feat: expose frame's execution contexts (#3048)

This patch exposes frame's execution contexts, making it possible
to debug extension's content scripts.

This is a resurrected #2812.

test/assets/simple-extension/content-script.js

@@ -0,0 +1,3 @@
+console.log('hey from the content-script');
+self.thisIsTheContentScript = true;
+

test/assets/simple-extension/manifest.json

@@ -1,12 +1,14 @@
 {
   "name": "Simple extension",
   "version": "0.1",
-  "app": {
-    "background": {
-      "scripts": ["index.js"]
-    }
+  "background": {
+    "scripts": ["index.js"]
   },
-  "permissions": ["background"],
-  
+  "content_scripts": [{
+    "matches": ["<all_urls>"],
+    "css": [],
+    "js": ["content-script.js"]
+  }],
+  "permissions": ["background", "activeTab"],
   "manifest_version": 2
 }

test/headful.spec.js

@@ -16,6 +16,7 @@
 
 const path = require('path');
 const os = require('os');
+const {waitEvent} = require('./utils.js');
 
 const TMP_FOLDER = path.join(os.tmpdir(), 'pptr_tmp_folder-');
 
@@ -115,6 +116,27 @@ module.exports.addTests = function({testRunner, expect, PROJECT_ROOT, defaultBro
       ]);
       await browser.close();
     });
+    it('should report content script execution contexts', async({server}) => {
+      const browserWithExtension = await puppeteer.launch(extensionOptions);
+      const page = await browserWithExtension.newPage();
+      const [extensionContext, msg] = await Promise.all([
+        waitEvent(page, 'executioncontextcreated', context => !context.isDefault()),
+        waitEvent(page, 'console'),
+        page.goto(server.EMPTY_PAGE)
+      ]);
+      expect(msg.text()).toBe('hey from the content-script');
+      expect(page.mainFrame().executionContexts().length).toBe(2);
+      expect(extensionContext.frame()).toBe(page.mainFrame());
+      expect(extensionContext.name()).toBe('Simple extension');
+      expect(await extensionContext.evaluate('thisIsTheContentScript')).toBe(true);
+
+      const [destroyedContext] = await Promise.all([
+        waitEvent(page, 'executioncontextdestroyed', context => !context.isDefault()),
+        page.reload()
+      ]);
+      expect(destroyedContext).toBe(extensionContext);
+      await browserWithExtension.close();
+    });
   });
 };
 

test/page.spec.js

@@ -77,6 +77,11 @@ module.exports.addTests = function({testRunner, expect, puppeteer, DeviceDescrip
       const result = await page.evaluate(() => 7 * 3);
       expect(result).toBe(21);
     });
+    it('should have nice default execution context', async({page, server}) => {
+      const executionContext = await page.mainFrame().executionContext();
+      expect(executionContext.name()).toBe('');
+      expect(executionContext.isDefault()).toBe(true);
+    });
     it('should throw when evaluation triggers reload', async({page, server}) => {
       let error = null;
       await page.evaluate(() => {

test/utils.js

@@ -78,7 +78,14 @@ const utils = module.exports = {
    * @param {string} eventName
    * @return {!Promise<!Object>}
    */
-  waitEvent: function(emitter, eventName) {
-    return new Promise(fulfill => emitter.once(eventName, fulfill));
+  waitEvent: function(emitter, eventName, predicate = () => true) {
+    return new Promise(fulfill => {
+      emitter.on(eventName, function listener(event) {
+        if (!predicate(event))
+          return;
+        emitter.removeListener(eventName, listener);
+        fulfill(event);
+      });
+    });
   },
 };