How can I pass arg "--remote-debugging-port=9229" to VS Code Extension Host in launch.json?

Question

I want to lanuch VS Code with --remote-debugging-port.
I can do this with runTest.ts like below.
This works fine with puppereer.connect().

import { runTests } from '@vscode/test-electron';

async function main() {
  try {
    // The folder containing the Extension Manifest package.json
    // Passed to `--extensionDevelopmentPath`
    const extensionDevelopmentPath = path.resolve(__dirname, '../../');

    // The path to the extension test runner script
    // Passed to --extensionTestsPath
    const extensionTestsPath = path.resolve(__dirname, './suite/index');

    // Download VS Code, unzip it and run the integration test
    await runTests({ 
        extensionDevelopmentPath, 
        extensionTestsPath,
        launchArgs: [
            "--remote-debugging-port=9229",
        ]
    });
  } catch (err) {
    console.error(err);
    console.error('Failed to run tests');
    process.exit(1);
  }
}

main();

But when I try to do same thing with launch.json, it's failed.
When I start debug, this may cause FetchError: Failed to fetch browser webSocket URL from http://127.0.0.1:9229/json/version: request to http://127.0.0.1:9229/json/version failed, reason: connect ECONNREFUSED 127.0.0.1:9229

{
    "version": "0.2.0",
    "configurations": [
        {
            "name": "Run Extension Test",
            "type": "extensionHost",
            "request": "launch",
            "args": [
                "--extensionDevelopmentPath=${workspaceFolder}",
                "--extensionTestsPath=${workspaceFolder}/out/test/suite/index", 
            ],
            "runtimeArgs": [
                "--remote-debugging-port=9229",
],
            "outFiles": [
                "${workspaceFolder}/out/test/**/*.js"
            ],
            "preLaunchTask": "test-compile"
        },
    ]
}

How can I do this with launch.json?

Edit:
I update my launch.json and http://127.0.0.1:9229 is now opened.

{
"args": [
    "--remote-debugging-port=9229",
    "--extensionDevelopmentPath=${workspaceFolder}",
    "--extensionTestsPath=${workspaceFolder}/out/test/suite/index", 
            ],
"port": "9229",
}

But now, I dont get webSocketDebuggerUrl from result of fetch 127.0.0.1:9229. It only return this json.

{Browser: 'node.js/v14.16.0', Protocol-Version: '1.1'}

Answer 1

Looking at the code they have a specific location of the launchArgs

if runTests works you could try

{
    "version": "0.2.0",
    "configurations": [
        {
            "name": "Run Extension Test",
            "type": "extensionHost",
            "request": "launch",
            "args": [
                "--remote-debugging-port=9229",
                "--extensionDevelopmentPath=${workspaceFolder}",
                "--extensionTestsPath=${workspaceFolder}/out/test/suite/index", 
            ],
            "outFiles": [
                "${workspaceFolder}/out/test/**/*.js"
            ],
            "preLaunchTask": "test-compile"
        },
    ]
}