Merge pull request #16349 from jmcnevin/master

Correctly determine if migration is needed.

activerecord/lib/active_record/migration.rb

@@ -826,21 +826,20 @@ def schema_migrations_table_name
         SchemaMigration.table_name
       end
 
-      def get_all_versions
-        SchemaMigration.all.map { |x| x.version.to_i }.sort
+      def get_all_versions(connection = Base.connection)
+        if connection.table_exists?(schema_migrations_table_name)
+          SchemaMigration.all.map { |x| x.version.to_i }.sort
+        else
+          []
+        end
       end
 
       def current_version(connection = Base.connection)
-        sm_table = schema_migrations_table_name
-        if connection.table_exists?(sm_table)
-          get_all_versions.max || 0
-        else
-          0
-        end
+        get_all_versions(connection).max || 0
       end
 
       def needs_migration?(connection = Base.connection)
-        current_version(connection) < last_version
+        (migrations(migrations_paths).collect(&:version) - get_all_versions(connection)).size > 0
       end
 
       def last_version

activerecord/test/cases/migration_test.rb

@@ -75,6 +75,21 @@ def test_migrator_versions
     assert_equal 0, ActiveRecord::Migrator.current_version
     assert_equal 3, ActiveRecord::Migrator.last_version
     assert_equal true, ActiveRecord::Migrator.needs_migration?
+
+    ActiveRecord::SchemaMigration.create!(:version => ActiveRecord::Migrator.last_version)
+    assert_equal true, ActiveRecord::Migrator.needs_migration?
+  ensure
+    ActiveRecord::Migrator.migrations_paths = old_path
+  end
+
+  def test_migration_detection_without_schema_migration_table
+    ActiveRecord::Base.connection.drop_table :schema_migrations
+
+    migrations_path = MIGRATIONS_ROOT + "/valid"
+    old_path = ActiveRecord::Migrator.migrations_paths
+    ActiveRecord::Migrator.migrations_paths = migrations_path
+
+    assert_equal true, ActiveRecord::Migrator.needs_migration?
   ensure
     ActiveRecord::Migrator.migrations_paths = old_path
   end