Loan Contract #1903

katelynsills · 2020-10-22T21:03:18Z

Adds a basic loan contract using a priceAuthority, with tests.

Add collateral of a particular brand and get a loan of another brand. Collateral (as known as margin) must be greater than the loan value, at an amount set by the Maintenance Margin Requirement (mmr) in the terms of the contract. The loan does not have a distinct end time. Rather, if the value of the collateral changes such that insufficient margin is provided, the collateral is liquidated, and the loan is closed. At any time, the borrower can add collateral or repay the loan with interest, closing the loan.

The borrower can set up their own margin calls by getting the priceAuthority from the terms and calling E(priceAuthority).quoteWhenLT(allCollateral, x) where x is the value of the collateral in the Loan brand at which they want a reminder to addCollateral.

Note that all collateral must be of the same brand and all of the
loaned amount and interest must be of the same (separate) brand.

Terms:

mmr (default = 150) - the Maintenance Margin Requirement, in
percent. The default is 150, meaning that collateral should be
worth at least 150% of the loan. If the value of the collateral
drops below mmr, liquidation occurs.
priceAuthority - will be used for getting the current value of
collateral and setting liquidation triggers.
autoswapInstance - The running contract instance for an Autoswap
or Multipool Autoswap installation. The publicFacet of the
instance is used for producing an invitation to sell the
collateral on liquidation.
periodAsyncIterable - the asyncIterable used for notifications
that a period has passed, on which compound interest will be
calculated using the interestRate.
interestRate - the rate in basis points that will be multiplied
with the debt on every period to compound interest.

IssuerKeywordRecord:
Keyword: 'Collateral' - The issuer for the digital assets to be
escrowed as collateral.
Keyword: 'Loan' - The issuer for the digital assets to be loaned
out.

Closes #1942
Closes #1939

Chris-Hibbert

This is nicely structured. I appreciate all the distinct source files, each well-commented.

This looks like a good approach. The main thing (other than just unfinished stuff) is that when liquidation is triggered, or the collateral changes, the code needs to recalculate the trigger levels and reschedule the trigger.

I've finished reading the contract code, and have the types and tests still to read.

packages/zoe/src/contracts/loan/lend.js

packages/zoe/src/contracts/loan/borrow.js

packages/zoe/src/contracts/loan/addCollateral.js

packages/zoe/src/contracts/loan/close.js

packages/zoe/src/contracts/loan/liquidate.js

katelynsills · 2020-10-28T01:53:29Z

This looks like a good approach. The main thing (other than just unfinished stuff) is that when liquidation is triggered, or the collateral changes, the code needs to recalculate the trigger levels and reschedule the trigger.

Oh good catch, I will fix

rowgraus · 2020-10-28T18:50:44Z

Remaining to-do: address liquidations re: comments from @Chris-Hibbert

packages/zoe/test/unitTests/contracts/loan/test-loan-e2e.js

rowgraus · 2020-11-04T20:03:04Z

Adjust to allow loan to take mocked price from Chainlink instead of internal autoswap price authority

Chris-Hibbert

mostly minor enhancements to doc or type info.

I suggest a few additional tests, some of which might point to code that doesn't exist. Would you look at these and see if any are needed before people start using the contract?

packages/zoe/src/contracts/loan/index.js

Chris-Hibbert · 2020-11-05T19:43:03Z

packages/zoe/test/fakePriceAuthority.js

+    // TODO: implement
+    getPriceNotifier: () => {
+      const { notifier } = makeNotifierKit();
+      return notifier;
+    },


This has been added in #1985.

Looks like your version will get in first, and I'll integrate when I merge 1985.

packages/zoe/src/contracts/loan/close.js

packages/zoe/src/contracts/loan/scheduleLiquidation.js

packages/zoe/src/contracts/loan/borrow.js

packages/zoe/test/unitTests/contracts/loan/helpers.js

packages/zoe/test/unitTests/contracts/loan/test-lend.js

Chris-Hibbert · 2020-11-05T21:34:11Z

packages/zoe/test/unitTests/contracts/loan/test-liquidate.js

+
+import { trade } from '../../../../src/contractSupport';
+
+test('test doLiquidation with mocked autoswap', async t => {


additional test:

autoswap fails

multiple scheduled liquidations don't interfere

'Multiple scheduled liquidations' is already tested.

For 'autoswap fails' - do you mean the trade fails? That is not tested.

Sorry, I don't see a test that verifies that the two liquidations from an initial borrow and adding collateral don't interfere. Which test are you referring to?

For 'autoswap fails' - do you mean the trade fails?

Yeah, with autoswap, that pair might not have been initialized, or all the collateral could have been removed. There's no guarantee that autoswap will always succeed. Particularly in the start-up sequence, it's conceivable that a pair of currencies could be missing.

