Cypress 10. Plugin events - cannot add more than one listener to events

[kpturner]

I have found since using Cypress 10 that if I have multiple listeners on, for example before:browser:launch then only the last listener added fires. For example, if I do this

on('before:browser:launch', (browser, launchOptions) => {
    console.log('FIRST');
});
on('before:browser:launch', (browser, launchOptions) => {
    console.log(SECOND');
});
on('before:browser:launch', (browser, launchOptions) => {
    console.log('THIRD');
});

Then only THIRD gets logged.

This has meant that various plugins that have functions listening to before:browser:launch have simply stopped working as expected. The only one that works is the last one to add a listener to the event.

Is this a bug or by design?

[lmiller1990]

This sounds like a bug to me - we should be merging all the listeners together, so multiple plugins can use the same hook.

I wonder if it's getting clobbered here: https://github.com/cypress-io/cypress/blob/develop/packages/data-context/src/data/EventRegistrar.ts#L40

I think we should open an issue, sounds like a bug.

[kpturner]

Please see #23496