There are a couple of ways to do this, but here's the one most people choose: 

1. Go to your old course. In the Course Menu, choose Course Tools > Tests, Surveys, and Pools. Choose Tests to open your Tests page.
2. Find the test you want to copy and click the down chevron to open the menu. Choose Export to Local Computer (there's also an option to Export to Content Collection, but it's usually more straightforward to just use your computer). 
3. The test will download to your computer as a .zip file. 
4. Now go to the course you want to copy the test to. Again, in your Course Menu, go to Course Tools > Tests, Surveys, and Pools and choose Tests to open the Tests page. 
5. Click on Import Test
6. Click on Browse Local Files to open a window where you can browse to find the .zip file you just downloaded. Select it, click Open, and then click Submit


The test will now show up on your Tests page, ready to be deployed.