FIX: check the selected options when casting a vote

plugins/poll/config/locales/server.en.yml

@@ -19,6 +19,7 @@ en:
     default_poll_must_have_different_options: "Poll must have different options."
     named_poll_must_have_different_options: "Poll name <strong>%{name}</strong> must have different options."
 
+    requires_at_least_1_valid_option: "You must select at least 1 valid option."
     cannot_change_polls_after_5_minutes: "Polls cannot be changed after the first 5 minutes. Contact a moderator if you need to change them."
     staff_cannot_add_or_remove_options_after_5_minutes: "After the first 5 minutes, poll options can only be edited, not added or removed. If you need to add or remove options, you should close this topic and create a new one."
 

plugins/poll/plugin.rb

@@ -47,9 +47,16 @@ after_initialize do
           raise StandardError.new I18n.t("poll.no_poll_with_this_name", name: poll_name) if poll.blank?
           raise StandardError.new I18n.t("poll.poll_must_be_open_to_vote") if poll["status"] != "open"
 
+          # remove options that aren't available in the poll
+          available_options = poll["options"].map { |o| o["id"] }.to_set
+          options.select! { |o| available_options.include?(o) }
+
+          raise StandardError.new I18n.t("poll.requires_at_least_1_valid_option") if options.empty?
+
           votes = post.custom_fields["#{VOTES_CUSTOM_FIELD}-#{user_id}"] || {}
           vote = votes[poll_name] || []
 
+          # increment counters only when the user hasn't casted a vote yet
           poll["total_votes"] += 1 if vote.size == 0
 
           poll["options"].each do |option|

plugins/poll/spec/controllers/polls_controller_spec.rb

@@ -12,13 +12,21 @@ describe ::DiscoursePoll::PollsController do
     it "works" do
       DiscourseBus.expects(:publish)
 
-      xhr :put, :vote, { post_id: poll.id, poll_name: "poll", options: ["A"] }
+      xhr :put, :vote, { post_id: poll.id, poll_name: "poll", options: ["5c24fc1df56d764b550ceae1b9319125"] }
 
       expect(response).to be_success
       json = ::JSON.parse(response.body)
       expect(json["poll"]["name"]).to eq("poll")
       expect(json["poll"]["total_votes"]).to eq(1)
-      expect(json["vote"]).to eq(["A"])
+      expect(json["vote"]).to eq(["5c24fc1df56d764b550ceae1b9319125"])
+    end
+
+    it "requires at least 1 valid option" do
+      xhr :put, :vote, { post_id: poll.id, poll_name: "poll", options: ["A", "B"] }
+
+      expect(response).not_to be_success
+      json = ::JSON.parse(response.body)
+      expect(json["errors"][0]).to eq(I18n.t("poll.requires_at_least_1_valid_option"))
     end
 
     it "supports vote changes" do