You focus to much on your images, you say that this was a test shoot to show them what images you can produce.
I think you forget one big thing. This is also a test shoot to show them how you will be to work with.
Threat any free shoot as you would a paid shoot except the money changing hands.
I am not a fan of giving away images, but in some cases and in this case you say it is a test shoot to show them how you work and that you can deliver same quality time after time. I would think that the right way to do it is as magnum808 says. Try seeing things from the other side of table.
If they still want free images from you after 1-3 freeshoots, then I would be worried about beeing used. If they wont pay you after these shoots, then I would not work for them again. Maybe they finds another photographer to do the next shoots for free, but if they want concistency and quality work, like they probably want. They will pay for it when they know what they get.
I would edit the best images and give it to them as soon as possible without more hassle.
When the client say all the images, they don't really want all, but all the good ones. And if you tell them there were 4 good ones from a shoot of maybe 100? that will also tell them something.
Just my thoughts trying to see it from the other side of the table, without any experience in photography business, but it cant be that different from other businesses