Refactor Variant Detail presentation (#47)

* split presenter goes away and VariantDetail handles view related details

app/controllers/admin/splits_controller.rb

@@ -4,6 +4,6 @@ def index
   end
 
   def show
-    @split = SplitPresenter.new(Split.find(params[:id]))
+    @split = Split.find(params[:id])
   end
 end

app/models/variant_detail.rb

@@ -8,6 +8,18 @@ def display_name
     super || variant
   end
 
+  def weight
+    @weight ||= split.variant_weight(variant)
+  end
+
+  def assignment_count
+    @assignment_count ||= split.assignment_count_for_variant(variant)
+  end
+
+  def retirable?
+    weight == 0 && assignment_count > 0
+  end
+
   private
 
   def variant_must_exist

app/views/admin/splits/_variants.html.erb

@@ -13,7 +13,7 @@
         <th></th>
       </thead>
       <tbody>
-        <% split.variant_details.each do |variant_detail| %>
+        <% split.detail.variant_details.each do |variant_detail| %>
           <tr>
             <td><%= variant_detail.display_name %></td>
             <td><%= variant_detail.description %></td>

spec/models/variant_detail_spec.rb

@@ -1,7 +1,68 @@
 require 'rails_helper'
 
 RSpec.describe VariantDetail do
-  let(:split) { FactoryGirl.create(:split, name: 'split_enabled', registry: { true: 50, false: 50 }) }
+  let(:split) { FactoryGirl.create(:split, name: "some_feature_enabled", registry: { true: 40, false: 60 }) }
+
+  describe "#weight" do
+    subject { described_class.new(split: split, variant: 'true') }
+
+    it "is the weight of the given variant" do
+      expect(subject.weight).to eq 40
+    end
+  end
+
+  describe "#assignment_count" do
+    let!(:true_assignment) { FactoryGirl.create(:assignment, split: split, variant: "true") }
+    let!(:false_assignment) { FactoryGirl.create_pair(:assignment, split: split, variant: "false") }
+
+    let(:true_presenter) { described_class.new(split: split, variant: 'true') }
+    let(:false_presenter) { described_class.new(split: split, variant: 'false') }
+
+    it "is the number of assignments of given variant" do
+      expect(true_presenter.assignment_count).to eq 1
+      expect(false_presenter.assignment_count).to eq 2
+    end
+  end
+
+  describe "#retirable?" do
+    subject { described_class.new(split: split, variant: 'true') }
+
+    context 'with a 0% weight' do
+      let(:split) { FactoryGirl.create(:split, name: "some_feature_enabled", registry: { true: 0, false: 100 }) }
+
+      context 'with no assignments' do
+        it "is false" do
+          expect(subject).not_to be_retirable
+        end
+      end
+
+      context 'with some assignments' do
+        let!(:assignment) { FactoryGirl.create(:assignment, split: split, variant: "true") }
+
+        it "is true" do
+          expect(subject).to be_retirable
+        end
+      end
+    end
+
+    context 'with a non0% weight' do
+      let(:split) { FactoryGirl.create(:split, name: "some_feature_enabled", registry: { true: 1, false: 99 }) }
+
+      context 'with no assignments' do
+        it "is false" do
+          expect(subject).not_to be_retirable
+        end
+      end
+
+      context 'with some assignments' do
+        let!(:assignment) { FactoryGirl.create(:assignment, split: split, variant: "true") }
+
+        it "is false for a non 0% weight that has assignments" do
+          expect(subject).not_to be_retirable
+        end
+      end
+    end
+  end
 
   describe '#valid?' do
     context 'with a variant that exists' do