Potential issue with `testPathIndependenceForSwaps` test from part 3/4 about echidna-streaming-series

[technovision99]

The test doesn't concern the fees taken by uniswap, which is 0.30%, not 3%. The test attempts to test the invariant "swapping X for Y and back should leave the user with X tokens" (bar some precision loss, currently set to 3%). So I believe the test is correct, although it's interesting you found an edge case where this doesn't hold. Could you zip and send your corpus? This might have to do with the pool conditions being strange (it seems there's low and imbalanced liquditity judging from the call sequence, but I'm not 100% sure)

[aviggiano]

Thank you for your response, I stand corrected.

About 3%, was this precision loss defined? Just empirically?

About the corpus, I actually changed a bunch of stuff on the tests, so maybe this won't work out of the box. I'll try to repro on this repo and will send it here if I'm able to do it.

[technovision99]

Yeah the precision loss is defined empirically. I'm not sure if there's any specification that could detail the potential precision loss, but I think 3% is a generous bound given that only a 0.3% fee is taken from each swap. I also think this is a good number to use because it's generally the recommended slippage tolerance