isup: fix double output, and add tests

[dgw]

Description

Fixes #2061, a regression introduced in 5af0eea.

Checklist

• I have read CONTRIBUTING.md
• I can and do license this contribution under the EFLv2
• No issues are reported by make qa (runs make quality and make test)
• I have tested the functionality of the things this change touches

[Exirel]

I think it would be better to use else:

try:
    # do something
except:
    # bot.reply error
except:
    # bot.reply a different error
else:
    # bot.say all is fine

[dgw]

@Exirel Yeah, per our IRC chatter I did that locally. Haven't pushed yet; sparing Travis until I finish writing the test suite.

[Exirel]

Is it possible to refactor mocks to reduce the duplicate code in tests? Yes, for sure. Is it necessary to approve that PR? No, it's fine like it is.

Well done on your testing journey, I hope it was enjoyable. As discussed, some tweaks are required in the future to make it even easier, and I probably need to write some more doc about it.

For now, this is a go!

[dgw]

@Exirel Reimplemented fixtures, along with a much more interesting use of bot.running_triggers that I think you'll appreciate:

sopel/sopel/bot.py

Lines 959 to 962 in 559987d

	We want to keep track of running triggers, mostly for testing and
	debugging purposes. For instance, it'll help make sure, in tests, that
	a bot plugin has finished processing a trigger, by manually joining
	all running threads.

Early in the process, before figuring out that threading was the problem, I wrongly theorized that some multiple-instance voodoo might be messing up which bot (or at the time, mockbot) got the message vs. which one I checked for message_sent. Since my goal was to get one test working before writing the rest based on it, I removed the fixtures just in case. Clearly, it wasn't necessary, but at the time it seemed like eliminating as many pseudo-magical bits of pytest as possible would help me track down why a seemingly innocuous example directly from one of your own docstrings simply refused to work. 😅

[Exirel]

Even better now!