Feature: assign author and comment on PR if a merge conflict occurs after a correct pr is merged

[ghost]

When a PR has "awaiting-review" & merge conflict then remove awaiting review label, add "resolving-merge-conflict" label, assign the author of the PR and add comment on the issue with "@username before proceeding with review, please resolve the merge conflict and then reassign."

[SimonLab]

Hopefully Github will trigger an event when a merge conflict occurs. If it's the case this should be quiet straightforward to implement as it follow the same login as in #58

[SimonLab]

Unfortunately Github doesn't seem to trigger any events when a PR has a merge conflict.
However we could catch the event when a PR is merged, get the list of all the open PR and check if the PRs with "awaiting-review" has any merge conflicts

The rule merge-conflict is triggered by the event: pull request closed
do get the list of open PRs
If PRs have "awaiting-review" label AND PRs can't be merged
Then

• add a comment on the PR: "@{author_PR}, the pull request has some merge conflict, please resolved them and reassign when ready, thanks 👍"
• remove "awaiting-review" label
• add "merge-conflict" label

[SimonLab]

changing time estimate to 4h. I've already spend 1h looking for a github event when a merge conflict occurs (doesn't exist). Compare to the other rules implemented so far, this rule require a bit more logic on the backend (fetching all the open PRs, checking for errors on all these PRs, reporting for erorr for all the PRs).
Also on this specific rule we shouldn't have dwylbot to wait before commenting on the PR. The error report should be direct. So I will need first to implement #74 (define waiting time per rule) first

[SimonLab]

Unfortunately a github app doesn't seem to have the right to remove reviewers when a PR has some merge conlflicts:

%HTTPoison.Response{body: "{\"message\":\"Validation Failed\",\"errors\":[\"Must have push access to this repository to add review requests.\"],\"documentation_url\":\"https://developer.github.com/v3/schema/pull-request-review-request\"}"

However I don't think this is a big blocker as we already remove the assignees.

[ghost]

@SimonLab these parts don't happen:

remove "awaiting-review" label
add "merge-conflict" label

#118

also note your own app is posting too

[SimonLab]

myapp has been removed, I'll have a look if I can reproduce the error

[SimonLab]

The merge conflict can only be checked when a PR is merged:

• a correct PR is merged
• dwylbot get all the other open PRs and check for merge conflict
• for each of the PRs with merge conflict add an error commnent.

Agree that it would be great to have a more dynamic check. I think this will be a similar rule but the trigger is different. We need a rule that is trigger when a PR is created/opened also, I'll create an issue for that, thanks for testing the rule 👍
You can leave your test PR open and as soon as another PR is merged dwylbot should report the merge conflict. If this happen I think this issue can be close and I will work on the other one.

[ghost]

Waiting on #118 (comment)

[ghost]

@SimonLab dwylbot has not reported a merge conflict here: dwyl/dwylbot-test#1

[naazy]

@markwilliamfirth I believe dwylbot did not report a merge conflict due to @SimonLab's comment #64 (comment) . We only check for a merge conflicts when a (different) PR is merged.

[ghost]

Replaced by #64