Draft: highlight where constant product differs from v1 and find out why

[katelynsills]

refs: #3716 (original constant product code with tests)
refs: #3771 (constant product code that got merged)

Description

This draft PR is to set up tests so that we can do a direct comparison of the constant product code and Uniswap v1. We're assuming that if the protocolFee is 0 and the price is not being "improved" or "reduced", the results should be the same. I'm getting different results. The file to look at is packages/zoe/test/unitTests/contracts/constantProduct/test-v1.js. I highlighted a particular test with test.only, but the other tests are failing too.

[katelynsills]

@dckc and @Chris-Hibbert, here's the differences I was seeing

[Chris-Hibbert]

We're assuming that if the protocolFee is 0 and the price is not being "improved" or "reduced", the results should be the same.

@katelynsills thinks the answers should be the same. I think they might be the same (in at least some cases, like getInputPrice vs. getOutputPrice), and it would be interesting to understand why they're different.

[katelynsills]

@katelynsills thinks the answers should be the same. I think they might be the same (in at least some cases, like getInputPrice vs. getOutputPrice), and it would be interesting to understand why they're different.

Good point, I forgot we had talked about that.

[dckc]

FWIW, I reproduced the results in a spreadsheet

as well as with yarn test.

[dckc]

oh... I didn't undo the "improved" stuff in my spreadsheet.

[Chris-Hibbert]

This code was all removed long ago.