Merge pull request #130 from ampleforth/naguib-0-rebase

If oracle data is invalid apply 0 supply change instead of reverting transaction.

Author: ahnaguib

contracts/UFragmentsPolicy.sol

@@ -91,28 +91,29 @@ contract UFragmentsPolicy is Ownable {
         uint256 cpi;
         bool cpiValid;
         (cpi, cpiValid) = cpiOracle.getData();
-        require(cpiValid);
 
         uint256 targetRate = cpi.mul(10 ** DECIMALS).div(baseCpi);
 
         uint256 exchangeRate;
         bool rateValid;
         (exchangeRate, rateValid) = marketOracle.getData();
-        require(rateValid);
 
         if (exchangeRate > MAX_RATE) {
             exchangeRate = MAX_RATE;
         }
 
-        int256 supplyDelta = computeSupplyDelta(exchangeRate, targetRate);
+        int256 supplyDelta = 0;
 
-        // Apply the Dampening factor.
-        supplyDelta = supplyDelta.div(rebaseLag.toInt256Safe());
+        if (cpiValid && rateValid) {
+            supplyDelta = computeSupplyDelta(exchangeRate, targetRate);
 
-        if (supplyDelta > 0 && uFrags.totalSupply().add(uint256(supplyDelta)) > MAX_SUPPLY) {
-            supplyDelta = (MAX_SUPPLY.sub(uFrags.totalSupply())).toInt256Safe();
-        }
+            // Apply the Dampening factor.
+            supplyDelta = supplyDelta.div(rebaseLag.toInt256Safe());
 
+            if (supplyDelta > 0 && uFrags.totalSupply().add(uint256(supplyDelta)) > MAX_SUPPLY) {
+                supplyDelta = (MAX_SUPPLY.sub(uFrags.totalSupply())).toInt256Safe();
+            }
+        }
         uint256 supplyAfterRebase = uFrags.rebase(epoch, supplyDelta);
         assert(supplyAfterRebase <= MAX_SUPPLY);
         emit LogRebase(epoch, exchangeRate, cpi, supplyDelta, lastRebaseTimestampSec);

test/unit/UFragmentsPolicy.js

@@ -363,20 +363,11 @@ contract('UFragmentsPolicy:Rebase', async function (accounts) {
   before('setup UFragmentsPolicy contract', setupContracts);
 
   describe('when the market oracle returns invalid data', function () {
-    it('should fail', async function () {
+    it('supply delta should equal zero', async function () {
       await mockExternalData(INITIAL_RATE_30P_MORE, INITIAL_CPI, 1000, false);
-      expect(
-        await chain.isEthException(uFragmentsPolicy.rebase())
-      ).to.be.true;
-    });
-  });
+      r = await uFragmentsPolicy.rebase();
+      r.logs[0].args.requestedSupplyAdjustment.should.be.bignumber.eq(0);
 
-  describe('when the market oracle returns valid data', function () {
-    it('should NOT fail', async function () {
-      await mockExternalData(INITIAL_RATE_30P_MORE, INITIAL_CPI, 1000, true);
-      expect(
-        await chain.isEthException(uFragmentsPolicy.rebase())
-      ).to.be.false;
     });
   });
 });
@@ -387,20 +378,11 @@ contract('UFragmentsPolicy:Rebase', async function (accounts) {
   describe('when the cpi oracle returns invalid data', function () {
     it('should fail', async function () {
       await mockExternalData(INITIAL_RATE_30P_MORE, INITIAL_CPI, 1000, true, false);
-      expect(
-        await chain.isEthException(uFragmentsPolicy.rebase())
-      ).to.be.true;
+      r = await uFragmentsPolicy.rebase();
+      r.logs[0].args.requestedSupplyAdjustment.should.be.bignumber.eq(0)
     });
   });
 
-  describe('when the cpi oracle returns valid data', function () {
-    it('should NOT fail', async function () {
-      await mockExternalData(INITIAL_RATE_30P_MORE, INITIAL_CPI, 1000, true, true);
-      expect(
-        await chain.isEthException(uFragmentsPolicy.rebase())
-      ).to.be.false;
-    });
-  });
 });
 
 contract('UFragmentsPolicy:Rebase', async function (accounts) {