Add from_senders for the Sync Client

[BKDaugherty]

A lot of my team's code uses the synchronous client. I'd like to be able to easily write tests using a Fake Mqtt client. One easy way to do this for unit tests is by using something like the from_senders method that's available on the AsyncClient. This PR adds a from_sender method for the sync client which can be used to write tests like the one I wrote in this PR.

It also updates a stale comment on the async client.

Type of change

New feature (non-breaking change which adds functionality)

Checklist:

• Formatted with cargo fmt
• Make an entry to CHANGELOG.md if it's relevant to the users of the library. If it's not relevant mention why.

[swanandx]

Thanks for the PR and your patience!

Can you please add the same changes for v5/client as well? so we can stay consistent!

[BKDaugherty]

Yeah absolutely!

[swanandx]

any updates @BKDaugherty ?

[BKDaugherty]

any updates @BKDaugherty ?

Hey! Sorry @swanandx, I was AFK a bit for the holidays. Just updated to add this to the v5 client as well! Is there a proposal at all for unifying these? Would be curious to see that

[BKDaugherty]

Hm. Any idea why the macos tests would fail? Doesn't seem related to this

[swanandx]

I was AFK a bit for the holidays. Just updated to add this to the v5 client as well!

Oh no worries, Thank you so much!

Is there a proposal at all for unifying these? Would be curious to see that

I was thinking about it, but then how would be distinguish between v4 & v5 clients? we might need to store a field like protocol in client and choose publish / subscribe based on it, otherwise introduce generics or something. I thought it might add much more complexity, if you think that isn't the case, feel free to open a RFC, would definitely love to see it :)

Hm. Any idea why the macos tests would fail? Doesn't seem related to this

i don't have that idea either haha, it keeps failing randomly. so we can ignore it