Add Puppeteer testing (#166)

* Spike: add Puppeteer tests

Integrate Puppeteer tests into the existing Python Editor tests.

* Make tests more strict

* Restructure tests

- restructure tests so each test has its own -spec.js file
- start & stop local server after all tests
- remove device aspect of tests, and remove dependencies

* Reorganise tests; fix file paths

Neaten & fix tests by fixing test file paths.

* Move Puppeteer tests to a single file

Allows us to use a single browser object across all tests.

* No need to remove line

* Updates from feedback

- rearrange AAA
- remove dialogs from old hex tests
- clarify flags
- reduce dialog wait

* Use jQuery to get script name

* Get tests working in Azure

* Use 1.1.4 only in testing

* Split wait into ms

* Consistent quotes

* Move hex files to subdirectory, and minor tweaks.

Author: microbit-rosslowe

tests/jest.config.js

@@ -52,10 +52,10 @@ module.exports = {
   // forceCoverageMatch: [],
 
   // A path to a module which exports an async function that is triggered once before all test suites
-  // globalSetup: null,
+  globalSetup: "<rootDir>/run-server.js",
 
   // A path to a module which exports an async function that is triggered once after all test suites
-  // globalTeardown: null,
+  globalTeardown: "<rootDir>/stop-server.js",
 
   // A set of global variables that need to be available in all test environments
   // globals: {},