Fix duplicate records in investments by tag

When an investment had been assigned a user tag and a valuation tag with
the same name, it appeared twice when filtering by tag.

This is because by design, in order to provide compatibility with scopes
using "select" or "distinct", the method `tagged_with` doesn't select
unique records.

Forcing the query to return unique records solves the issue.

app/helpers/budget_executions_helper.rb

@@ -5,7 +5,7 @@ module BudgetExecutionsHelper
 
   def options_for_milestone_tags
     @budget.investments_milestone_tags.map do |tag|
-      ["#{tag} (#{@budget.investments.winners.tagged_with(tag).count})", tag]
+      ["#{tag} (#{@budget.investments.winners.by_tag(tag).count})", tag]
     end
   end
 

app/models/budget/investment.rb

@@ -98,7 +98,7 @@ class Budget
     scope :by_group,          ->(group_id)    { where(group_id: group_id) }
     scope :by_heading,        ->(heading_id)  { where(heading_id: heading_id) }
     scope :by_admin,          ->(admin_id)    { where(administrator_id: admin_id) }
-    scope :by_tag,            ->(tag_name)    { tagged_with(tag_name) }
+    scope :by_tag,            ->(tag_name)    { tagged_with(tag_name).distinct }
 
     scope :for_render, -> { includes(:heading) }
 

spec/helpers/budget_executions_helper_spec.rb

@@ -0,0 +1,17 @@
+require "rails_helper"
+
+describe BudgetExecutionsHelper do
+  describe "#options_for_milestone_tags" do
+    let(:budget) { create(:budget) }
+
+    it "does not return duplicate records for tags in different contexts" do
+      create(:budget_investment, :winner, budget: budget, milestone_tag_list: ["Multiple"])
+      create(:budget_investment, :winner, budget: budget, milestone_tag_list: ["Multiple"])
+      create(:budget_investment, :winner, budget: budget, milestone_tag_list: ["Dup"], tag_list: ["Dup"])
+
+      @budget = budget
+
+      expect(options_for_milestone_tags).to eq [["Dup (1)", "Dup"], ["Multiple (2)", "Multiple"]]
+    end
+  end
+end

spec/models/budget/investment_spec.rb

@@ -796,6 +796,14 @@ describe Budget::Investment do
 
         expect(investment.valuation_tag_list).to match_array(%w[Code Test Refactor])
       end
+
+      describe ".by_tag" do
+        it "does not return duplicate records for tags in different contexts" do
+          investment = create(:budget_investment, tag_list: ["Same"], valuation_tag_list: ["Same"])
+
+          expect(Budget::Investment.by_tag("Same")).to eq [investment]
+        end
+      end
     end
   end