Push db schema cache dump into schema cache class

activerecord/lib/active_record/connection_adapters/schema_cache.rb

@@ -129,6 +129,12 @@ def clear_data_source_cache!(name)
         @indexes.delete name
       end
 
+      def dump_to(filename)
+        clear!
+        connection.data_sources.each { |table| add(table) }
+        open(filename, "wb") { |f| f.write(YAML.dump(self)) }
+      end
+
       def marshal_dump
         # if we get current version during initialization, it happens stack over flow.
         @version = connection.migration_context.current_version

activerecord/lib/active_record/tasks/database_tasks.rb

@@ -449,9 +449,7 @@ def load_seed
       # ==== Examples:
       #   ActiveRecord::Tasks::DatabaseTasks.dump_schema_cache(ActiveRecord::Base.connection, "tmp/schema_dump.yaml")
       def dump_schema_cache(conn, filename)
-        conn.schema_cache.clear!
-        conn.data_sources.each { |table| conn.schema_cache.add(table) }
-        open(filename, "wb") { |f| f.write(YAML.dump(conn.schema_cache)) }
+        conn.schema_cache.dump_to(filename)
       end
 
       def clear_schema_cache(filename)

activerecord/test/cases/connection_adapters/schema_cache_test.rb

@@ -16,13 +16,15 @@ def test_primary_key
       end
 
       def test_yaml_dump_and_load
-        @cache.columns("posts")
-        @cache.columns_hash("posts")
-        @cache.data_sources("posts")
-        @cache.primary_keys("posts")
-        @cache.indexes("posts")
+        # Create an empty cache.
+        cache = SchemaCache.new @connection
+
+        tempfile = Tempfile.new(["schema_cache-", ".yml"])
+        # Dump it. It should get populated before dumping.
+        cache.dump_to(tempfile.path)
 
-        new_cache = YAML.load(YAML.dump(@cache))
+        # Reload it.
+        new_cache = YAML.load(File.read(tempfile.path))
         assert_no_queries do
           assert_equal 12, new_cache.columns("posts").size
           assert_equal 12, new_cache.columns_hash("posts").size
@@ -31,6 +33,8 @@ def test_yaml_dump_and_load
           assert_equal 1, new_cache.indexes("posts").size
           assert_equal @database_version.to_s, new_cache.database_version.to_s
         end
+      ensure
+        tempfile.unlink
       end
 
       def test_yaml_loads_5_1_dump