Sorry, I don't see a test that verifies that the two liquidations from an initial borrow and adding collateral don't interfere. Which test are you referring to?

'borrow, then addCollateral, then getLiquidationPromise'

Chris-Hibbert · 2020-11-05T21:37:59Z

packages/zoe/test/unitTests/contracts/loan/test-addCollateral.js

+  performAddCollateral,
+} from './helpers';
+
+test.todo('makeAddCollateralInvitation - test bad proposal');


additionally:

can we verify that a new liquidation trigger was rescheduled?

Yes, that is tested already.

See 'borrow, then addCollateral, then getLiquidationPromise'

That tests ends with t.falsy(liquidated);, so I think it shows that neither was triggered. I'm interested in the case where both price levels are exceeded, but only the rescheduled one should cause liquidation.

value is at 12
borrow 100 with 16 of collateral. (12 * 16 > 1.5 * 100)
value goes to 10 (10 * 16 > 1.5 * 100)
addCollateral of 10
value goes to 8; with 16 collateral, would have liquidated (8 * 16 < 1.5 * 100)
value goes to 5; now we should actually liquidate. (5 * 26 < 1.5 * 100)

Oh, good point. That liquidated is old - the liquidation code doesn't call that anymore. Let me revise that test.

Liquidation is added to that test

packages/zoe/test/unitTests/contracts/loan/test-loan-e2e.js

katelynsills · 2020-11-06T02:24:41Z

@Chris-Hibbert Ready for another review

Chris-Hibbert

Thanks for the updates. This looks good now.

packages/zoe/src/contracts/loan/liquidate.js

Chris-Hibbert · 2020-11-06T04:56:36Z

packages/zoe/test/fakePriceAuthority.js

+    // TODO: implement
+    getPriceNotifier: () => {
+      const { notifier } = makeNotifierKit();
+      return notifier;
+    },


Looks like your version will get in first, and I'll integrate when I merge 1985.

Co-authored-by: Chris Hibbert <[email protected]>

katelynsills self-assigned this Oct 22, 2020

katelynsills force-pushed the loan branch 2 times, most recently from 0356d20 to e3714bd Compare October 27, 2020 02:56

katelynsills requested review from Chris-Hibbert and erights October 27, 2020 02:57

Chris-Hibbert reviewed Oct 28, 2020

View reviewed changes

katelynsills added the Zoe package: Zoe label Oct 28, 2020

rowgraus added this to the Chainlink Hackathon milestone Oct 28, 2020

Chris-Hibbert reviewed Oct 28, 2020

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packages/zoe/test/unitTests/contracts/loan/test-loan-e2e.js Show resolved Hide resolved

katelynsills mentioned this pull request Oct 29, 2020

Add interest calculations to loan contract and tests #1942

Closed

katelynsills force-pushed the loan branch 2 times, most recently from a46d996 to 58b7412 Compare November 3, 2020 23:57

katelynsills force-pushed the loan branch 3 times, most recently from 006a370 to 60ebe8a Compare November 5, 2020 05:39

katelynsills marked this pull request as ready for review November 5, 2020 05:44

katelynsills requested a review from Chris-Hibbert November 5, 2020 05:44

Chris-Hibbert reviewed Nov 5, 2020

View reviewed changes

katelynsills force-pushed the loan branch from e6e3632 to 97260a3 Compare November 5, 2020 23:47

katelynsills requested a review from Chris-Hibbert November 6, 2020 02:24

Chris-Hibbert approved these changes Nov 6, 2020

View reviewed changes

katelynsills and others added 5 commits November 5, 2020 21:02

feat: add basic loan contract and tests

9dfe1b6

chore: fix typo

39a5c94

Co-authored-by: Chris Hibbert <[email protected]>

fix: fix egregious import error, remove mention of tokens

2365d32

Chore: update comment

acfa268

Co-authored-by: Chris Hibbert <[email protected]>

chore: update comment

279266e

Co-authored-by: Chris Hibbert <[email protected]>

katelynsills added 7 commits November 5, 2020 21:02

chore: address PR comments

698c1ab

chore: address PR comments

a0047ee

chore: test performing liquidation from borrow invitation.

d044ff7

fix: schedule a liquidation every time the debt is updated

9a9d60d

chore: add test for malformed autoswap

d96748e

chore: capture info on the priceQuote

679d788

chore: drop console.log

8e83acd

katelynsills force-pushed the loan branch from bf20431 to 8e83acd Compare November 6, 2020 05:02

katelynsills merged commit c646bb6 into master Nov 6, 2020

katelynsills deleted the loan branch November 6, 2020 05:14

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Loan Contract #1903

Loan Contract #1903

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		import { trade } from '../../../../src/contractSupport';

		test('test doLiquidation with mocked autoswap', async t => {

Loan Contract #1903

Loan Contract #1903

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