I do not give my students a warm up on test days. I like them to have as much time as possible.
I always make two versions of a test and pass them out checkerboard style. I ask students to show work. I write by tests directly from the unit objective list located in the Practice Test in the review. This ensures that concepts get adequate coverage and the test covers what was actually taught.
This test was created with Kuta Software, an amazing resource for secondary mathematics teachers.
I offer a variety of Extra Credit puzzle for students who finish early and have no make up work to complete. This includes, but is not limited to; sudoku, mathdoku, logic problems, picture mazes, and pixel puzzles. A couple of my favorites are: Griddlers and Concept is puzzles
Both sites offer a number of free puzzles as well as purchasable books. Pixel Puzzle are a particular favorite. The Mathdoku are also great. They can increase a student's numeracy abilities if done regularly.