fix(perp): Block users from opening infinite leverage positions

[matthiasmatt]

On the latest demo branch synced with master, we can open positions with 100k leverage:

>>> echo "guard cream sadness conduct invite crumble clock pudding hole grit liar hotel maid produce squeeze return argue turtle know drive eight casino maze host" | nibid keys add val --recover --keyring-backend test
>>> nibid tx perp open-position buy ubtc:unusd 100000 20 0 --from val --keyring-backend test --chain-id nibiru-localnet-0  --broadcast-mode block -y --gas 99999999999

This is not ideal. In the code we were not checking the validity of the margin ratio if the position is new.

[NibiruHeisenberg]

Can you double-check this test? How can the bad debt be positive but the PerpEF balance go up?

[matthiasmatt]

There's no bad debt created there. Changing the liquidation ratio from 100 to 10 removed it. To create bad debt I need to change the mark price after opening the position so the margin ratio is below the liquidation fee.

In this case, that means mocking the vpool GetSpotPrice function, which is exactly what's being done in the liquidate_unit_test.go functions

Should we remove those 2 bad debt tests? Since they are already checked there: liquidate_unit_test.go:374 / TestLiquidateIntoFullLiquidationWithBadDebt

[NibiruHeisenberg]

Ah I see, yeah in that case these two tests are redundant since TestLiquidateIntoFullLiquidationWithBadDebt should be covering them.

[AgentSmithMatrix]

I am not really a fan of using the leverage based on the margin ratio, but more into having a separate value for every pool. As in Binance, some pools allow you to open bigger leverage than others, and that is independent of the margin ratio.

[matthiasmatt]

I am not really a fan of using the leverage based on the margin ratio, but more into having a separate value for every pool. As in Binance, some pools allow you to open bigger leverage than others, and that is independent of the margin ratio.

I created an issue for that there: #781

[NibiruHeisenberg]

Ah I see, yeah in that case these two tests are redundant since TestLiquidateIntoFullLiquidationWithBadDebt should be covering them.