diff --git a/.eslintrc b/.eslintrc
index f092bb1c..e049094f 100644
--- a/.eslintrc
+++ b/.eslintrc
@@ -8,6 +8,7 @@
     "plugin:@typescript-eslint/recommended"
   ],
   "rules": {
-    "prefer-rest-params": "off" // super(...arguments)
+    "prefer-rest-params": "off", // super(...arguments)
+    "@typescript-eslint/no-inferrable-types": "off"
   }
 }
diff --git a/tests/crossChainSwap.test.ts b/tests/crossChainSwap.test.ts
index a7b814da..afbe4194 100644
--- a/tests/crossChainSwap.test.ts
+++ b/tests/crossChainSwap.test.ts
@@ -81,7 +81,7 @@ describe('Test SmartContract `CrossChainSwap`', () => {
                     pubKeyOrAddrToSign: bobPubKey,
                 } as MethodCallOptions<CrossChainSwap>
             )
-        expect(callContract()).to.be.rejectedWith(
+        return expect(callContract()).to.be.rejectedWith(
             /locktime has not yet expired/
         )
     })
diff --git a/tests/crowdfund.test.ts b/tests/crowdfund.test.ts
index 3097675c..c46285f1 100644
--- a/tests/crowdfund.test.ts
+++ b/tests/crowdfund.test.ts
@@ -68,6 +68,6 @@ describe('Test SmartContract `Crowdfund`', () => {
                 } as MethodCallOptions<Crowdfund>
             )
 
-        expect(callContract()).to.be.rejectedWith(/fundraising expired/)
+        return expect(callContract()).to.be.rejectedWith(/fundraising expired/)
     })
 })
diff --git a/tests/demo.test.ts b/tests/demo.test.ts
index d596f835..e48bc9da 100644
--- a/tests/demo.test.ts
+++ b/tests/demo.test.ts
@@ -31,12 +31,12 @@ describe('Test SmartContract `Demo`', () => {
     it('should throw when calling `add`', async () => {
         await demo.deploy(1)
         const callContract = async () => await demo.methods.add(-5n)
-        expect(callContract()).to.be.rejectedWith(/add check failed/)
+        return expect(callContract()).to.be.rejectedWith(/add check failed/)
     })
 
     it('should throw when calling `sub`', async () => {
         await demo.deploy(1)
         const callContract = async () => await demo.methods.sub(9n)
-        expect(callContract()).to.be.rejectedWith(/sub check failed/)
+        return expect(callContract()).to.be.rejectedWith(/sub check failed/)
     })
 })
diff --git a/tests/erc20.test.ts b/tests/erc20.test.ts
index a5a1bbc8..2a5825e2 100644
--- a/tests/erc20.test.ts
+++ b/tests/erc20.test.ts
@@ -338,7 +338,7 @@ describe('Test SmartContract `ERC20`', () => {
                 150n
             )
 
-        expect(callContract()).to.be.rejectedWith(
+        return expect(callContract()).to.be.rejectedWith(
             /Execution failed, ERC20: insufficient allowance/
         )
     })
diff --git a/tests/erc721.test.ts b/tests/erc721.test.ts
index 26cd74c9..7fc0887d 100644
--- a/tests/erc721.test.ts
+++ b/tests/erc721.test.ts
@@ -35,7 +35,7 @@ describe('Test SmartContract `Erc721`', () => {
                 () => getDummySig() // mint without correct minter sig
             )
 
-        expect(callContract()).to.be.rejectedWith(
+        return expect(callContract()).to.be.rejectedWith(
             /minter signature check failed/
         )
     })
@@ -60,7 +60,7 @@ describe('Test SmartContract `Erc721`', () => {
                 (sigResps) => findSig(sigResps, myPublicKey) // minterSig
             )
 
-        expect(callContract()).to.be.rejectedWith(
+        return expect(callContract()).to.be.rejectedWith(
             /token was already minted before/
         )
     })
@@ -91,7 +91,7 @@ describe('Test SmartContract `Erc721`', () => {
                 } as MethodCallOptions<Erc721>
             )
 
