Quiz Stats - Normalize input

Ensure all input hashes are using symbol keys.

Closes CNVS-13158

TEST PLAN
---- ----

Code changes. Test plan is similar to
https://gerrit.instructure.com/#/c/35096/

Change-Id: Ie1db45e2a5875e410a758c0b2f14594345212b5d
Reviewed-on: https://gerrit.instructure.com/35098
Reviewed-by: Derek DeVries <ddevries@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>
QA-Review: Caleb Guanzon <cguanzon@instructure.com>
Product-Review: Ahmad Amireh <ahmad@instructure.com>

app/models/quizzes/quiz_statistics/student_analysis.rb

@@ -360,6 +360,10 @@ class Quizzes::QuizStatistics::StudentAnalysis < Quizzes::QuizStatistics::Report
   #   "multiple_responses"=>false}],
   def stats_for_question(question, responses)
     if CQS.can_analyze?(question)
+      # the gem expects all hash keys to be symbols:
+      question = CQS::Util.deep_symbolize_keys(question)
+      responses = responses.map(&CQS::Util.method(:deep_symbolize_keys))
+
       analysis = CQS.analyze(question, responses)
 
       return question.to_hash.merge(analysis).with_indifferent_access

gems/canvas_quiz_statistics/lib/canvas_quiz_statistics.rb

@@ -1,5 +1,6 @@
 module CanvasQuizStatistics
   require 'canvas_quiz_statistics/version'
+  require 'canvas_quiz_statistics/util'
   require 'canvas_quiz_statistics/analyzers'
 
   def self.can_analyze?(question_data)

gems/canvas_quiz_statistics/lib/canvas_quiz_statistics/util.rb

@@ -0,0 +1,39 @@
+#
+# Copyright (C) 2014 Instructure, Inc.
+#
+# This file is part of Canvas.
+#
+# Canvas is free software: you can redistribute it and/or modify it under
+# the terms of the GNU Affero General Public License as published by the Free
+# Software Foundation, version 3 of the License.
+#
+# Canvas is distributed in the hope that it will be useful, but WITHOUT ANY
+# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+# A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
+# details.
+#
+# You should have received a copy of the GNU Affero General Public License along
+# with this program. If not, see <http://www.gnu.org/licenses/>.
+#
+module CanvasQuizStatistics
+  module Util
+    # Converts a hash to use symbol keys.
+    #
+    # Works on nested hashes, and hashes inside of arrays.
+    def self.deep_symbolize_keys(input)
+      return input unless input.is_a?(Hash)
+
+      input.inject({}) do |result, (key, value)|
+        new_key = key.is_a?(String) ? key.to_sym : key
+        new_value = case value
+                    when Hash then deep_symbolize_keys(value)
+                    when Array then value.map(&method(:deep_symbolize_keys))
+                    else value
+                    end
+
+        result[new_key] = new_value
+        result
+      end
+    end
+  end
+end

gems/canvas_quiz_statistics/spec/canvas_quiz_statistics/util_spec.rb

@@ -0,0 +1,93 @@
+require 'spec_helper'
+
+describe CanvasQuizStatistics::Util do
+  Util = CanvasQuizStatistics::Util
+
+  describe '#deep_symbolize_keys' do
+    it 'does nothing on anything but a Hash' do
+      Util.deep_symbolize_keys(5).should == 5
+      Util.deep_symbolize_keys([]).should == []
+      Util.deep_symbolize_keys(nil).should == nil
+    end
+
+    it 'should symbolize top-level keys' do
+      Util.deep_symbolize_keys({ 'a' => 'b', c: 'd' }).should == {
+        a: 'b',
+        c: 'd'
+      }
+    end
+
+    it 'should symbolize keys of nested hashes' do
+      Util.deep_symbolize_keys({
+        'e' => {
+          'f' => 'g',
+          h: 'i'
+        }
+      }).should == {
+        e: {
+          f: 'g',
+          h: 'i'
+        }
+      }
+    end
+
+    it 'should symbolize keys of hashes inside arrays' do
+      Util.deep_symbolize_keys({
+        'e' => [{
+          'f' => 'g',
+          h: 'i'
+        }]
+      }).should == {
+        e: [{
+          f: 'g',
+          h: 'i'
+        }]
+      }
+    end
+
+    it 'should symbolize all sorts of things' do
+      Util.deep_symbolize_keys({
+        item1: 'value1',
+        "item2" => 'value2',
+        hash: {
+          item3: 'value3',
+          "item4" => 'value4'
+        },
+        'array' => [{
+          "item5" => 'value5',
+          item6: 'value6'
+        }]
+      }).should == {
+        item1: 'value1',
+        item2: 'value2',
+        hash: {
+          item3: 'value3',
+          item4: 'value4'
+        },
+        array: [{
+          item5: 'value5',
+          item6: 'value6'
+        }]
+      }
+    end
+
+    it 'should work with numbers for keys' do
+      Util.deep_symbolize_keys({
+        "1" => "first",
+        "2" => "second"
+      }).should == {
+        :"1" => "first",
+        :"2" => "second"
+      }
+    end
+
+    it 'should skip nils and items that cant be symbolized' do
+      Util.deep_symbolize_keys({ nil => 'foo' }).should == { nil => 'foo' }
+    end
+
+    it 'should only munge hashes' do
+      Util.deep_symbolize_keys([]).should == []
+      Util.deep_symbolize_keys([{ 'foo' => 'bar' }]).should == [{ 'foo' => 'bar' }]
+    end
+  end
+end