Make the migration generator handle pre-existing migrations with the …

…same timestamp.

In the event a migration already exists with that number, the new migration's timestamp will be incremented by 1.

[#4412 state:resolved]

Signed-off-by: Michael Koziarski <michael@koziarski.com>

activerecord/lib/rails/generators/active_record.rb

@@ -19,10 +19,11 @@ def self.source_root
       # Implement the required interface for Rails::Generators::Migration.
       #
       def self.next_migration_number(dirname) #:nodoc:
+        next_migration_number = current_migration_number(dirname) + 1
         if ActiveRecord::Base.timestamped_migrations
-          Time.now.utc.strftime("%Y%m%d%H%M%S")
+          [Time.now.utc.strftime("%Y%m%d%H%M%S"), "%.14d" % next_migration_number].max
         else
-          "%.3d" % (current_migration_number(dirname) + 1)
+          "%.3d" % next_migration_number
         end
       end
     end

railties/test/generators/migration_generator_test.rb

@@ -10,6 +10,19 @@ def test_migration
     assert_migration "db/migrate/#{migration}.rb", /class ChangeTitleBodyFromPosts < ActiveRecord::Migration/
   end
 
+  def test_migrations_generated_simultaneously
+    migrations = ["change_title_body_from_posts", "change_email_from_comments"]
+
+    first_migration_number, second_migration_number = migrations.collect do |migration|
+      run_generator [migration]
+      file_name = migration_file_name "db/migrate/#{migration}.rb"
+
+      File.basename(file_name).split('_').first
+    end
+
+    assert_not_equal first_migration_number, second_migration_number
+  end
+
   def test_migration_with_class_name
     migration = "ChangeTitleBodyFromPosts"
     run_generator [migration]