-        expect(callContract()).to.be.rejectedWith(
+        return expect(callContract()).to.be.rejectedWith(
             /sender doesn't have the token/
         )
     })
diff --git a/tests/hashedMapNonState.test.ts b/tests/hashedMapNonState.test.ts
index 26534018..35787013 100644
--- a/tests/hashedMapNonState.test.ts
+++ b/tests/hashedMapNonState.test.ts
@@ -49,7 +49,7 @@ describe('Test SmartContract `HashedMapNonState`', () => {
         await hashedMapNonState.deploy(1)
         const callContract = async () =>
             await hashedMapNonState.methods.delete(2n)
-        expect(callContract()).to.be.rejectedWith(
+        return expect(callContract()).to.be.rejectedWith(
             /hashedMap should have the key before delete/
         )
     })
diff --git a/tests/hashedSetNonState.test.ts b/tests/hashedSetNonState.test.ts
index 86d4b7cc..1f783f6d 100644
--- a/tests/hashedSetNonState.test.ts
+++ b/tests/hashedSetNonState.test.ts
@@ -51,7 +51,7 @@ describe('Test SmartContract `HashedSetNonState`', () => {
         await hashedSetNonState.deploy(1)
         const callContract = async () =>
             await hashedSetNonState.methods.delete(2n)
-        expect(callContract()).to.be.rejectedWith(
+        return expect(callContract()).to.be.rejectedWith(
             /hashedSet should have the key before delete/
         )
     })
diff --git a/tests/helloWorld.test.ts b/tests/helloWorld.test.ts
index f08015ab..f1ea1699 100644
--- a/tests/helloWorld.test.ts
+++ b/tests/helloWorld.test.ts
@@ -26,6 +26,8 @@ describe('Test SmartContract `HelloWorld`', () => {
         await helloWorld.deploy(1)
         const callContract = async () =>
             await helloWorld.methods.unlock(toByteString('wrong message', true))
-        expect(callContract()).to.be.rejectedWith(/Not expected message!/)
+        return expect(callContract()).to.be.rejectedWith(
+            /Not expected message!/
+        )
     })
 })
diff --git a/tests/multiPartyHashPuzzle.test.ts b/tests/multiPartyHashPuzzle.test.ts
index b69093b9..d37acbe0 100644
--- a/tests/multiPartyHashPuzzle.test.ts
+++ b/tests/multiPartyHashPuzzle.test.ts
@@ -56,6 +56,6 @@ describe('Test SmartContract `MultiPartyHashPuzzle`', () => {
         preimagesWrong[0] = sha256('aabbcc')
         const callContract = async () =>
             await instance.methods.unlock(preimagesWrong)
-        expect(callContract()).to.be.rejectedWith(/hash mismatch/)
+        return expect(callContract()).to.be.rejectedWith(/hash mismatch/)
     })
 })
diff --git a/tests/multiPartyHashPuzzleOpt.test.ts b/tests/multiPartyHashPuzzleOpt.test.ts
index c44eea47..71dde000 100644
--- a/tests/multiPartyHashPuzzleOpt.test.ts
+++ b/tests/multiPartyHashPuzzleOpt.test.ts
@@ -53,6 +53,6 @@ describe('Test SmartContract `MultiPartyHashPuzzleOpt`', () => {
         preimagesWrong[0] = sha256('aabbcc')
         const callContract = async () =>
             await instance.methods.unlock(preimagesWrong)
-        expect(callContract()).to.be.rejectedWith(/hash mismatch/)
+        return expect(callContract()).to.be.rejectedWith(/hash mismatch/)
     })
 })
diff --git a/tests/multiSig.test.ts b/tests/multiSig.test.ts
index e2636741..7b37e5a1 100644
--- a/tests/multiSig.test.ts
+++ b/tests/multiSig.test.ts
@@ -81,6 +81,6 @@ describe('Test SmartContract `P2MS`', () => {
                 } as MethodCallOptions<MultiSigPayment>
             )
 
-        expect(callContract()).to.be.rejectedWith(/Execution failed/)
+        return expect(callContract()).to.be.rejectedWith(/Execution failed/)
     })
 })
diff --git a/tests/ordinalLock.test.ts b/tests/ordinalLock.test.ts
index 2c62d245..a1c66c71 100644
--- a/tests/ordinalLock.test.ts
+++ b/tests/ordinalLock.test.ts
@@ -8,6 +8,7 @@ import {
     PubKey,
     hash160,
     ByteString,
+    ContractTransaction,
 } from 'scrypt-ts'
 import { OrdinalLock, purchaseTxBuilder } from '../src/contracts/ordinalLock'
 import chaiAsPromised from 'chai-as-promised'
@@ -108,7 +109,7 @@ describe('Test SmartContract `OrdinalLock`', () => {
                 current: OrdinalLock,
                 options: MethodCallOptions<OrdinalLock>,
                 destOutput: ByteString
-            ): Promise<any> => {
+            ): Promise<ContractTransaction> => {
                 const destOutputBR = new bsv.encoding.BufferReader(
                     Buffer.from(destOutput, 'hex')
                 )
@@ -132,6 +133,7 @@ describe('Test SmartContract `OrdinalLock`', () => {
                 const result = {
                     tx: unsignedTx,
                     atInputIndex: 0, // the contract input's index
+                    nexts: [],
                 }
 
                 return Promise.resolve(result)
@@ -143,7 +145,7 @@ describe('Test SmartContract `OrdinalLock`', () => {
             await instance.methods.purchase(destOutputStr, {
                 changeAddress: await buyerSigner.getDefaultAddress(),
             } as MethodCallOptions<OrdinalLock>)
-        expect(callContract()).to.be.rejectedWith(/Execution failed/)
+        return expect(callContract()).to.be.rejectedWith(/Execution failed/)
     })
 
