According to a spec sheet I have, Ontario has a ASM 2525 and Two speed idle test for light duty vehicles 4 years old to 19 years old. ASM 2525 means the dyno is loaded to 25% of the vehicles total weight and emissions results are recorded. The ASM 2525 is mainly a Nox test. Then apparently the emissions are also tested at idle and 2500 rpm no no load. If you have an open loop chip, you'll probably fail the idle test. If your cat is missing, you may fail HC and CO (for ASM2525), especially if the cutpoints are a maximum EPA regulation. Depending on the Nox cutpoint, if your EGR system is not working properly, you may fail Nox on the ASM 2525 test. Also, looks like there is some sort of visual inspection.
I don't live in Ontario, this is just what is in their spec sheet. Hope this helps.