Implement session state switch infrastructure required for DevExpress…

…/testcafe#243 (#1057)

package.json

@@ -1,7 +1,7 @@
 {
   "name": "testcafe-hammerhead",
   "description": "A powerful web-proxy used as a core for the TestCafe testing framework (https://github.com/DevExpress/testcafe).",
-  "version": "10.5.0",
+  "version": "10.6.0",
   "homepage": "https://github.com/DevExpress/testcafe-hammerhead",
   "bugs": {
     "url": "https://github.com/DevExpress/testcafe-hammerhead/issues"

src/request-pipeline/index.js

@@ -12,7 +12,11 @@ import { inject as injectUpload } from '../upload';
 // Stages
 var stages = {
     0: async function fetchProxyRequestBody (ctx, next) {
+        if (ctx.isPage && !ctx.isIframe)
+            ctx.session.onPageRequest();
+
         ctx.reqBody = await fetchBody(ctx.req);
+
         next();
     },
 

src/session/cookies.js

@@ -21,6 +21,16 @@ export default class Cookies {
         });
     }
 
+    serializeJar () {
+        return JSON.stringify(this.cookieJar.serializeSync());
+    }
+
+    setJar (serializedJar) {
+        this.cookieJar = serializedJar ?
+                         CookieJar.deserializeSync(JSON.parse(serializedJar)) :
+                         new CookieJar();
+    }
+
     setByServer (url, cookies) {
         this._set(url, cookies, false);
     }

src/session/index.js

@@ -23,7 +23,11 @@ export default class Session extends EventEmitter {
         this.proxy                 = null;
         this.externalProxySettings = null;
         this.pageLoadCount         = 0;
-        this.injectable            = {
+
+        this.requireStateSwitch   = false;
+        this.pendingStateSnapshot = null;
+
+        this.injectable = {
             scripts: ['/hammerhead.js'],
             styles:  []
         };
@@ -34,6 +38,19 @@ export default class Session extends EventEmitter {
         return shortId.generate();
     }
 
+    // State
+    getStateSnapshot () {
+        return this.cookies.serializeJar();
+    }
+
+    useStateSnapshot (snapshot) {
+        // NOTE: we don't perform state switch immediately, since there might be
+        // pending requests from current page. Therefore, we perform switch in
+        // onPageRequest handler when new page is requested.
+        this.requireStateSwitch   = true;
+        this.pendingStateSnapshot = snapshot;
+    }
+
     async handleServiceMessage (msg, serverInfo) {
         if (this[msg.cmd])
             return await this[msg.cmd](msg, serverInfo);
@@ -118,6 +135,14 @@ export default class Session extends EventEmitter {
         };
     }
 
+    onPageRequest () {
+        if (this.requireStateSwitch) {
+            this.cookies.setJar(this.pendingStateSnapshot);
+            this.requireStateSwitch   = false;
+            this.pendingStateSnapshot = null;
+        }
+    }
+
     _getIframePayloadScript (/* iframeWithoutSrc */) {
         throw new Error('Not implemented');
     }

test/server/proxy-test.js

@@ -94,8 +94,22 @@ describe('Proxy', function () {
             res.end();
         });
 
+        app.get('/cookie/set1', function (req, res) {
+            res.set('set-cookie', 'Set1_1=value1');
+            res.set('set-cookie', 'Set1_2=value2');
+
+            res.end();
+        });
+
+        app.get('/cookie/set2', function (req, res) {
+            res.set('set-cookie', 'Set2_1=value1');
+            res.set('set-cookie', 'Set2_2=value2');
+
+            res.end();
+        });
+
         app.get('/cookie/echo', function (req, res) {
-            res.end(req.headers['cookie']);
+            res.end('%% ' + req.headers['cookie'] + ' %%');
         });
 
         app.get('/page', function (req, res) {
@@ -466,7 +480,7 @@ describe('Proxy', function () {
             };
 
             request(options, function (err, res, body) {
-                expect(body).eql('Test=value; value without key');
+                expect(body).eql('%% Test=value; value without key %%');
                 done();
             });
         });
@@ -946,7 +960,7 @@ describe('Proxy', function () {
         });
     });
 
