Rain leaking through california room ceiling

Glad it rained heavily recently. Our 1 year builder warranty is expiring soon. Rain leaked through the roof over the california room. Water was dripping through the light fixtures, tracked down the exterior wall, down the wall into the sliding glass door, entered the framing and dripped inside the house.

We put in a service call but:

1. Since it doesn't rain a lot, how do I verify repairs?  Aim the garden hose over the roof? 
2. Can I get some kind of extended warranty/anything in writing in case it leaks next year or maybe this spring?
3. Say they repair the roof to prevent the leak. Do I need them to inspect the drywall over the sliding glass door?

TIA

I think you may have 10 years of coverage by the builder for the roof. I always walk around the 2nd floor during heavy rains to see if there are any issues.

Sometimes wind and rain would  get under the flashing guards especially if you have a vents on the roof and around the fire place chimney stacks. Check those areas.

Roof is most likely 10 years warranty. Get a moisture meter ( less than $30) and check everywhere.
Your builder will most likely get a restoration company and they should open walls up to inspect interior damages.

Is your property considered a Condo - Attached or Detached - then this could be an HOA issue as well as a builder repairable item.

Wouldn't hurt to check with neighbors to see how their home faired. Perhaps it's a design issue. Perhaps not. If it's a design / specific contractor issue then there may be a scaled up solution to be worked on.

Be sure to get everything in writing. Having dealt with a similar issue on a builder repair, it's amazing how much is immediately forgotten by some once the phone is hung up. You'll cut your headaches by 1/2 if you communicate by e-mail on this more than by phone.

Good luck with this!