BURs: impose a maximum size limit on BURs.

Enforce a maximum size limit of 100 lines per BUR. Larger BURs should be
split into smaller chunks.

app/logical/bulk_update_request_processor.rb

@@ -1,5 +1,6 @@
 class BulkUpdateRequestProcessor
   MAXIMUM_RENAME_COUNT = 200
+  MAXIMUM_SCRIPT_LENGTH = 100
 
   include ActiveModel::Validations
 
@@ -8,6 +9,7 @@ class BulkUpdateRequestProcessor
   attr_reader :bulk_update_request
   delegate :script, :forum_topic, to: :bulk_update_request
   validate :validate_script
+  validate :validate_script_length
 
   def initialize(bulk_update_request)
     @bulk_update_request = bulk_update_request
@@ -109,6 +111,12 @@ class BulkUpdateRequestProcessor
     end
   end
 
+  def validate_script_length
+    if commands.size > MAXIMUM_SCRIPT_LENGTH
+      errors[:base] << "Bulk update request is too long (maximum size: #{MAXIMUM_SCRIPT_LENGTH} lines). Split your request into smaller chunks and try again."
+    end
+  end
+
   def process!(approver)
     ActiveRecord::Base.transaction do
       commands.map do |command, *args|

test/unit/bulk_update_request_test.rb

@@ -373,6 +373,15 @@ class BulkUpdateRequestTest < ActiveSupport::TestCase
           assert_equal(["Can't create implication a -> b ('a' must have a wiki page; 'b' must have a wiki page)"], @bur.errors.full_messages)
         end
       end
+
+      context "a bulk update request that is too long" do
+        should "fail" do
+          @bur = build(:bulk_update_request, script: "nuke touhou\n" * 200)
+
+          assert_equal(false, @bur.valid?)
+          assert_equal(["Bulk update request is too long (maximum size: 100 lines). Split your request into smaller chunks and try again."], @bur.errors.full_messages)
+        end
+      end
     end
 
     context "when the script is updated" do