Step 1. Make an enclosure in a forest. Make it pretty big (Mabye 30 by 50) I fenced mine off with fences.
Step 2. Put in a few saplings and [Important] Lots of torches. [\Important] This meant mobs that wolves like to eat will spawn at night. (Edit: As pointed out, saplings will, if grown make less spaces for the wolves to spawn... But they look pweeeety!)
Step 3. Decorate, I put in a small pond.
Step 4. Make it so that it is a one way thing to get into the fences. Kind of like:
Where stick is a fence.
Step 5. ???
Step 6. Profit.
I don't know whether this actually works and I am sorry if it doesn't work for you, but the wolves are "rare" and seven in one spot seems to say this works . I posted this for the people who cannot get wolves!
And if it doesn't work, at least you will have a nice garden .
Minecraft wiki said: