Saving settings for Mattermost Notifications integration displays error

Summary

When configuring the Mattermost Notifications integration for a project, when you click the "Test settings and save changes" button, any changes you've made are saved, but a toast banner reading "Test failed. false Save anyway" is displayed at the top of the screen.

There don't appear to be any errors displayed in the logs, and the network request made when clicking the button returns a 200 status.

Steps to reproduce

  1. Create a new project in GitLab
  2. Create an incoming webhook in Mattermost to use for notifications
    1. In Mattermost, click on the main menu and select Integrations
    2. Click on Incoming Webhooks
    3. Click Add Incoming Webhook in the top right
    4. Select any channel in Mattermost
    5. Click Save
    6. Copy the URL of the newly created webhook for use later
  3. Go to Project Settings > Integrations
  4. Edit the "Mattermost notifications" integration
  5. Check the "Active" checkbox and enter the "Webhook" URL created earlier
  6. Click "Test settings and save changes"

Example Project

This is happening on a local installation of GitLab and Mattermost using GitLab Omnibus. I haven't tested it on GitLab.com

What is the current bug behavior?

The toast banner (shown below) is displayed and changes are saved.

What is the expected correct behavior?

Changes are saved and no toast banner is displayed.

Relevant logs and/or screenshots

Output of checks

Results of GitLab environment info

Expand for output related to GitLab environment info 
**************************************************
⛔️ WARNING: Sidekiq testing API enabled, but this is not the test environment.  Your jobs will not go to Redis.
**************************************************

System information
System:		Ubuntu 18.04
Current User:	git
Using RVM:	no
Ruby Version:	2.6.3p62
Gem Version:	2.7.9
Bundler Version:1.17.3
Rake Version:	12.3.3
Redis Version:	3.2.12
Git Version:	2.22.0
Sidekiq Version:5.2.7
Go Version:	unknown


GitLab information
Version:	12.6.0-pre
Revision:	6a7cc8c1472
Directory:	/opt/gitlab/embedded/service/gitlab-rails
DB Adapter:	PostgreSQL
DB Version:	10.9
URL:		http://harrison-gitlab.dev.spinmint.com
HTTP Clone URL:	http://harrison-gitlab.dev.spinmint.com/some-group/some-project.git
SSH Clone URL:	git@harrison-gitlab.dev.spinmint.com:some-group/some-project.git
Using LDAP:	no
Using Omniauth:	yes
Omniauth Providers:


GitLab Shell
Version:	10.3.0
Repository storage paths:
  • default: /var/opt/gitlab/git-data/repositories GitLab Shell path: /opt/gitlab/embedded/service/gitlab-shell Git: /opt/gitlab/embedded/bin/git

Results of GitLab application Check

Expand for output related to the GitLab application check 
**************************************************
⛔️ WARNING: Sidekiq testing API enabled, but this is not the test environment.  Your jobs will not go to Redis.
**************************************************
Checking GitLab subtasks ...

Checking GitLab Shell ...


GitLab Shell: ... GitLab Shell version >= 10.3.0 ? ... OK (10.3.0)
Running /opt/gitlab/embedded/service/gitlab-shell/bin/check
Internal API available: OK
Redis available via internal API: OK
gitlab-shell self-check successful


Checking GitLab Shell ... Finished


Checking Gitaly ...


Gitaly: ... default ... OK


Checking Gitaly ... Finished


Checking Sidekiq ...


Sidekiq: ... Running? ... yes
Number of Sidekiq processes ... 1


Checking Sidekiq ... Finished


Checking Incoming Email ...


Incoming Email: ... Reply by email is disabled in config/gitlab.yml


Checking Incoming Email ... Finished


Checking LDAP ...


LDAP: ... LDAP is disabled in config/gitlab.yml


Checking LDAP ... Finished


Checking GitLab App ...


Git configured correctly? ... yes
Database config exists? ... yes
All migrations up? ... yes
Database contains orphaned GroupMembers? ... no
GitLab config exists? ... yes
GitLab config up to date? ... yes
Log directory writable? ... yes
Tmp directory writable? ... yes
Uploads directory exists? ... yes
Uploads directory has correct permissions? ... yes
Uploads directory tmp has correct permissions? ... skipped (no tmp uploads folder yet)
Init script exists? ... skipped (omnibus-gitlab has no init script)
Init script up-to-date? ... skipped (omnibus-gitlab has no init script)
Projects have namespace: ...
2/1 ... yes
4/2 ... yes
Redis version >= 2.8.0? ... yes
Ruby version >= 2.5.3 ? ... yes (2.6.3)
Git version >= 2.22.0 ? ... yes (2.22.0)
Git user has default SSH configuration? ... yes
Active users: ... 1
Is authorized keys file accessible? ... yes


Checking GitLab App ... Finished


Checking GitLab subtasks ... Finished

Possible fixes

I haven't looked into it too much, but it seems like the code that controls the toast just has a minor issue since "false" sounds like there was no error.