If you don't have a specific test in mind, put in words that describe your interests, combined with words like (test* or assessment* or survey* or instrument* or evaluation* or measure* or questionnaire* or scale*). This will find a mixture of results-- some articles whose authors used a test but don't include it, and some that do. Not finding what you need? Use alternative words to describe what you are looking for--the thesaurus shows preferred terms, called subjects or descriptors. Have the name of a specific test? Use it--you should get citations to articles whose authors used the test and may get commentary as well.
If you put in a descriptive term such as depression in one of the search boxes, and then put the word appended in the next search box and choose "tests and measures" from the dropdown menu for that search box, you should retrieve articles that have the particular test or measure attached to the article.This works most of the time.
Alternatively, you may type in the title of a test with the word appended at the end of the search box line, such as smoking cessation appended, and then choose tests and measures from the dropdown menu of that search box.
If you use the classification codes in the 222x series, such as 2224 Clinical Psychological testing to limit your search, you can find articles about tests or measures of that type. You may choose these codes from the limits box or type them in with the search, in the form xxxx in the search box and then choosing CC from the dropdown menu. For example, 2227 is Educational measurement.