How to use `--use-file-for-fake-video-capture` with `cypress run`

What would you like?

https://docs.cypress.io/api/plugins/browser-launch-api#Use-fake-video-for-webcam-testing I followed the docs to override default video input to test my app, it works well with Chrome but not with Electron.

To be exact, I test with a .mjpeg file like so

cypress/plugins/index.ts

/// <reference types="cypress" />
// ***********************************************************
// This example plugins/index.js can be used to load plugins
//
// You can change the location of this file or turn off loading
// the plugins file with the 'pluginsFile' configuration option.
//
// You can read more here:
// https://on.cypress.io/plugins-guide
// ***********************************************************

// This function is called when a project is opened or re-opened (e.g. due to
// the project's config changing)

/**
 * @type {Cypress.PluginConfig}
 */
module.exports = (
  on: Cypress.PluginEvents,
  config: Cypress.PluginConfigOptions
) => {
  // `on` is used to hook into various events Cypress emits
  // `config` is the resolved Cypress config
  on(
    'before:browser:launch',
    (
       browser = {
        name: '',
        family: 'chromium',
        channel: '',
        displayName: '',
        version: '',
        majorVersion: '',
        path: '',
        isHeaded: false,
        isHeadless: false,
      },
      launchOptions
    ) => {
      if (browser.family === 'chromium') {
        launchOptions.args.push(
          '--use-file-for-fake-video-capture=cypress/fixtures/assets/fake-video.mjpeg'
        );
      }

      return launchOptions;
    }
  );

  return config;
};

The supplied video is still this green pie chart, does Electron need extra config steps ?

It seems that Electron supports this feature so I’m curious about why it’s not working out of the box https://github.com/electron/electron/issues/4505

Why is this needed?

I need to test video upload both locally and in CI and it currently only works with cypress open not cypress run

Other

No response

[mjhenkes]

I’m going to close this issue for now, We appear to be passing the flag correctly to electron, but electron doesn’t appear to honor it.

[mjhenkes]

Based on the issue you linked, it seems like --use-file-for-fake-video-capture should work in electron but it definitely doesn’t. It seems like it is an electron issue? We do pass the flag to electron, but it doesn’t seem to honor it.