Rails 6.1: Coerce schema cache test to handle Time marshal in ruby 2.5 and 2.6

[mgrunberg]

This PR fixes:

ActiveRecord::ConnectionAdapters::SchemaCacheTest#test_marshal_dump_and_load_via_disk:
ArgumentError: year too big to marshal: 1753 UTC

ActiveRecord::ConnectionAdapters::SchemaCacheTest#test_marshal_dump_and_load_with_gzip:
ArgumentError: year too big to marshal: 1753 UTC

Those errors only exists in ruby 2.5 and 2.6 runs

Context

Rails 6.1 adds support for marshal as a schema cache serialization strategy (rails/rails@9a356fc)

Ruby 2.5 and Ruby 2.6 have a bug that prevents them to marshal Time instances before 1900 (see https://bugs.ruby-lang.org/issues/15160). The issue is not present on 2.7. Found the link looking at rails/rails#41075.

sst_datatypes table has a datetime column with default 1753-01-01T00:00:00.123. The table is created here https://github.com/rails-sqlserver/activerecord-sqlserver-adapter/blob/main/test/schema/datatypes/2012.sql#L27.

Possible solutions

1. update 2012.sql and change default to something else.

That file has been around for a while. I can't tell why 1753-01-01T00:00:00.123 was picked. For example, I can't tell if it's covering some specific scenario.

2. coerce the test

change the default value just for the failing test and rubies.

3. cast default value to something different than Time

Haven't thought/investigate this path but felt that would lead to issues.

I choose the second option

[aidanharan]

I'd be inclined just to change the year to something 1900+. Can't see anything in the original commit to indicate why 1753 was picked 3fb340c

[mgrunberg]

I'm starting to think that '1753-01-01T00:00:00.123' was picked because is the minimum valid value for datetime columns.

According to docs (https://docs.microsoft.com/en-us/sql/t-sql/data-types/datetime-transact-sql?view=sql-server-ver15) datetime columns goes from 1753-01-01 00:00:00 to 9999-12-31 23:59:59.997

2012.sql has a smalldatetime with 1900-01-01 00:00:00, which is the min value.

If this is the case, keeping 1753-01-01T00:00:00.123 feels correct.

[aidanharan]

Considering that Ruby 2.5 had already reached EOL and Ruby 2.6 reaches EOL in 2022-03-31 (https://www.ruby-lang.org/en/downloads/branches/) I think it's fine to coerce the tests as you've done.