Fix slack username validation on intake form

app/controllers/v1/leaders_controller.rb

@@ -6,7 +6,8 @@ class LeadersController < ApplicationController
 
     def intake
       leader = Leader.new(
-        leader_params.merge(club_ids: [club_id], slack_team_id: TEAM_ID)
+        leader_params.merge(club_ids: [club_id], slack_username: slack_username,
+                            slack_team_id: TEAM_ID)
       )
 
       if leader.save
@@ -24,6 +25,10 @@ def club_id
       params[:club_id]
     end
 
+    def slack_username
+      params[:slack_username].strip
+    end
+
     def verify_club_id
       return unless club_id.nil?
       render json: { errors: { club_id: ["can't be blank"] } }, status: 422

app/models/leader.rb

@@ -60,6 +60,7 @@ class Leader < ApplicationRecord
   end
 
   validates :name, presence: true
+  validate :validate_slack_username_found
 
   def slack_update
     return if access_token.nil?
@@ -80,6 +81,11 @@ def timezone
 
   private
 
+  def validate_slack_username_found
+    return unless user_from_username(slack_username).nil?
+    errors.add(:slack_username, 'Slack user not found')
+  end
+
   def slack_id_sync
     info = SlackClient::Users.info(slack_id, access_token)[:user]
     self.slack_username = info[:name] unless info.nil?