stackTraceLimit = Infinity;
 
-const getAsync = url => {
+const getAsync = (url, rewrap = false) => {
+  // Depending on what version of Nextjs we're testing, the wrapping which happens in the `Http` integration may have
+  // happened too early and gotten overwritten by `nock`. This redoes the wrapping if so.
+  //
+  // TODO: This works but is pretty hacky in that it has the potential to wrap things multiple times, more even than the
+  // double-wrapping which is discussed at length in the comment in `ensureWrappedGet` below, which is why we need
+  // `rewrap`. Once we fix `fill` to not wrap things twice, we should be able to take this out and just always call
+  // `ensureWrappedGet`.
+  const wrappedGet = rewrap ? ensureWrappedGet(get, url) : get;
+
   return new Promise((resolve, reject) => {
-    get(url, res => {
+    wrappedGet(url, res => {
       res.setEncoding('utf8');
       let rawData = '';
       res.on('data', chunk => {
@@ -99,6 +109,60 @@ const objectMatches = (actual, expected) => {
   return true;
 };
 
+/**
+ * Rewrap `http.get` if the wrapped version has been overridden by `nock`.
+ *
+ * This is only relevant for Nextjs >= 12.1, which changed when `_app` is initialized, which in turn changed the order
+ * in which our SDK and `nock` wrap `http.get`. See https://github.com/getsentry/sentry-javascript/pull/4619.
+ *
+ * TODO: We'll have to do this for `ClientRequest` also if we decide to start wrapping that.
+ * TODO: Can we fix the wrapping-things-twice problem discussed in the comment below?
+ */
+function ensureWrappedGet(importedGet, url) {
+  // we always test against the latest minor for any given Nextjs major version, so if we're testing Next 12, it's
+  // definitely at least 12.1, making this check against the major version sufficient
+  if (Number(process.env.NEXTJS_VERSION) < 12) {
+    return importedGet;
+  }
+
+  // As of Next 12.1, creating a `NextServer` instance (which we do immediately upon starting this test runner) loads
+  // `_app`, which has the effect of initializing the SDK. So, unless something's gone wrong, we should always be able
+  // to find the integration
+  let httpIntegration;
+  try {
+    httpIntegration = nodeSDK.getCurrentHub().getClient().getIntegration(nodeSDK.Integrations.Http);
+  } catch (err) {
+    console.warn(`Warning: Sentry SDK not set up at \`NextServer\` initialization. Request URL: ${url}`);
+    return importedGet;
+  }
+
+  // This rewraps `http.get` and `http.request`, which, at this point, look like `nockWrapper(sentryWrapper(get))` and
+  // `nockWrapper(sentryWrapper(request))`. By the time we're done with this function, they'll look like
+  // `sentryWrapper(nockWrapper(sentryWrapper(get)))` and `sentryWrapper(nockWrapper(sentryWrapper(request)))`,
+  // respectively. Though this seems less than ideal, we don't have to worry about our instrumentation being
+  // (meaningfully) called twice because:
+  //
+  // 1) As long as we set up a `nock` interceptor for any outgoing http request, `nock`'s wrapper will call a replacement
+  //    function for that request rather than call the function it's wrapping (in other words, it will look more like
+  //    `sentryWrapper(nockWrapper(getSubstitute))` than `sentryWrapper(nockWrapper(sentryWrapper(get)))`), which means
+  //    our code is only called once.
+  // 2) In cases where we don't set up an interceptor (such as for the `wrappedGet` call in `getAsync` above), it's true
+  //    that we can end up with `sentryWrapper(nockWrapper(sentryWrapper(get)))`, meaning our wrapper code will run
+  //    twice. For now that's okay because in those cases we're not in the middle of a transactoin and therefore
+  //    the two wrappers' respective attempts to start spans will both no-op.
+  //
+  // TL; DR - if the double-wrapping means you're seeing two spans where you really only want one, set up a nock
+  // interceptor for the request.
+  //
+  // TODO: add in a "don't do this twice" check (in `fill`, maybe moved from `wrap`), so that we don't wrap the outer
+  // wrapper with a third wrapper
+  httpIntegration.setupOnce();
+
+  // now that we've rewrapped it, grab the correct version of `get` for use in our tests
+  const httpModule = require('http');
+  return httpModule.get;
+}
+
 module.exports = {
   getAsync,
   interceptEventRequest,

packages/nextjs/test/run-integration-tests.sh

@@ -32,6 +32,11 @@ mv next.config.js next.config.js.bak
 
 for NEXTJS_VERSION in 10 11 12; do
 
+  # export this to the env so that we can behave differently depending on which version of next we're testing, without
+  # having to pass this value from function to function to function to the one spot, deep in some callstack, where we
+  # actually need it
+  export NEXTJS_VERSION=$NEXTJS_VERSION
+
   # Next 10 requires at least Node v10
   if [ "$NODE_MAJOR" -lt "10" ]; then
     echo "[nextjs] Next.js is not compatible with versions of Node older than v10. Current version $NODE_VERSION"