valid_type? should accept only supported types

[kamipo]

valid_type? is used in schema dumper to determine if a type is
supported. So if valid_type?(:foobar) is true, it means that schema
dumper is allowed to create t.foobar. But it doesn't work. I think
that valid_type? should accept only supported types.

https://github.com/rails/rails/blob/v5.1.0.beta1/activerecord/lib/active_record/schema_dumper.rb#L135-L142

  columns.each do |column|
    raise StandardError, "Unknown type '#{column.sql_type}' for column '#{column.name}'" unless @connection.valid_type?(column.type)
    next if column.name == pk
    type, colspec = @connection.column_spec(column)
    tbl.print "    t.#{type} #{column.name.inspect}"
    tbl.print ", #{format_colspec(colspec)}" if colspec.present?
    tbl.puts
  end

[rafaelfranca]

hmmm, this is going in the opposite direction that the comment on activerecord/test/cases/adapters/sqlite3/sqlite3_adapter_test.rb . Did you check why it was made that way?

[kamipo]

Yes, the comment added at #9984 (related #9204, #9656) but it is incorrect I think. Even though sqlite database supports any sql_types, schema dumper is not. valid_type? checks type, not sql_type. valid_type?(:foobar) should not be accepted. :foobar is not a valid type for schema dumper.