Code improvements on burndown model and view partial

app/models/burndown.rb

@@ -7,15 +7,12 @@ class Burndown
     @end_date = @milestone.due_date
     @end_date = Date.today if @end_date.present? && @end_date > Date.today
 
-    milestone_issues = @milestone.issues
-
-    @issues_count  = milestone_issues.count
-    @issues_weight = milestone_issues.sum(:weight)
+    @issues_count, @issues_weight = milestone.issues.reorder(nil).pluck('COUNT(*), COALESCE(SUM(weight), 0)').first
   end
 
   # Returns the chart data in the following format:
   # [date, issue count, issue weight] eg: [["2017-03-01", 33, 127], ["2017-03-02", 35, 73], ["2017-03-03", 28, 50]...]
-  def chart_data
+  def as_json(opts = nil)
     return [] unless valid?
 
     open_issues_count  = issues_count
@@ -27,7 +24,10 @@ class Burndown
       closed_issues_count = closed.count
       closed_issues_weight = sum_issues_weight(closed)
 
-      chart_data << [date.strftime("%Y-%m-%d"), open_issues_count -= closed_issues_count, open_issues_weight -= closed_issues_weight]
+      open_issues_count -= closed_issues_count
+      open_issues_weight -= closed_issues_weight
+
+      chart_data << [date.strftime("%Y-%m-%d"), open_issues_count, open_issues_weight]
 
       reopened_count = reopened.count
       reopened_weight = sum_issues_weight(reopened)
@@ -44,20 +44,20 @@ class Burndown
   private
 
   def sum_issues_weight(issues)
-    issues.map(&:weight).compact.reduce(:+) || 0
+    issues.map(&:weight).sum
   end
 
   def closed_and_reopened_issues_by(date)
-    current_date = date.beginning_of_day
+    current_date = date.to_date
 
-    closed   = issues_with_closed_at.select { |issue| issue.closed_at.beginning_of_day.to_i == current_date.to_i }
+    closed   = issues_with_closed_at.select { |issue| issue.closed_at.to_date == current_date }
     reopened = closed.select { |issue| issue.state == 'reopened' }
 
     return closed, reopened
   end
 
   def issues_with_closed_at
-    @issues ||=
+    @issues_with_closed_at ||=
       @milestone.issues.select('closed_at, weight, state').
         where('closed_at IS NOT NULL').
         order('closed_at ASC')

app/views/shared/milestones/_burndown.html.haml

@@ -16,7 +16,7 @@
           Issues
         %button.btn.btn-xs{ data: { show: 'weight' } }
           Issue weight
-  .burndown-chart{ data: { start_date: milestone.start_date.strftime("%Y-%m-%d"), due_date: milestone.due_date.strftime("%Y-%m-%d"), chart_data: burndown.chart_data.to_json } }
+  .burndown-chart{ data: { start_date: burndown.start_date.strftime("%Y-%m-%d"), due_date: burndown.end_date.strftime("%Y-%m-%d"), chart_data: burndown.to_json } }
 
 - elsif can?(current_user, :admin_milestone, @project) && cookies['hide_burndown_message'].nil?
   .burndown-hint.content-block.container-fluid

spec/models/burndown_spec.rb

@@ -27,7 +27,7 @@ describe Burndown, models: true do
     Timecop.return
   end
 
-  subject { described_class.new(milestone).chart_data }
+  subject { described_class.new(milestone).to_json }
 
   it "generates an array with date, issue count and weight" do
     expect(subject).to eq([
@@ -36,25 +36,25 @@ describe Burndown, models: true do
       ["2017-03-03", 28, 56],
       ["2017-03-04", 32, 64],
       ["2017-03-05", 21, 42]
-    ])
+    ].to_json)
   end
 
   it "returns empty array if milestone start date is nil" do
     milestone.update(start_date: nil)
 
-    expect(subject).to eq([])
+    expect(subject).to eq([].to_json)
   end
 
   it "returns empty array if milestone due date is nil" do
     milestone.update(due_date: nil)
 
-    expect(subject).to eq([])
+    expect(subject).to eq([].to_json)
   end
 
   it "it counts until today if milestone due date > Date.today" do
     Timecop.travel(milestone.due_date - 1.day)
 
-    expect(subject.last[0]).to eq(Time.now.strftime("%Y-%m-%d"))
+    expect(JSON.parse(subject).last[0]).to eq(Time.now.strftime("%Y-%m-%d"))
   end
 
   # Creates, closes and reopens issues only for odd days numbers