no-op supply change when oracle inputs are invalid (#290)

Author: aalavandhan

contracts/UFragmentsPolicy.sol

@@ -125,16 +125,14 @@ contract UFragmentsPolicy is Ownable {
         epoch = epoch.add(1);
 
         (uint256 targetRate, bool targetRateValid) = getTargetRate();
-        require(targetRateValid);
-
         (uint256 exchangeRate, bool rateValid) = getExchangeRate();
-        require(rateValid);
-
         if (exchangeRate > MAX_RATE) {
             exchangeRate = MAX_RATE;
         }
 
-        int256 supplyDelta = computeSupplyDelta(exchangeRate, targetRate);
+        int256 supplyDelta = (targetRateValid && rateValid)
+            ? computeSupplyDelta(exchangeRate, targetRate)
+            : int256(0);
         if (supplyDelta > 0 && uFrags.totalSupply().add(uint256(supplyDelta)) > MAX_SUPPLY) {
             supplyDelta = (MAX_SUPPLY.sub(uFrags.totalSupply())).toInt256Safe();
         }

scripts/deploy.ts

@@ -199,7 +199,6 @@ task('deploy:wampl', 'Deploy wampl contract')
     await verify(hre, wampl.address, [args.ampl])
   })
 
-
 task('deploy:oracle', 'Deploy the median oracle contract')
   .addParam('expiry', 'The report expiry')
   .addParam('delay', 'The report delay')
@@ -213,12 +212,7 @@ task('deploy:oracle', 'Deploy the median oracle contract')
 
     // deploy contract
     const oracle = await deployContract(hre, 'MedianOracle', deployer, [])
-    await oracle.init(
-      args.expiry,
-      args.delay,
-      1,
-      args.scalar
-    )
+    await oracle.init(args.expiry, args.delay, 1, args.scalar)
     console.log('Oracle deployed to:', oracle.address)
 
     // wait and verify

test/unit/UFragmentsPolicy.ts

@@ -866,15 +866,15 @@ describe('UFragmentsPolicy:Rebase', async function () {
   })
 
   describe('when the market oracle returns invalid data', function () {
-    it('should fail', async function () {
+    it('should NOT fail', async function () {
       await mockExternalData(
         INITIAL_RATE_30P_MORE,
         INITIAL_TARGET_RATE,
         1000,
         false,
       )
       await increaseTime(60)
-      await expect(uFragmentsPolicy.connect(orchestrator).rebase()).to.be
+      await expect(uFragmentsPolicy.connect(orchestrator).rebase()).to.not.be
         .reverted
     })
   })
@@ -908,7 +908,7 @@ describe('UFragmentsPolicy:Rebase', async function () {
   })
 
   describe('when the cpi oracle returns invalid data', function () {
-    it('should fail', async function () {
+    it('should NOT fail', async function () {
       await mockExternalData(
         INITIAL_RATE_30P_MORE,
         INITIAL_TARGET_RATE,
@@ -917,7 +917,7 @@ describe('UFragmentsPolicy:Rebase', async function () {
         false,
       )
       await increaseTime(60)
-      await expect(uFragmentsPolicy.connect(orchestrator).rebase()).to.be
+      await expect(uFragmentsPolicy.connect(orchestrator).rebase()).to.not.be
         .reverted
     })
   })
@@ -1204,6 +1204,50 @@ describe('UFragmentsPolicy:Rebase', async function () {
       ).to.eq(0)
     })
   })
+
+  describe('rate is invalid', function () {
+    before(async function () {
+      await mockExternalData(
+        INITIAL_RATE_30P_MORE,
+        INITIAL_TARGET_RATE,
+        1000,
+        false,
+      )
+      await uFragmentsPolicy.connect(deployer).setDeviationThreshold(0)
+      await increaseTime(60)
+    })
+
+    it('should emit Rebase with 0 requestedSupplyAdjustment', async function () {
+      expect(
+        (
+          await parseRebaseEvent(
+            uFragmentsPolicy.connect(orchestrator).rebase(),
+          )
+        ).requestedSupplyAdjustment,
+      ).to.eq(0)
+    })
+  })
+
+  describe('target rate is invalid', function () {
+    before(async function () {
+      await mockExternalData(
+        INITIAL_RATE,
+        INITIAL_TARGET_RATE_25P_MORE,
+        1000,
+        true,
+        false,
+      )
+      await uFragmentsPolicy.connect(deployer).setDeviationThreshold(0)
+      await increaseTime(60)
+    })
+
+    it('should emit Rebase with 0 requestedSupplyAdjustment', async function () {
+      expect(
+        (await parseRebaseEvent(uFragmentsPolicy.connect(orchestrator).rebase()))
+          .requestedSupplyAdjustment,
+      ).to.eq(0)
+    })
+  })
 })
 
 describe('UFragmentsPolicy:Rebase', async function () {