Hey Xavier,
I'm well past most of the things you outlined. I do have to test the output
because, as usual, the SQL Server adapter has to jump thru a few hoops to get
things working and I want to black box test the final output of that behavior.
Our parameterized SQL is a formatted string to a stored procedure called
sp_executesql, details here.
http://www.engineyard.com/blog/2011/sql-server-10xs-faster-with-rails-3-1/
Because SQL Server's show plan (explain) needs the unprepared statement, our
implementation has to (1) method chain ActiveRecord::Explain#exec_explain to
parse the unquoted first arg of the previous query now formatted with
sp_executesql and (2) write a simple case inside our #exec_query that replaces
the parameters with the binds when an EXPLAIN sql name is happening. All in all
I am happy with our little hacks, but just wanted a nice way to test that we
are generating an "explain" plan properly.
I have tests for simple stuff that does not have binds, but wanted to write a
test for something like `with_threshold(0) { Car.find(1) }` which does leverage
a bind parameter but only logs to ActiveRecord's logger. So basically, I was
looking for a nice way to do that which would make sure I was testing at a high
level all the low level hacks.
- Ken
On Dec 31, 2011, at 5:29 PM, Xavier Noria wrote:
> On Sat, Dec 31, 2011 at 10:59 PM, Ken Collins <[email protected]> wrote:
>
>> I've been getting the SQL Server adapter up to passing for 3.2 and I wanted
>> to test our explain printer. It will be very much like mysql2's printer. But
>> I think my brain is mush and my meta-fu weak at the moment and I need some
>> help. I tried stubbing ActiveRecord::Base.logger.warn but to no avail. Any
>> thoughts?
>
> Fantastic!
>
> The high-level API is implemented in Active Record. You do not need to
> test via the logger, at the adapter level you only need to write
> #explain, which should return a string[*], and test that very return
> value. Just ensure the string itself is correct.
>
> The caller code takes that string and does stuff with it, but that's
> handled above and it's tested in Active Record itself in an agnostic
> way.
>
> For example, this is the implementation in the SQLite adapter:
>
>
> https://github.com/rails/rails/blob/master/activerecord/lib/active_record/connection_adapters/sqlite_adapter.rb#L219-236
>
> and these are its tests:
>
>
> https://github.com/rails/rails/blob/master/activerecord/test/cases/adapters/sqlite3/explain_test.rb
>
> Your adapter should do something like that.
>
> Remember also to define a predicate #supports_explain? that returns true.
>
> Hope that helps, please write again if more questions arise.
>
> Xavier
>
> [*] This string should ideally be a carbon copy of the one users are
> familiar with. I don't know if that makes sense for SQL Server, maybe
> they are used to some GUI output there?
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