Do not send requests for SNI server through upstream proxy (#4275)

* add test to ensure that SNI server will never go through proxy

* prevent test from false positive

* ensure that SNI server requests never go through proxy

* e2e test that https-proxy does not pass sni reqs thru upstream

* improve debug logging in https-proxy

* fix using cwd, not workspaceFolder for terminals manager

* remove dead code

* stop the debug proxy after each test


Co-authored-by: Brian Mann <brian.mann86@gmail.com>

packages/https-proxy/test/integration/proxy_spec.coffee

@@ -5,6 +5,7 @@ process.env.NODE_TLS_REJECT_UNAUTHORIZED = "0"
 _           = require("lodash")
 DebugProxy  = require("@cypress/debugging-proxy")
 net         = require("net")
+network     = require("@packages/network")
 path        = require("path")
 Promise     = require("bluebird")
 proxy       = require("../helpers/proxy")
@@ -241,6 +242,27 @@ describe "Proxy", ->
             expect(socket.destroyed).to.be.true
             resolve()
 
+    ## https://github.com/cypress-io/cypress/issues/4257
+    it "passes through to SNI when it is intercepted and not through proxy", ->
+      createSocket = @sandbox.stub(network.connect, 'createRetryingSocket').callsArgWith(1, new Error('stub'))
+      createProxyConn = @sandbox.spy(network.agent.httpsAgent, 'createUpstreamProxyConnection')
+
+      request({
+        strictSSL: false
+        url: "https://localhost:8443"
+        proxy: "http://localhost:3333"
+        resolveWithFullResponse: true
+        forever: false
+      })
+      .then =>
+        throw new Error('should not succeed')
+      .catch { message: 'Error: socket hang up' }, =>
+        expect(createProxyConn).to.not.be.called
+        expect(createSocket).to.be.calledWith({
+          port: @proxy._sniPort
+          host: 'localhost'
+        })
+
     afterEach ->
       @upstream.stop()
       delete process.env.HTTP_PROXY

packages/https-proxy/test/spec_helper.coffee

@@ -5,6 +5,7 @@ sinonChai     = require("sinon-chai")
 sinonPromise  = require("sinon-as-promised")(Promise)
 
 global.request   = require("request-promise")
+global.sinon     = sinon
 global.supertest = require("supertest")
 
 chai.use(sinonChai)
@@ -15,4 +16,4 @@ beforeEach ->
   @sandbox = sinon.sandbox.create()
 
 afterEach ->
-  @sandbox.restore()
+  @sandbox.restore()