diff --git a/src/utils/DIDResolved.ts b/src/utils/DIDResolved.ts
index cc6164b..859ddac 100644
--- a/src/utils/DIDResolved.ts
+++ b/src/utils/DIDResolved.ts
@@ -35,14 +35,14 @@ export default class DIDResolved {
 
     public isURL(): boolean {
         const item = this.getLastItem()
-        return item && item.valueType == "URL"
+        return item && item.valueType === "URL"
     }
-    
+
     public isDDO(): boolean {
         const item = this.getLastItem()
-        return item && item.valueType == "DDO"
+        return item && item.valueType === "DDO"
     }
-    
+
     public getValue(): string {
         const item = this.getLastItem()
         let result: string = null
diff --git a/test/keeper/DIDResolver.test.ts b/test/keeper/DIDResolver.test.ts
index 3fe2a4b..5013b30 100644
--- a/test/keeper/DIDResolver.test.ts
+++ b/test/keeper/DIDResolver.test.ts
@@ -43,11 +43,11 @@ describe("DIDResolver", () => {
 
             const didResolver = new DIDResolver(didRegistry)
             assert(didResolver)
-            
+
             const didResolved = await didResolver.resolve(did)
             assert(didResolved)
             assert(didResolved.isURL())
-            assert(didResolved.getValue() == testURL)
+            assert(didResolved.getValue() === testURL)
 
         })
         it("should register chain of attributes and resolve", async () => {
@@ -58,30 +58,30 @@ describe("DIDResolver", () => {
             const providerKey = Web3Provider.getWeb3().utils.fromAscii("provider")
 
             for ( let index = 0; index < chainLength; index ++ ) {
-                let did = DIDTools.idToDID(IdGenerator.generateId())
+                const did = DIDTools.idToDID(IdGenerator.generateId())
                 didList.push(did)
             }
-            
+
             for ( let index = 0; index < chainLength - 1; index ++ ) {
-                let didId = DIDTools.didToId(didList[index])
-                let nextDIDId = DIDTools.didToId(didList[index + 1])
-                let receipt = await didRegistry.registerAttribute(didId, ValueType.DID, providerKey,
+                const didId = DIDTools.didToId(didList[index])
+                const nextDIDId = DIDTools.didToId(didList[index + 1])
+                const receipt = await didRegistry.registerAttribute(didId, ValueType.DID, providerKey,
                     nextDIDId, ownerAccount.getId())
                 assert(receipt)
             }
-            const didId = DIDTools.didToId(didList[didList.length - 1])
-            const receipt = await didRegistry.registerAttribute(didId, ValueType.URL, providerKey,
+            const didIdLast = DIDTools.didToId(didList[didList.length - 1])
+            const receiptLast = await didRegistry.registerAttribute(didIdLast, ValueType.URL, providerKey,
                 testURL, ownerAccount.getId())
-            assert(receipt)
-        
+            assert(receiptLast)
+
             const didResolver = new DIDResolver(didRegistry)
             assert(didResolver)
-            
+
             // resolve from the first DID in the chain
             const didResolved = await didResolver.resolve(didList[0])
             assert(didResolved)
             assert(didResolved.isURL())
-            assert(didResolved.getValue() == testURL)
+            assert(didResolved.getValue() === testURL)
 
         })