cy.screenshot not respecting the viewport size on Firefox.

[aayknija]

Using: Cypress package version: 6.6.0, OS-Windows 10 , Firefox -86.0.1 (64-bit)

As per the documentation, I have added the below code snippet in plugins/index.js still it is not working as expected. The expectation is to take the screenshot in provided resolution.

Command: cypress run --browser firefox --headless

on('before:browser:launch', (browser = {}, launchOptions) => {
    if (browser.name === 'firefox') {
      launchOptions.args.push('--width=1680');
      launchOptions.args.push('--height=1024');
      return launchOptions;
    }
  });

P.S: It works perfectly on chrome with the below code snippet in plugins/index.js

on('before:browser:launch', (browser = {}, launchOptions) => {
   if (browser.name === 'chrome') {
     launchOptions.args.push('--disable-dev-shm-usage');
     launchOptions.args.push('--window-size=1680,1024');
     launchOptions.args.push('--disable-gpu');
     return launchOptions;
   }
 });

I tried adding --disable-dev-shm-usage and --disable-gpu for firefox also but it did not work.

[kuceb]

@aayknija can you provide what screenshot size you're seeing with those options in firefox? It's possible the window size for firefox includes the ~74 pixels of titlebar/menu, so the screenshots may be 1680x950. If that's the case you can try adding 74px to the height argument. We haven't normalized this for users since it's unclear how stable it would be.

   if (browser.name === 'firefox') {
      launchOptions.args.push('--width=1680');
      launchOptions.args.push('--height=1098');
      return launchOptions;
    }

[aayknija]

@bkucera Apologies for the delayed response. I did try the above option as well. The issue was it was not respecting the width and height provided in launch options. I was getting an image with a resolution of 1680x950 and size did vary in the docker image.

Finally, after some google search, I found one solution where I have to define MOZ_HEADLESS_WIDTH and MOZ_HEADLESS_HEIGHT in the environment variable and that worked for me.

[cypress-bot]

The code for this is done in cypress-io/cypress#15686, but has yet to be released.
We'll update this issue and reference the changelog when it's released.

[bahmutov]

Released in v7.0.0