Add Accounts.onLogout(func) Hook

[pmoons]

Accounts.onLogout(func) is practically identical to the implementation of Accounts.onLogin(func). This PR is an effort to maintain symmetry between the available Login / Logout hooks.

Use cases include destroying active session variables, reverting UI elements, and any other cleanup that needs to occur immediately after the user is logged out.

This PR is related to the following discussions:
#5984
#3867

#1074
#426

Corresponding user-facing documentation has also been provided in this PR, as well as appropriate tests.

[pmoons]

Test failed in livedata package. Could someone help me discover the issue on this please? Only did work in accounts-base package.

Failed Test:

tinytest - livedata stub - reconnect non-idempotent method : !!!!!!!!! FAIL !!!!!!!!!!!
{"groupPath":["tinytest","livedata stub"],"test":"reconnect non-idempotent method","events":[{"sequence":2489,"type":"fail","details":{"type":"true","not":false},"cookie":{"name":"livedata stub - reconnect non-idempotent method","offset":0,"groupPath":["tinytest","livedata stub"],"shortName":"reconnect non-idempotent method"}}]}

EDIT It seems that checking out commit 7012957a still has the same failing test. My guess is that this issue is not related and outside the scope of this PR.

[jremi]

This feature is very important. Thank you for working on this, hopefully this onLogout hook will be available soon.

[tmeasday]

Can you rebase this to be off of current devel? I think this branch is off an earlier commit with failing self tests. It should be as easy as (assuming you have a remote called upstream pointing here):

# optionally
git remote add upstream https://github.com/meteor/meteor

git fetch upstream
git rebase upstream/devel
git push --force

Also, note that the docs have moved to https://github.com/meteor/docs. Sorry this PR got caught up in that change, so for now just remove the docs changes from the PR and we'll open a PR there once this commit is in.

[jdmswong]

add this!!

[tmeasday]

@pmoons?

[Ben305]

This would be great 👍

[benjamn]

Shouldn't this be an array ([])?

[tmeasday]

Ok, I rebased and squashed some commits (and addressed @benjamn's comment) here: #7187

[convexset]

Seems to be a major asymmetry here. Accounts.onLogin callbacks are called with an object argument with "signature" {type, allowed, methodName, methodArguments, user, connection}, and Accounts.onLogout callbacks are called with no arguments, and with no special function invocation context (i.e.: this)...

The relevant connection id has to be scrounged up with DDP._CurrentInvocation.getOrNullIfOutsideFiber(), which strikes me as... excessive. Whyyyyyyyyyyyyy?

At the very least, the userId of the user logging out, and current connection should be provided....

[tmeasday]

@convexset #7433 should be released in 1.4.1 soon.

[interfaith]

is onLogout available ?
after logging in with Twitter
a way to clean up before logging out is VITAL !!