Allow authenticated user to vote/remove vote on card, add idMembersVoted to card

lib/trello/card.rb

@@ -344,6 +344,38 @@ def remove_member(member)
       client.delete("/cards/#{id}/members/#{member.id}")
     end
 
+    # Current authenticated user upvotes a card
+    def upvote
+      begin
+        client.post("/cards/#{id}/membersVoted", {
+          value: get_authenticated_user_id
+        })
+      rescue Trello::Error => e
+        fail e unless e.message =~ /has already voted/i
+      end
+
+      self
+    end
+
+    # Recind upvote. Noop if authenticated user hasn't previously voted
+    def remove_upvote
+      begin
+        client.delete("/cards/#{id}/membersVoted/#{get_authenticated_user_id}")
+      rescue Trello::Error => e
+        fail e unless e.message =~ /has not voted/i
+      end
+
+      self
+    end
+
+    # FIXME: this doesn't belong here
+    # Is there a possibility of an application (not a user) that can be
+    # authenticated?
+    private def get_authenticated_user_id
+      mem = Member.from_response client.get('/members/me')
+      mem && mem.id
+    end
+
     # Add a label
     def add_label(label)
       unless label.valid?

spec/card_spec.rb

@@ -94,7 +94,7 @@ module Trello
 
         expect(card).to be_a Card
       end
-      
+
       it 'creates a duplicate card with source due date and checklists and saves it on Trello', refactor: true do
         payload = {
           source_card_id: cards_details.first['id'],
@@ -402,6 +402,53 @@ module Trello
       end
     end
 
+    context "votes" do
+      let(:authenticated_member) { double(id: '4ee7df3ce582acdec80000b2') }
+
+      before do
+        allow(card)
+          .to receive(:get_authenticated_user_id)
+          .and_return(authenticated_member.id)
+      end
+
+      it 'upvotes a card with the currently authenticated member' do
+        expect(client)
+          .to receive(:post)
+          .with("/cards/abcdef123456789123456789/membersVoted", {
+            value: authenticated_member.id
+          })
+
+        card.upvote
+      end
+
+      it 'returns the card even if the user has already upvoted' do
+        expect(client)
+          .to receive(:post)
+          .with("/cards/abcdef123456789123456789/membersVoted", {
+            value: authenticated_member.id
+          })
+          .and_raise(Trello::Error, 'member has already voted')
+        expect(card.upvote).to be_kind_of Trello::Card
+      end
+
+      it 'removes an upvote from a card' do
+        expect(client)
+          .to receive(:delete)
+          .with("/cards/abcdef123456789123456789/membersVoted/#{authenticated_member.id}")
+
+        card.remove_upvote
+      end
+
+      it 'returns card after remove_upvote even if the user has not previously upvoted it' do
+        expect(client)
+          .to receive(:delete)
+          .with("/cards/abcdef123456789123456789/membersVoted/#{authenticated_member.id}")
+          .and_raise(Trello::Error, 'member has not voted on the card')
+
+        card.remove_upvote
+      end
+    end
+
     context "comments" do
       it "posts a comment" do
         expect(client)