After you run a few games, homebrew your own campaign. Make sure the 150-300 pages of house rules are bound in hardcover- at least for yourself- and get some copies to your players. Insist they read them all.
No, there won’t be a written test, but as DM, you’ll easily be able to man the players into situations where mastery of the house rules will be important. Maybe even life or death…
NOTE: while I have been known to hand out house rule “bibles or campaign setting overviews, most were brief- typically no more than 5 pages. The biggest I ever did was 10+, but that was for a RIFTS campaign, and most of it was devoted to a list of OCCs & RCCs allowed for play, with a 1-2 sentence descriptor and sourcebook page number.