fix: add pre-k to list of grades

app/presenters/analyze/graph/column/grade/p_k.rb

@@ -0,0 +1,33 @@
+# frozen_string_literal: true
+
+module Analyze
+  module Graph
+    module Column
+      module Grade
+        class PK < GroupedBarColumnPresenter
+          include Analyze::Graph::Column::Grade::ScoreForGrade
+          include Analyze::Graph::Column::Grade::GradeCount
+          def label
+            %w[Pre-K]
+          end
+
+          def basis
+            "student"
+          end
+
+          def show_irrelevancy_message?
+            false
+          end
+
+          def show_insufficient_data_message?
+            false
+          end
+
+          def grade
+            -1
+          end
+        end
+      end
+    end
+  end
+end

app/presenters/analyze/graph/students_by_grade.rb

@@ -34,6 +34,8 @@ module Analyze
       end
 
       CFR = {
+        -1 => PK,
+        0 => Zero,
         1 => One,
         2 => Two,
         3 => Three,
@@ -45,8 +47,9 @@ module Analyze
         9 => Nine,
         10 => Ten,
         11 => Eleven,
-        12 => Twelve,
+        12 => Twelve
       }.freeze
     end
   end
 end
+