expand migration paths before requiring them. [#4240 state:resolved]

Signed-off-by: wycats <wycats@gmail.com>

2 files changed, 14 insertions, 1 deletions

diff --git a/activerecord/lib/active_record/migration.rb b/activerecord/lib/active_record/migration.rb
index 23e4505f61..d4cda927ad 100644
--- a/activerecord/lib/active_record/migration.rb
+++ b/activerecord/lib/active_record/migration.rb
@@ -374,7 +374,7 @@ module ActiveRecord
       end
 
       def load_migration
-        require(filename)
+        require(File.expand_path(filename))
         name.constantize
       end
 
diff --git a/activerecord/test/cases/migration_test.rb b/activerecord/test/cases/migration_test.rb
index 03ee8dcf3c..e213986ede 100644
--- a/activerecord/test/cases/migration_test.rb
+++ b/activerecord/test/cases/migration_test.rb
@@ -1104,6 +1104,19 @@ if ActiveRecord::Base.connection.supports_migrations?
       assert_equal migrations[0].name, 'InnocentJointable'
     end
 
+    def test_relative_migrations
+      $".delete_if do |fname|
+        fname == (MIGRATIONS_ROOT + "/valid/1_people_have_last_names.rb")
+      end
+      Object.send(:remove_const, :PeopleHaveLastNames)
+
+      Dir.chdir(MIGRATIONS_ROOT) do
+        ActiveRecord::Migrator.up("valid/", 1)
+      end
+
+      assert defined?(PeopleHaveLastNames)
+    end
+
     def test_only_loads_pending_migrations
       # migrate up to 1
       ActiveRecord::Migrator.up(MIGRATIONS_ROOT + "/valid", 1)