Merge branch 'precalculate-trending-projects' into 'master'

Precalculate trending projects

## What does this MR do?

This MR changes the trending projects code so that data is precalculated, removing the need for any complex caching mechanisms. 

## Why was this MR needed?

Caching of trending data didn't work properly, still leading to queries. Using caching in general would be very hard due to users being able to apply custom filters to the list of trending projects.

See merge request !6749

2 files changed, 60 insertions, 22 deletions

diff --git a/spec/models/project_spec.rb b/spec/models/project_spec.rb
index 8aadfcb439b..dae546a0cdc 100644
--- a/spec/models/project_spec.rb
+++ b/spec/models/project_spec.rb
@@ -800,32 +800,14 @@ describe Project, models: true do
       end
 
       create(:note_on_commit, project: project2)
-    end
-
-    describe 'without an explicit start date' do
-      subject { described_class.trending.to_a }
 
-      it 'sorts Projects by the amount of notes in descending order' do
-        expect(subject).to eq([project1, project2])
-      end
+      TrendingProject.refresh!
     end
 
-    describe 'with an explicit start date' do
-      let(:date) { 2.months.ago }
+    subject { described_class.trending.to_a }
 
-      subject { described_class.trending(date).to_a }
-
-      before do
-        2.times do
-          # Little fix for special issue related to Fractional Seconds support for MySQL.
-          # See: https://github.com/rails/rails/pull/14359/files
-          create(:note_on_commit, project: project2, created_at: date + 1)
-        end
-      end
-
-      it 'sorts Projects by the amount of notes in descending order' do
-        expect(subject).to eq([project2, project1])
-      end
+    it 'sorts projects by the amount of notes in descending order' do
+      expect(subject).to eq([project1, project2])
     end
 
     it 'does not take system notes into account' do
diff --git a/spec/models/trending_project_spec.rb b/spec/models/trending_project_spec.rb
new file mode 100644
index 00000000000..cc28c6d4004
--- /dev/null
+++ b/spec/models/trending_project_spec.rb
@@ -0,0 +1,56 @@
+require 'spec_helper'
+
+describe TrendingProject do
+  let(:user) { create(:user) }
+  let(:public_project1) { create(:empty_project, :public) }
+  let(:public_project2) { create(:empty_project, :public) }
+  let(:public_project3) { create(:empty_project, :public) }
+  let(:private_project) { create(:empty_project, :private) }
+  let(:internal_project) { create(:empty_project, :internal) }
+
+  before do
+    3.times do
+      create(:note_on_commit, project: public_project1)
+    end
+
+    2.times do
+      create(:note_on_commit, project: public_project2)
+    end
+
+    create(:note_on_commit, project: public_project3, created_at: 5.weeks.ago)
+    create(:note_on_commit, project: private_project)
+    create(:note_on_commit, project: internal_project)
+  end
+
+  describe '.refresh!' do
+    before do
+      described_class.refresh!
+    end
+
+    it 'populates the trending projects table' do
+      expect(described_class.count).to eq(2)
+    end
+
+    it 'removes existing rows before populating the table' do
+      described_class.refresh!
+
+      expect(described_class.count).to eq(2)
+    end
+
+    it 'stores the project IDs for every trending project' do
+      rows = described_class.order(id: :asc).all
+
+      expect(rows[0].project_id).to eq(public_project1.id)
+      expect(rows[1].project_id).to eq(public_project2.id)
+    end
+
+    it 'does not store projects that fall out of the trending time range' do
+      expect(described_class.where(project_id: public_project3).any?).to eq(false)
+    end
+
+    it 'stores only public projects' do
+      expect(described_class.where(project_id: [public_project1.id, public_project2.id]).count).to eq(2)
+      expect(described_class.where(project_id: [private_project.id, internal_project.id]).count).to eq(0)
+    end
+  end
+end