Started a greenfield e2e test framework

refs https://github.com/TryGhost/Toolbox/issues/129

- Having a fresh module should allow building new testing utility concepts from the ground up without being tied by the mystery baggage of the legacy localUtils/testUtils
- The outline of the concepts the framework will be handling is in the commont on the top of the e2e-framework file

test/regression/api/canary/admin/site.test.js

@@ -1,4 +1,5 @@
 const should = require('should');
+const framework = require('../../../../utils/e2e-framework');
 const testUtils = require('../../../../utils');
 const localUtils = require('./utils');
 const config = require('../../../../../core/shared/config');
@@ -7,7 +8,7 @@ describe('Config API', function () {
     let request;
 
     before(async function () {
-        request = await localUtils.getAuthenticatedAgent();
+        request = await framework.getAgent();
     });
 
     it('can retrieve config and all expected properties', async function () {

test/utils/e2e-framework.js

@@ -0,0 +1,36 @@
+// Set of common function that should be main building blocks for e2e tests.
+// The e2e tests usually consist of following building blocks:
+// - request agent
+// - state builder
+// - output state checker
+//
+// The request agetnt is responsible for making HTTP-like requests to an application (express app in case of Ghost).
+// Note there's no actual need to make an HTTP request to an actual server, bypassing HTTP and hooking into the application
+// directly is enough and reduces dependence on blocking a port (allows to run tests in parallel).
+//
+// The state builder is responsible for building the state of the application. Usually it's done by using pre-defined fixtures.
+// Can include building a DB state, file system state (themes, config files), building configuration state (config files) etc.
+//
+// The output state checker is responsible for checking the response from the app after performing a request.
+
+const supertest = require('supertest');
+
+const boot = require('../../core/boot');
+
+const startGhost = () => {
+    const defaults = {
+        backend: true,
+        frontend: false,
+        server: false
+    };
+
+    return boot(defaults);
+};
+
+const getAgent = async () => {
+    const app = await startGhost();
+
+    return supertest.agent(app);
+};
+
+module.exports.getAgent = getAgent;