address code review remarks, cleanup testacases

app/controllers/projects/prometheus/metrics_controller.rb

@@ -2,11 +2,8 @@ module Projects
   module Prometheus
     class MetricsController < Projects::ApplicationController
       before_action :authorize_admin_project!
-      before_action :require_prometheus_metrics!
 
       def active_common
-        render_404 unless prometheus_service.present?
-
         respond_to do |format|
           format.json do
             matched_metrics = prometheus_service.matched_metrics || {}
@@ -21,8 +18,6 @@ module Projects
       end
 
       def validate_query
-        render_404 unless prometheus_service.present?
-
         respond_to do |format|
           format.json do
             result = prometheus_service.validate_query(params[:query])
@@ -87,7 +82,7 @@ module Projects
 
         respond_to do |format|
           format.html do
-            redirect_to edit_project_service_path(project, prometheus_service), status: 303
+            redirect_to edit_project_service_path(project, PrometheusService), status: 303
           end
           format.json do
             head :ok
@@ -104,10 +99,6 @@ module Projects
       def prometheus_service
         @prometheus_service ||= project.find_or_initialize_service('prometheus')
       end
-
-      def require_prometheus_metrics!
-        render_404 unless prometheus_service.present?
-      end
     end
   end
 end

app/models/prometheus_metric.rb

@@ -6,14 +6,14 @@ class PrometheusMetric < ActiveRecord::Base
   validates :query, presence: true
   validates :group, presence: true
 
-  GROUP_NAMES = {
+  GROUP_TITLES = {
     business: 'Business metrics',
     response: 'Response metrics',
     system: 'System metrics'
   }.freeze
 
-  def group_text
-    GROUP_NAMES[group.to_sym]
+  def group_title
+    GROUP_TITLES[group.to_sym]
   end
 
   def to_query_metric

app/serializers/prometheus_metric_entity.rb

@@ -4,6 +4,9 @@ class PrometheusMetricEntity < Grape::Entity
   expose :id
   expose :title
 
+  expose :group
+  expose :group_title
+
   expose :edit_path do |prometheus_metric|
     edit_project_prometheus_metric_path(prometheus_metric.project, prometheus_metric)
   end

lib/gitlab/prometheus/metric_group.rb

@@ -15,7 +15,7 @@ module Gitlab
       end
 
       def self.custom_metrics(project)
-        project.prometheus_metrics.all.group_by(&:group_text).map do |name, metrics|
+        project.prometheus_metrics.all.group_by(&:group_title).map do |name, metrics|
           MetricGroup.new(name: name, priority: 0, metrics: metrics.map(&:to_query_metric))
         end
       end

spec/ee/fixtures/api/schemas/prometheus/metrics.json

@@ -12,6 +12,12 @@
           "title": {
             "type": "string"
           },
+          "group": {
+            "type": "string"
+          },
+          "group_title": {
+            "type": "string"
+          },
           "edit_path": {
             "type": "string"
           }

spec/ee/spec/controllers/projects/prometheus/metrics_controller_spec.rb

@@ -45,7 +45,6 @@ describe Projects::Prometheus::MetricsController do
   describe 'GET #index' do
     context 'with custom metric present' do
       let!(:prometheus_metric) { create(:prometheus_metric, project: project) }
-      let(:metrics_list_repsonse) {  }
 
       it 'returns a list of metrics' do
         get :index, project_params(format: :json)

spec/lib/gitlab/import_export/all_models.yml

@@ -324,4 +324,3 @@ issue_assignees:
 epic_issues:
 - issue
 - epic
-

spec/lib/gitlab/prometheus/queries/validate_query_spec.rb

@@ -25,6 +25,8 @@ describe Gitlab::Prometheus::Queries::ValidateQuery do
 
     it 'passes query to prometheus' do
       expect(subject.query(query)).to eq(valid: false, error: message)
+
+      expect(client).to have_received(:query).with(query)
     end
   end
 end

spec/models/prometheus_metric_spec.rb

@@ -11,17 +11,17 @@ describe PrometheusMetric, type: :model do
   describe '#group_text' do
     let!(:metric) { create(:prometheus_metric) }
 
-    shared_examples 'group_text' do |group, text|
-      subject { build(:prometheus_metric, group: group) }
+    shared_examples 'group_title' do |group, text|
+      subject { build(:prometheus_metric, group: group).group_title }
 
       it "returns text #{text} for group #{group}" do
-        expect(subject.group_text).to eq(text)
+        expect(subject).to eq(text)
       end
     end
 
-    it_behaves_like 'group_text', :business, 'Business metrics'
-    it_behaves_like 'group_text', :response, 'Response metrics'
-    it_behaves_like 'group_text', :system, 'System metrics'
+    it_behaves_like 'group_title', :business, 'Business metrics'
+    it_behaves_like 'group_title', :response, 'Response metrics'
+    it_behaves_like 'group_title', :system, 'System metrics'
   end
 
   describe '#to_query_metric' do
@@ -45,10 +45,6 @@ describe PrometheusMetric, type: :model do
       expect(subject.to_query_metric.weight).to eq(0)
     end
 
-    it 'queryable metric has weight 0' do
-      expect(subject.to_query_metric.weight).to eq(0)
-    end
-
     it 'queryable metrics has query description' do
       queries = [
         {