Add issue search slash command

One of many requested in: gitlab-org/gitlab-ce#24768

changelogs/unreleased/zj-issue-search-slash-command.yml

+---
+title: Add issue search slash command
+merge_request: 
+author: 

lib/gitlab/chat_commands/base_command.rb

@@ -40,9 +40,7 @@ module Gitlab
       private
 
       def find_by_iid(iid)
-        resource = collection.find_by(iid: iid)
-
-        readable?(resource) ? resource : nil
+        collection.find_by(iid: iid)
       end
     end
   end

lib/gitlab/chat_commands/command.rb

@@ -4,6 +4,7 @@ module Gitlab
       COMMANDS = [
         Gitlab::ChatCommands::IssueShow,
         Gitlab::ChatCommands::IssueCreate,
+        Gitlab::ChatCommands::IssueSearch,
         Gitlab::ChatCommands::Deploy,
       ].freeze
 

lib/gitlab/chat_commands/issue_command.rb

@@ -6,11 +6,7 @@ module Gitlab
       end
 
       def collection
-        project.issues
-      end
-
-      def readable?(issue)
-        self.class.can?(current_user, :read_issue, issue)
+        IssuesFinder.new(current_user, project_id: project.id).execute
       end
     end
   end

lib/gitlab/chat_commands/issue_search.rb

+module Gitlab
+  module ChatCommands
+    class IssueSearch < IssueCommand
+      def self.match(text)
+        /\Aissue\s+search\s+(?<query>.*)/.match(text)
+      end
+
+      def self.help_message
+        "issue search <your query>"
+      end
+
+      def execute(match)
+        collection.search(match[:query]).limit(QUERY_LIMIT)
+      end
+    end
+  end
+end

spec/lib/gitlab/chat_commands/issue_search_spec.rb

+require 'spec_helper'
+
+describe Gitlab::ChatCommands::IssueSearch, service: true do
+  describe '#execute' do
+    let!(:issue) { create(:issue, title: 'find me') }
+    let!(:confidential) { create(:issue, :confidential, project: project, title: 'mepmep find') }
+    let(:project) { issue.project }
+    let(:user) { issue.author }
+    let(:regex_match) { described_class.match("issue search find") }
+
+    subject do
+      described_class.new(project, user).execute(regex_match)
+    end
+
+    context 'when the user has no access' do
+      it 'only returns the open issues' do
+        expect(subject).not_to include(confidential)
+      end
+    end
+
+    context 'the user has access' do
+      before do
+        project.team << [user, :master]
+      end
+
+      it 'returns all results' do
+        expect(subject).to include(confidential, issue)
+      end
+    end
+
+    context 'without hits on the query' do
+      it 'returns an empty collection' do
+        expect(subject).to be_empty
+      end
+    end
+  end
+
+  describe 'self.match' do
+    let(:query) { "my search keywords" }
+    it 'matches the query' do
+      match = described_class.match("issue search #{query}")
+
+      expect(match[:query]).to eq(query)
+    end
+  end
+end

spec/requests/api/services_spec.rb

@@ -128,7 +128,7 @@ describe API::API, api: true  do
           )
         end
 
-        it 'retusn status 200' do
+        it 'returns status 200' do
           post api("/projects/#{project.id}/services/mattermost_slash_commands/trigger"), params
 
           expect(response).to have_http_status(200)