-    describe('file protocol', function () {
+    describe('file:// protocol', function () {
         var getFileProtocolUrl = function (filePath) {
             return path.resolve(__dirname, filePath).replace(/\\/g, '/');
         };
@@ -1031,6 +1045,122 @@ describe('Proxy', function () {
         });
     });
 
+    describe('State switching', function () {
+        function makeRequest (url, isResource) {
+            var options = {
+                url:     proxy.openSession(url, session),
+                headers: {}
+            };
+
+            if (!isResource)
+                options.headers['accept'] = 'text/html,application/xhtml+xml,application/xml;q=0.9,*!/!*;q=0.8';
+
+            return new Promise(function (resolve, reject) {
+                request(options, function (err, res, body) {
+                    if (err)
+                        reject(err);
+                    else
+                        resolve(body);
+                });
+            });
+        }
+
+        function forEachSequentially (arr, fn) {
+            return arr.reduce(function (promise, item) {
+                return promise.then(function () {
+                    return fn(item);
+                });
+            }, Promise.resolve());
+        }
+
+        it('Should switch states', function () {
+            var testCases = [
+                {
+                    state:    null,
+                    urls:     ['http://127.0.0.1:2000/cookie/set1'],
+                    expected: 'Set1_1=value1; Set1_2=value2'
+                },
+                {
+                    state:    null,
+                    urls:     ['http://127.0.0.1:2000/cookie/set2'],
+                    expected: 'Set2_1=value1; Set2_2=value2'
+                },
+                {
+                    state:    null,
+                    urls:     ['http://127.0.0.1:2000/cookie/set1', 'http://127.0.0.1:2000/cookie/set2'],
+                    expected: 'Set1_1=value1; Set1_2=value2; Set2_1=value1; Set2_2=value2'
+                }
+            ];
+
+            function initializeState (testCase) {
+                session.useStateSnapshot(null);
+
+                return forEachSequentially(testCase.urls, makeRequest).then(function () {
+                    testCase.state = session.getStateSnapshot();
+                });
+            }
+
+            function assertState (testCase) {
+                session.useStateSnapshot(testCase.state);
+
+                return makeRequest('http://127.0.0.1:2000/cookie/echo').then(function (body) {
+                    expect(body).contains('%% ' + testCase.expected + ' %%');
+                });
+            }
+
+            return Promise.resolve()
+                .then(function () {
+                    return forEachSequentially(testCases, initializeState);
+                })
+                .then(function () {
+                    return forEachSequentially(testCases, assertState);
+                });
+        });
+
+        it('Should switch state only on page requests', function () {
+            var state = null;
+
+            return makeRequest('http://127.0.0.1:2000/cookie/set1')
+                .then(function () {
+                    state = session.getStateSnapshot();
+
+                    session.useStateSnapshot(null);
+                })
+
+                // Try request empty state with non-page and page requests
+                .then(function () {
+                    return makeRequest('http://127.0.0.1:2000/cookie/echo', true);
+                })
+                .then(function (body) {
+                    expect(body).contains('%% Set1_1=value1; Set1_2=value2 %%');
+                })
+                .then(function () {
+                    return makeRequest('http://127.0.0.1:2000/cookie/echo', false);
+                })
+                .then(function (body) {
+                    expect(body).not.contains('%% Set1_1=value1; Set1_2=value2 %%');
+                })
+
+                .then(function () {
+                    session.useStateSnapshot(state);
+                })
+
+                // Try request Set1 state with non-page and page requests
+                .then(function () {
+                    return makeRequest('http://127.0.0.1:2000/cookie/echo', true);
+                })
+                .then(function (body) {
+                    expect(body).not.contains('%% Set1_1=value1; Set1_2=value2 %%');
+                })
+                .then(function () {
+                    return makeRequest('http://127.0.0.1:2000/cookie/echo', false);
+                })
+                .then(function (body) {
+                    expect(body).contains('%% Set1_1=value1; Set1_2=value2 %%');
+                });
+        });
+    });
+
     describe('Regression', function () {
         it('Should force "Origin" header for the same-domain requests (B234325)', function (done) {
             var options = {