Every year ACT releases an official practice test that is provided to students as a sample test. Here I have listed links to six unique publicly disclosed tests released by ACT over the years. These are the only six unique tests released by ACT over the years, the rest are repeats of these same test forms.
Preparing for ACT 2018-19 (Form 1874FPRE): (PDF) Identical to 2017 April ACT (Form 74F)