[BUG] Native C++ Callback does not work when running Electron App with Node Add-on using Playwright

[anvosoughi]

Context:

• Playwright Version: 1.19.2
• Operating System: Windows 10
• Node.js version: 16.14.0
• Electron: 17.1.0
• Node Add-on: build with Electron "17.1.0" and "node-addon-api": "^4.3.0"

Bug Repository

https://github.com/anvosoughi/playwright-electron-node-addon-sample

Electron Code:

https://github.com/anvosoughi/playwright-electron-node-addon-sample/blob/main/electron/main.js

Playwright Code

https://github.com/anvosoughi/playwright-electron-node-addon-sample/blob/main/e2e/specs/home.spec.ts

Describe the bug

I have a simple Electron sample app, which uses the 'node-addon-api' to make a call from JavaScript(electron app) to C++ add-on, and receive a callback from C++ add-on to the JavaScript(electron app).

When the app is launched, the triggerCallback function is automatically executed, which triggers C++ add-on to make one call to the app every second using a callback.

There is a console output of "triggerCallback fired" when the function is executed. And "callback result: XX" is printed to console every second thereafter.

This works well when launching the app without Playwright

But when we use Playwright to launch the app, the function is executed as expected, but the call back does not fire.

Note:

You can also trigger the callback manually using the button with text "Trigger Callback"

This app is for Windows OS only

[yury-s]

I cannot reproduce it on Linux, with modified preload.js:

const loadLib = () => {
  if (PLATFORM === "win32") {
    return require(`./libs/Test_Module_Windows.node`);
  }

  return require(`./libs/Test_Module_Linux.node`);
};

and it worked well:

Perhaps the library path doesn't work well on Windows?

[anvosoughi]

@yury-s thanks for taking a look. But the issue we have is only when launching the app with Playwright, and only on Windows.

Can you confirm if you tested with running app with Playwright? ie. "npm run test:e2e" ?

Also not sure what you mean by wrong path? because the app works without Playwright...

[yury-s]

Can you confirm if you tested with running app with Playwright? ie. "npm run test:e2e" ?

Yes, this is how I launched it. I tested it only on linux though.

Also not sure what you mean by wrong path? because the app works without Playwright...

If it works without playwright it rules out my hypothesis. Can you add debug logging to see if "return require(./libs/Test_Module_Windows.node);" runs without errors? I'd also suggest you run with DEBUG=pw:browser environment variable to see the browser output, it may give you a hint.

[anvosoughi]

@yury-s Here is the output with pw:browser and pw:api. Nothing stands out to me. Although everything passes, the call backs are still not working when looking at the console output, and this is again only when launching app through Playwright.

pw:api

pw:browser

[yury-s]

The output looks normal. One difference is that I ran the test with npm but I don't think it matters. It looks like helloWorld.testModule.trigger_callback(); is executed well (there is no exception in the console), did you try inserting logs into the native module to see where the execution stalls? It's hard to tell why the code is not triggered properly under playwright, playwright just starts electron as a regular binary, compared to manual run we just pass the --inspect=0 --remote-debugging-port=0 command line arguments.

[anvosoughi]

@yury-s

I updated my "start" command to be "electron ./electron/main.js --inspect=0 --remote-debugging-port=0"

I added lots of logs in the native module. I found two differences between using Playwright and not.

What I found was that require() is only called once as expected on JS side, but on native, the node thread calls load_API() 2 times when running with Playwright. But only once without Playwright, when we use "start" command.

When using Playwright, after we call NonBlockingCall() in our native thread, the JS callback "javascript_callback()" is not fired....
But is called a single time at the very end of the log, when the app is being shutdown...
When not using Playwright, after we call NonBlockingCall() in our native thread, the JS callback "javascript_callback()" is fired every second as expected

The log files for attached for both scenarios:
native-electron.log
native-playwright.log

[pavelfeldman]

Electron support is still experimental in Playwright, so we are not prioritizing it. If you nail down the bug and have a fix, we'll be happy to review and accept it.

[pavelfeldman]

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