There are several types of tests you may encounter. Most assessments will include more than one type of test. The problem with using only an intelligence test is that it can have adverse impact on protected groups of people. The reasons for this are complex and not entirely understood, but in order to avoid lawsuits and to increase the predictive power of testing, most employers will use intelligence tests in conjunction with other types of tests. Knowing that is an edge in itself.
Personality tests are also very popular with employers.
These tests can be very long and will usually ask you to rate the extent to which a statement applies to you or to select your preference from pairs of options. Some of these questions might seem odd and unrelated to employment. Often, people try to select the answers that will show them in the best light. Test writers have anticipated this and most personality tests will include some sort of 'lie scale' that will catch you if you try to make yourself seem too wonderful. There are a few ways to think about personality tests.