Move calendar test down to unit tests

Remove tests that are specific to the calendar model from controller
test and move them to unit tests.

test/models/todos/calendar_test.rb

@@ -0,0 +1,47 @@
+require_relative '../../test_helper'
+
+module Todos
+  class CalendarTest < ActiveSupport::TestCase
+
+    def setup
+      @calendar = Calendar.new(users(:admin_user))
+      Todo.destroy_all
+    end
+
+    def create_todo(due_date)
+      Todo.create due: due_date,
+        user: users(:admin_user),
+        description: 'Test Todo',
+        context: Context.first
+    end
+
+    def test_due_today
+      due_today = create_todo(Time.zone.now)
+
+      assert_equal [due_today], @calendar.due_today
+    end
+
+    def test_due_this_week
+      due_this_week = create_todo(Time.zone.now.end_of_week)
+      assert_equal [due_this_week], @calendar.due_this_week
+    end
+
+    def test_due_next_week
+      due_next_week = create_todo(1.week.from_now.beginning_of_day)
+
+      assert_equal [due_next_week], @calendar.due_next_week
+    end
+
+    def test_due_this_month
+      due_this_month = create_todo(Time.zone.now.end_of_month)
+
+      assert_equal [due_this_month], @calendar.due_this_month
+    end
+
+    def test_due_after_this_month
+      due_after_this_month = create_todo(1.month.from_now)
+      assert_equal [due_after_this_month], @calendar.due_after_this_month
+    end
+  end
+end
+