fix cypress-in-cypress tests for chrome 119 and up

packages/proxy/lib/http/response-middleware.ts

@@ -345,6 +345,27 @@ const OmitProblematicHeaders: ResponseMiddleware = function () {
   this.next()
 }
 
+const MaybeSetOriginAgentClusterHeader: ResponseMiddleware = function () {
+  if (process.env.CYPRESS_INTERNAL_E2E_TESTING_SELF_PARENT_PROJECT) {
+    const origin = new URL(this.req.proxiedUrl).origin
+
+    if (process.env.HTTP_PROXY_TARGET_FOR_ORIGIN_REQUESTS && process.env.HTTP_PROXY_TARGET_FOR_ORIGIN_REQUESTS === origin) {
+      // For cypress-in-cypress tests exclusively, we need to bucket all origin-agent-cluster requests
+      // from HTTP_PROXY_TARGET_FOR_ORIGIN_REQUESTS to include Origin-Agent-Cluster=false. This has to due with changed
+      // behavior starting in Chrome 119. The new behavior works like the following:
+      //     If a page did not request an origin-keyed agent cluster, chrome will place it in one
+      //     anyway because a previous request went through without the Origin-Agent-Cluster=false header set.
+      //     At time of writing, documentation detailing this behavior has not been found.
+
+      // To work around this, any request that matches the origin of HTTP_PROXY_TARGET_FOR_ORIGIN_REQUESTS
+      // should set the Origin-Agent-Cluster=false header to avoid origin-keyed agent clusters for
+      this.res.setHeader('Origin-Agent-Cluster', '?0')
+    }
+  }
+
+  this.next()
+}
+
 const SetInjectionLevel: ResponseMiddleware = function () {
   const span = telemetry.startSpan({ name: 'set:injection:level', parentSpan: this.resMiddlewareSpan, isVerbose })
 
@@ -933,6 +954,7 @@ export default {
   InterceptResponse,
   PatchExpressSetHeader,
   OmitProblematicHeaders, // Since we might modify CSP headers, this middleware needs to come BEFORE SetInjectionLevel
+  MaybeSetOriginAgentClusterHeader, // NOTE: only used in cypress-in-cypress testing. this is otherwise a no-op
   SetInjectionLevel,
   MaybePreventCaching,
   MaybeStripDocumentDomainFeaturePolicy,

packages/proxy/test/unit/http/response-middleware.spec.ts

@@ -19,6 +19,7 @@ describe('http/response-middleware', function () {
       'InterceptResponse',
       'PatchExpressSetHeader',
       'OmitProblematicHeaders',
+      'MaybeSetOriginAgentClusterHeader',
       'SetInjectionLevel',
       'MaybePreventCaching',
       'MaybeStripDocumentDomainFeaturePolicy',
@@ -448,6 +449,65 @@ describe('http/response-middleware', function () {
     }
   })
 
+  describe('MaybeSetOriginAgentClusterHeader', function () {
+    const { MaybeSetOriginAgentClusterHeader } = ResponseMiddleware
+
+    let CYPRESS_INTERNAL_E2E_TESTING_SELF_PARENT_PROJECT
+    let PREVIOUS_HTTP_PROXY_TARGET_FOR_ORIGIN_REQUESTS
+    let ctx
+
+    beforeEach(function () {
+      CYPRESS_INTERNAL_E2E_TESTING_SELF_PARENT_PROJECT = process.env.CYPRESS_INTERNAL_E2E_TESTING_SELF_PARENT_PROJECT
+      PREVIOUS_HTTP_PROXY_TARGET_FOR_ORIGIN_REQUESTS = process.env.HTTP_PROXY_TARGET_FOR_ORIGIN_REQUESTS
+      ctx = {
+        req: {
+          proxiedUrl: 'http://localhost:4455',
+        },
+        res: {
+          setHeader: sinon.stub(),
+          on: (event, listener) => {},
+          off: (event, listener) => {},
+        },
+      }
+    })
+
+    this.afterEach(function () {
+      beforeEach(function () {
+        process.env.CYPRESS_INTERNAL_E2E_TESTING_SELF_PARENT_PROJECT = CYPRESS_INTERNAL_E2E_TESTING_SELF_PARENT_PROJECT
+        process.env.HTTP_PROXY_TARGET_FOR_ORIGIN_REQUESTS = PREVIOUS_HTTP_PROXY_TARGET_FOR_ORIGIN_REQUESTS
+      })
+    })
+
+    it('doesn\'t set the Origin-Agent-Cluster for the request if cypress-in-cypress testing is off', function () {
+      delete process.env.CYPRESS_INTERNAL_E2E_TESTING_SELF_PARENT_PROJECT
+
+      return testMiddleware([MaybeSetOriginAgentClusterHeader], ctx)
+      .then(() => {
+        expect(ctx.res.setHeader).not.to.be.called
+      })
+    })
+
+    it('doesn\'t set the Origin-Agent-Cluster for the request if cypress-in-cypress testing is on but url does NOT match http proxy', function () {
+      process.env.CYPRESS_INTERNAL_E2E_TESTING_SELF_PARENT_PROJECT = '1'
+      process.env.HTTP_PROXY_TARGET_FOR_ORIGIN_REQUESTS = 'http://localhost:4456'
+
+      return testMiddleware([MaybeSetOriginAgentClusterHeader], ctx)
+      .then(() => {
+        expect(ctx.res.setHeader).not.to.be.called
+      })
+    })
+
+    it('sets the Origin-Agent-Cluster for the request if cypress-in-cypress testing is on and url matches http proxy', function () {
+      process.env.CYPRESS_INTERNAL_E2E_TESTING_SELF_PARENT_PROJECT = '1'
+      process.env.HTTP_PROXY_TARGET_FOR_ORIGIN_REQUESTS = 'http://localhost:4455'
+
+      return testMiddleware([MaybeSetOriginAgentClusterHeader], ctx)
+      .then(() => {
+        expect(ctx.res.setHeader).to.be.calledWith('Origin-Agent-Cluster', '?0')
+      })
+    })
+  })
+
   describe('SetInjectionLevel', function () {
     const { SetInjectionLevel } = ResponseMiddleware
     let ctx