BlinkyBill:
There is an absolute defence to the brightline test (which came in in 2015, from memory), which is if the house is your primary residence then the test does not apply, and no capital gain is applicable.
If the house is not your primary residence, then the test applies.
So If I reno'ed the house I live in and sold it every year, I would not get nabbed as running an income generating business over time?