Fix edge case

The user was able to vote as many investments as wanted in the first
heading voted. However in the second heading voted, only one investment
could be voted

This was due to the previous implementation, where you could only vote
in one heading. Note the `first` call in method
`heading_voted_by_user?(user)`

This commits simplifies the logic and allows voting for any investment
in any heading that the user has previously voted in

app/models/budget/investment.rb

@@ -231,7 +231,7 @@ class Budget
     end
 
     def valid_heading?(user)
-      voted_in?([heading.id], user) ||
+      voted_in?(heading, user) ||
       can_vote_in_another_heading?(user)
     end
 
@@ -243,13 +243,8 @@ class Budget
       user.votes.for_budget_investments(budget.investments.where(group: group)).votables.map(&:heading_id).uniq
     end
 
-    def voted_in?(heading_ids, user)
+    def voted_in?(heading, user)
-      heading_ids.include? heading_voted_by_user?(user)
+      headings_voted_by_user(user).include?(heading.id)
-    end
-
-    def heading_voted_by_user?(user)
-      user.votes.for_budget_investments(budget.investments.where(group: group))
-          .votables.map(&:heading_id).first
     end
 
     def ballotable_by?(user)

spec/models/budget/investment_spec.rb

@@ -603,6 +603,22 @@ describe Budget::Investment do
         expect(salamanca_investment.valid_heading?(user)).to eq(true)
       end
 
+      it "accepts votes in any heading previously voted in" do
+        group.update(max_votable_headings: 2)
+
+        carabanchel = create(:budget_heading, group: group)
+        salamanca   = create(:budget_heading, group: group)
+
+        carabanchel_investment = create(:budget_investment, heading: carabanchel)
+        salamanca_investment   = create(:budget_investment, heading: salamanca)
+
+        create(:vote, votable: carabanchel_investment, voter: user)
+        create(:vote, votable: salamanca_investment, voter: user)
+
+        expect(carabanchel_investment.valid_heading?(user)).to eq(true)
+        expect(salamanca_investment.valid_heading?(user)).to eq(true)
+      end
+
       it "allows votes in a group with a single heading" do
         all_city_investment = create(:budget_investment, heading: heading)
         expect(all_city_investment.valid_heading?(user)).to eq(true)
@@ -702,6 +718,23 @@ describe Budget::Investment do
     end
   end
 
+  describe "#voted_in?" do
+
+    let(:user) { create(:user) }
+    let(:investment) { create(:budget_investment) }
+
+    it "returns true if the user has voted in this heading" do
+      create(:vote, votable: investment, voter: user)
+
+      expect(investment.voted_in?(investment.heading, user)).to eq(true)
+    end
+
+    it "returns false if the user has not voted in this heading" do
+      expect(investment.voted_in?(investment.heading, user)).to eq(false)
+    end
+
+  end
+
   describe "Order" do
     describe "#sort_by_confidence_score" do