ReactionMessage item_user property should be marked as optional (Incoming Webhooks)

[y-i]

Description

hubot-slack can't react to reaction_added events if the message which reaction was added to is incoming webhook.

What type of issue is this? (place an x in one of the [ ])

• bug
• enhancement (feature request)
• question
• documentation related
• testing related
• discussion

Requirements (place an x in each of the [ ])

• I've read and understood the Contributing guidelines and have done my best effort to follow them.
• I've read and agree to the Code of Conduct.
• I've searched for any related issues and avoided creating a duplicate issue.

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Bug Report

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Reproducible in:

hubot-slack version: 4.4.0

node version: v8.9.4

OS version(s): macOS Sierra (10.12.6)

Steps to reproduce:

1. Join the bot which uses robot.react() to a channel.
2. Send a incoming webhook message to the channel.
3. Add reaction to the message.

Expected result:

robot.react() will be triggered.

Actual result:

robot.react() will not be triggered.

Attachments:

At this point, item_user is undefined in message if the message was posted by incoming webhook.
I can react to messages which were posted by incoming hook by changing return unless user && item_user to return unless user.

[aoberoi]

thanks for the report! this might be fixed in #465, because the code path changes significantly.

@y-i by any chance, is the user reacting to the incoming webhook message not a member of the local workspace? specifically, is this occurring in a shared channel?

@shanedewael do we have any tests that will cover this scenario? i don't think its specific to Incoming Webhook, but we should try.

[y-i]

@aoberoi I didn't use a shared channel. So the user is a member of the local workspace.

[aoberoi]

@y-i thanks, i was able to reproduce this (both on RTM and on Events API)

it turns out that this is expected (but not well documented) behavior. when the message is generated from an Incoming Webhook, there actually is no "user" responsible for sending it, so there's no item_user value at all.

we'll be updating the following documentation page to more clearly describe this: https://api.slack.com/events/reaction_added

in the meantime, i think we can more clearly mark the property as optional here:

hubot-slack/src/message.coffee

Line 12 in 04079d0

# item_user - A String indicating the user that posted the item.

[y-i]

@aoberoi thank you,robot.react() seems to be fixed in #465.

but #465 looks like broken.

• robot.react() doesn't respond to the reaction message.
• robot.hear() throws exception when the incoming webhook message is posted.

[shaydewael]

@y-i Sorry about that (and thanks for pointing it out). That should be fixed with #475.