allowing empty equilibriumDR

Author: aalavandhan

spot-vaults/contracts/DRBalancerVault.sol

@@ -102,6 +102,7 @@ contract DRBalancerVault is
 
     /// @notice The range of deviation ratios which define the equilibrium zone.
     /// @dev When the system's dr is within the equilibrium zone, no value is transferred during rebalance.
+    ///      A zero-size range is allowed and represents a single target value.
     Range public equilibriumDR;
 
     /// @notice The lag factor for underlying->perp swaps (when DR is high).
@@ -234,12 +235,13 @@ contract DRBalancerVault is
         Range memory equilibriumDR_
     ) external onlyOwner {
         if (
-            equilibriumDR_.lower >= equilibriumDR_.upper ||
-            targetDR_ <= equilibriumDR_.lower ||
-            targetDR_ >= equilibriumDR_.upper
+            equilibriumDR_.lower > equilibriumDR_.upper ||
+            targetDR_ < equilibriumDR_.lower ||
+            targetDR_ > equilibriumDR_.upper
         ) {
             revert InvalidRange();
         }
+
         targetDR = targetDR_;
         equilibriumDR = equilibriumDR_;
     }

spot-vaults/test/DRBalancerVault.ts

@@ -129,12 +129,25 @@ describe("DRBalancerVault", function () {
       });
     });
 
-    describe("when target equals a boundary", function () {
-      it("should revert", async function () {
+    describe("when target equals a boundary with non-zero range", function () {
+      it("should allow update", async function () {
         const { vault } = await loadFixture(setupContracts);
-        await expect(
-          vault.updateTargetAndEquilibriumDR(DR_ONE, [DR_ONE, drFP("1.1")]),
-        ).to.be.revertedWithCustomError(vault, "InvalidRange");
+        await vault.updateTargetAndEquilibriumDR(DR_ONE, [DR_ONE, drFP("1.1")]);
+        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(drFP("1.1"));
+      });
+    });
+
+    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);
       });
     });