Move group labels AR code into finder

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

app/controllers/groups/labels_controller.rb

@@ -10,10 +10,7 @@ class Groups::LabelsController < Groups::ApplicationController
   def index
     respond_to do |format|
       format.html do
-        @labels = @group.labels
-          .optionally_search(params[:search])
-          .order_by(sort)
-          .page(params[:page])
+        @labels = GroupLabelsFinder.new(@group, params.merge(sort: sort)).execute
       end
       format.json do
         render json: LabelSerializer.new.represent_appearance(available_labels)

app/finders/group_labels_finder.rb

@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+class GroupLabelsFinder
+  attr_reader :group, :params
+
+  def initialize(group, params = {})
+    @group = group
+    @params = params
+  end
+
+  def execute
+    group.labels
+      .optionally_search(params[:search])
+      .order_by(params[:sort])
+      .page(params[:page])
+  end
+end

spec/finders/group_labels_finder_spec.rb

@@ -0,0 +1,33 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe GroupLabelsFinder, '#execute' do
+  let!(:group) { create(:group) }
+  let!(:label1) { create(:group_label, title: 'Foo', description: 'Lorem ipsum', group: group) }
+  let!(:label2) { create(:group_label, title: 'Bar', description: 'Fusce consequat', group: group) }
+
+  it 'returns all group labels sorted by name if no params' do
+    result = described_class.new(group).execute
+
+    expect(result.to_a).to match_array([label2, label1])
+  end
+
+  it 'returns all group labels sorted by name desc' do
+    result = described_class.new(group, sort: 'name_desc').execute
+
+    expect(result.to_a).to match_array([label2, label1])
+  end
+
+  it 'returns group labels that march search' do
+    result = described_class.new(group, search: 'Foo').execute
+
+    expect(result.to_a).to match_array([label1])
+  end
+
+  it 'returns second page of labels' do
+    result = described_class.new(group, page: '2').execute
+
+    expect(result.to_a).to match_array([])
+  end
+end