Refactor microsecond precision to be database agnostic

The various databases don't actually need significantly different
handling for this behavior, and they can achieve it without knowing
about the type of the object.

The old implementation was returning a string, which will cause problems
such as breaking TZ aware attributes, and making it impossible for the
adapters to supply their logic for time objects.

2 files changed, 4 insertions, 14 deletions

diff --git a/activerecord/test/cases/adapters/mysql2/connection_test.rb b/activerecord/test/cases/adapters/mysql2/connection_test.rb
index d261e2db55..ff8ce93248 100644
--- a/activerecord/test/cases/adapters/mysql2/connection_test.rb
+++ b/activerecord/test/cases/adapters/mysql2/connection_test.rb
@@ -122,11 +122,4 @@ class MysqlConnectionTest < ActiveRecord::TestCase
   ensure
     @connection.execute "DROP TABLE `bar_baz`"
   end
-
-  if mysql_56?
-    def test_quote_time_usec
-      assert_equal "'1970-01-01 00:00:00.000000'", @connection.quote(Time.at(0))
-      assert_equal "'1970-01-01 00:00:00.000000'", @connection.quote(Time.at(0).to_datetime)
-    end
-  end
 end
diff --git a/activerecord/test/cases/adapters/mysql2/datetime_test.rb b/activerecord/test/cases/adapters/mysql2/datetime_test.rb
index ae00f4e131..7a37247d6a 100644
--- a/activerecord/test/cases/adapters/mysql2/datetime_test.rb
+++ b/activerecord/test/cases/adapters/mysql2/datetime_test.rb
@@ -4,15 +4,12 @@ if mysql_56?
   class DateTimeTest < ActiveRecord::TestCase
     self.use_transactional_fixtures = false
 
-    class Foo < ActiveRecord::Base; end
-
-    def test_default_datetime_precision
-      ActiveRecord::Base.connection.create_table(:foos, force: true)
-      ActiveRecord::Base.connection.add_column :foos, :created_at, :datetime
-      ActiveRecord::Base.connection.add_column :foos, :updated_at, :datetime
-      assert_nil activerecord_column_option('foos', 'created_at', 'precision')
+    teardown do
+      ActiveRecord::Base.connection.drop_table(:foos, if_exists: true)
     end
 
+    class Foo < ActiveRecord::Base; end
+
     def test_datetime_data_type_with_precision
       ActiveRecord::Base.connection.create_table(:foos, force: true)
       ActiveRecord::Base.connection.add_column :foos, :created_at, :datetime, precision: 1