Add callback on skipped migration while copying migrations

activerecord/lib/active_record/migration.rb

@@ -384,23 +384,32 @@ def method_missing(method, *arguments, &block)
         end
       end
 
-      def copy(destination, sources)
+      def copy(destination, sources, options = {})
         copied = []
 
+        destination_migrations = ActiveRecord::Migrator.migrations(destination)
+        last = destination_migrations.last
         sources.each do |name, path|
-          destination_migrations = ActiveRecord::Migrator.migrations(destination)
           source_migrations = ActiveRecord::Migrator.migrations(path)
-          last = destination_migrations.last
 
           source_migrations.each do |migration|
-            next if destination_migrations.any? { |m| m.name == migration.name }
+            source = File.read(migration.filename)
+            source = "# This migration comes from #{name} (originally #{migration.version})\n#{source}"
+
+            if duplicate = destination_migrations.detect { |m| m.name == migration.name }
+              options[:on_skip].call(name, migration) if File.read(duplicate.filename) != source && options[:on_skip]
+              next
+            end
 
             migration.version = next_migration_number(last ? last.version + 1 : 0).to_i
+            new_path = File.join(destination, "#{migration.version}_#{migration.name.underscore}.rb")
+            old_path, migration.filename = migration.filename, new_path
             last = migration
 
-            new_path = File.join(destination, "#{migration.version}_#{migration.name.underscore}.rb")
-            FileUtils.cp(migration.filename, new_path)
-            copied << new_path
+            FileUtils.cp(old_path, migration.filename)
+            copied << migration
+            options[:on_copy].call(name, migration, old_path) if options[:on_copy]
+            destination_migrations << migration
           end
         end
 
@@ -426,6 +435,10 @@ def initialize(name, version, filename)
       @migration = nil
     end
 
+    def basename
+      File.basename(filename)
+    end
+
     delegate :migrate, :announce, :write, :to=>:migration
 
     private

activerecord/test/cases/migration_test.rb

@@ -1912,7 +1912,7 @@ def test_copying_migrations_without_timestamps
       copied = ActiveRecord::Migration.copy(@migrations_path, {:bukkits => MIGRATIONS_ROOT + "/to_copy"})
       assert File.exists?(@migrations_path + "/4_people_have_hobbies.rb")
       assert File.exists?(@migrations_path + "/5_people_have_descriptions.rb")
-      assert_equal [@migrations_path + "/4_people_have_hobbies.rb", @migrations_path + "/5_people_have_descriptions.rb"], copied
+      assert_equal [@migrations_path + "/4_people_have_hobbies.rb", @migrations_path + "/5_people_have_descriptions.rb"], copied.map(&:filename)
 
       files_count = Dir[@migrations_path + "/*.rb"].length
       copied = ActiveRecord::Migration.copy(@migrations_path, {:bukkits => MIGRATIONS_ROOT + "/to_copy"})
@@ -1953,7 +1953,7 @@ def test_copying_migrations_with_timestamps
         assert File.exists?(@migrations_path + "/20100726101011_people_have_descriptions.rb")
         expected = [@migrations_path + "/20100726101010_people_have_hobbies.rb",
                     @migrations_path + "/20100726101011_people_have_descriptions.rb"]
-        assert_equal expected, copied
+        assert_equal expected, copied.map(&:filename)
 
         files_count = Dir[@migrations_path + "/*.rb"].length
         copied = ActiveRecord::Migration.copy(@migrations_path, {:bukkits => MIGRATIONS_ROOT + "/to_copy_with_timestamps"})
@@ -2006,6 +2006,24 @@ def test_copying_migrations_with_timestamps_to_destination_with_timestamps_in_fu
       clear
     end
 
+    def test_skipping_migrations
+      @migrations_path = MIGRATIONS_ROOT + "/valid_with_timestamps"
+      @existing_migrations = Dir[@migrations_path + "/*.rb"]
+
+      sources = ActiveSupport::OrderedHash.new
+      sources[:bukkits] = sources[:omg] = MIGRATIONS_ROOT + "/to_copy_with_timestamps"
+
+      skipped = []
+      on_skip = Proc.new { |name, migration| skipped << "#{name} #{migration.name}" }
+      copied = ActiveRecord::Migration.copy(@migrations_path, sources, :on_skip => on_skip)
+      assert_equal 2, copied.length
+
+      assert_equal 2, skipped.length
+      assert_equal ["bukkits PeopleHaveHobbies", "bukkits PeopleHaveDescriptions"], skipped
+    ensure
+      clear
+    end
+
     def test_copying_migrations_to_empty_directory
       @migrations_path = MIGRATIONS_ROOT + "/empty"
       @existing_migrations = []