add support for cloze_drag_and_drop

lib/grader.rb

@@ -1,6 +1,6 @@
 Question = Struct.new(:question_type, :prompt)
 
-Choice = Struct.new(:key, :text, :correct)
+Choice = Struct.new(:key, :text, :correct, :correct_order)
 
 def grader(question, choices, responses)
     if question.question_type == "MULTIPLE_CHOICE"
@@ -10,7 +10,7 @@ def grader(question, choices, responses)
         correct_responses = choices[0].select { |choice| choice.correct }
         chosen_responses = choices[0].select { |choice| choice.correct && responses.include?(choice.key) }
         chosen_responses.size.to_f / correct_responses.size.to_f
-    elsif question.question_type = "MULTIPLE_DROPDOWNS"
+    elsif question.question_type == "MULTIPLE_DROPDOWNS"
         correct_responses = choices.to_enum(:each_with_index).collect do |dropdown_choice, index|
             current_response = responses[index]
             current_chosen_choice = dropdown_choice.detect { |choice| current_response == choice.key }
@@ -19,6 +19,20 @@ def grader(question, choices, responses)
             sum + curr_response
         end
         correct_responses / choices.size.to_f
+    elsif question.question_type == "CLOZE_DRAG_AND_DROP"
+        ccio = choices[0].sort_by { |choice| choice.correct_order }
+        ccio_keys = ccio.collect { |choice| choice.key }
+        if ccio_keys == responses
+            1.0
+        else
+            all_keys_present = true
+            for r in responses
+                if !ccio_keys.include?(r)
+                    all_keys_present = false
+                end
+            end
+            (all_keys_present) ? 0.5 : 0.0
+        end
     else
         0.0
     end

spec/grader_spec.rb

@@ -63,4 +63,20 @@
             expect(grader(question, choices, ["A", "C"])).to eq(0.5)
         end
     end
+
+    context "CLOZE_DRAG_AND_DROP" do
+        question = Question.new("CLOZE_DRAG_AND_DROP", "For {target1}, then {target2}.")
+        choices = [[
+            Choice.new("A", "A", true, 1),
+            Choice.new("B", "B", true, 2)
+        ]]
+
+        it("should return 1.0 if responses match correct choices in order") do
+            expect(grader(question, choices, ["A", "B"])).to eq(1.0)
+        end
+
+        it("should return 0.5 if responses are out of order") do
+            expect(grader(question, choices, ["B", "A"])).to eq(0.5)
+        end
+    end
 end