Fix GH #4674. Reset column information and sequence name when setting table_name.

[kennyj]

In now implementation, when calling table_name=, we reset @quoted_table_name, @arel_table, but we don't reset column information and sequence name.

Please see #4674 .

BTW, the original issue was happen on 3-2-stable.

[josevalim]

/cc @jonleighton

[jonleighton]

@kennyj I am concerned about wiping out @sequence_name. What if the user does:

class Foo < AR::Base
  self.sequence_name = "omg"
  self.table_name    = "lol" # sequence name is now wiped
end

I guess we probably need to get track of any explicitly set sequence name, separately from the cached sequence name value, can you look at that?

Thanks

[kennyj]

@jonleighton OK. I'll look at that.

[kennyj]

@jonleighton Rebased and updated !

Please review it. If necessary, I'll squash commits.

[ebeigarts]

Can somebody explain why there is a unless before_seq.blank? && after_seq.blank? in test assertion?

I think something is wrong here, sequence_name now returns false, since reset_sequence_name now returns always false and it is assigned to @sequence_name.

model_schema.rb#L168:

@sequence_name ||= reset_sequence_name

[kennyj]

@ebeigarts Thanks ! I was wrong, and I'll fix it.

BTW: unless before_seq.blank? && after_seq.blank? means that sequence is supported ;-)

[kennyj]

I sent a PR #5832. Thanks :-)