allowing empty equilibriumDR

Author: aalavandhan

spot-vaults/contracts/DRBalancerVault.sol

@@ -233,13 +233,16 @@ contract DRBalancerVault is
         uint256 targetDR_,
         Range memory equilibriumDR_
     ) external onlyOwner {
-        if (
-            equilibriumDR_.lower >= equilibriumDR_.upper ||
-            targetDR_ <= equilibriumDR_.lower ||
-            targetDR_ >= equilibriumDR_.upper
-        ) {
+        bool isZeroRange = equilibriumDR_.lower == equilibriumDR_.upper;
+        bool invalidRange = ((equilibriumDR_.lower > equilibriumDR_.upper) ||
+            (isZeroRange && targetDR_ != equilibriumDR_.lower) ||
+            (!isZeroRange &&
+                (targetDR_ <= equilibriumDR_.lower ||
+                    targetDR_ >= equilibriumDR_.upper)));
+        if (invalidRange) {
             revert InvalidRange();
         }
+
         targetDR = targetDR_;
         equilibriumDR = equilibriumDR_;
     }

spot-vaults/test/DRBalancerVault.ts

@@ -129,7 +129,7 @@ describe("DRBalancerVault", function () {
       });
     });
 
-    describe("when target equals a boundary", function () {
+    describe("when target equals a boundary with non-zero range", function () {
       it("should revert", async function () {
         const { vault } = await loadFixture(setupContracts);
         await expect(
@@ -138,6 +138,17 @@ describe("DRBalancerVault", function () {
       });
     });
 
+    describe("when range size is zero at target", function () {
+      it("should allow update", async function () {
+        const { vault } = await loadFixture(setupContracts);
+        await vault.updateTargetAndEquilibriumDR(DR_ONE, [DR_ONE, DR_ONE]);
+        expect(await vault.targetDR()).to.eq(DR_ONE);
+        const r = await vault.equilibriumDR();
+        expect(r[0]).to.eq(DR_ONE);
+        expect(r[1]).to.eq(DR_ONE);
+      });
+    });
+
     describe("when valid", function () {
       it("should update target DR and equilibrium range", async function () {
         const { vault } = await loadFixture(setupContracts);