Check if the test/measure is published by searching for it in these resources. If a test is published it is usually available for purchase through the publisher and not in the library collection.
Unpublished tests, measures, scales and other instruments can easily be found using the same techniques you would use to research other part of your topic, that is, through the literature. Many unpublished tests appear in journals and can be found through databases.
The best part is, it is often possible to get a copy of an unpublished test! Don't forget that we can ILL an article for you! Ask us!
Once you have a test's name, a search engine like Google can be a good place to check if the test is freely available online.