     it('should fail cancel method w bad sig.', async () => {
@@ -161,6 +163,6 @@ describe('Test SmartContract `OrdinalLock`', () => {
                     changeAddress: wrongKey.toAddress(),
                 } as MethodCallOptions<OrdinalLock>
             )
-        expect(callContract()).to.be.rejectedWith(/bad seller/)
+        return expect(callContract()).to.be.rejectedWith(/bad seller/)
     })
 })
diff --git a/tests/p2pkh.test.ts b/tests/p2pkh.test.ts
index f819df3b..9625f874 100644
--- a/tests/p2pkh.test.ts
+++ b/tests/p2pkh.test.ts
@@ -69,7 +69,9 @@ describe('Test SmartContract `P2PKH`', () => {
                 } as MethodCallOptions<P2PKH>
             )
 
-        expect(callContract()).to.be.rejectedWith(/signature check failed/)
+        return expect(callContract()).to.be.rejectedWith(
+            /signature check failed/
+        )
     })
 
     it('should fail if passing wrong public key', async () => {
@@ -90,7 +92,7 @@ describe('Test SmartContract `P2PKH`', () => {
                     pubKeyOrAddrToSign: myPublicKey, // use the correct private key, `myPrivateKey`, to sign
                 } as MethodCallOptions<P2PKH>
             )
-        expect(callContract()).to.be.rejectedWith(
+        return expect(callContract()).to.be.rejectedWith(
             /public key hashes are not equal/
         )
     })
diff --git a/tests/priceBet.test.ts b/tests/priceBet.test.ts
index 3ddb61c4..c4aefc6b 100644
--- a/tests/priceBet.test.ts
+++ b/tests/priceBet.test.ts
@@ -138,6 +138,8 @@ describe('Test SmartContract `PriceBet`', () => {
                 } as MethodCallOptions<PriceBet>
             )
 
-        expect(callContract()).to.be.rejectedWith(/signature check failed/)
+        return expect(callContract()).to.be.rejectedWith(
+            /signature check failed/
+        )
     })
 })
diff --git a/tests/recallable.test.ts b/tests/recallable.test.ts
index f29873ae..15b7ceeb 100644
--- a/tests/recallable.test.ts
+++ b/tests/recallable.test.ts
@@ -39,7 +39,7 @@ describe('Test SmartContract `Recallable`', () => {
                     pubKeyOrAddrToSign: alicePublicKey,
                 } as MethodCallOptions<Recallable>
             )
-        expect(callContract()).to.be.rejectedWith(
+        return expect(callContract()).to.be.rejectedWith(
             /invalid value of `satoshisSent`/
         )
     })
@@ -55,7 +55,7 @@ describe('Test SmartContract `Recallable`', () => {
                 } as MethodCallOptions<Recallable>
             )
 
-        expect(callContract()).to.be.rejectedWith(
+        return expect(callContract()).to.be.rejectedWith(
             /invalid value of `satoshisSent`/
         )
     })
@@ -67,7 +67,7 @@ describe('Test SmartContract `Recallable`', () => {
                 PubKey(toHex(bobPublicKey)),
                 BigInt(1)
             )
-        expect(callContract()).to.be.rejectedWith(
+        return expect(callContract()).to.be.rejectedWith(
             /user's signature check failed/
         )
     })
diff --git a/tests/socialRecovery.test.ts b/tests/socialRecovery.test.ts
index 16a98dd1..d0844919 100644
--- a/tests/socialRecovery.test.ts
+++ b/tests/socialRecovery.test.ts
@@ -70,7 +70,9 @@ describe('Test SmartContract `SocialRecovery`', () => {
                     pubKeyOrAddrToSign: wrongKey.toPublicKey(),
                 } as MethodCallOptions<SocialRecovery>
             )
-        expect(callContract()).to.be.rejectedWith(/signature check failed/)
+        return expect(callContract()).to.be.rejectedWith(
+            /signature check failed/
+        )
     })
 
     it('should pass updating signing key when threshold reached.', async () => {
@@ -142,7 +144,7 @@ describe('Test SmartContract `SocialRecovery`', () => {
                 } as MethodCallOptions<SocialRecovery>
             )
 
-        expect(callContract()).to.be.rejectedWith(
+        return expect(callContract()).to.be.rejectedWith(
             /Guardian threshold not reached/
         )
     })
diff --git a/tests/statefulMultiSig.test.ts b/tests/statefulMultiSig.test.ts
index 0de71436..25a067c6 100644
--- a/tests/statefulMultiSig.test.ts
+++ b/tests/statefulMultiSig.test.ts
@@ -139,7 +139,9 @@ describe('Test SmartContract `StatefulMultiSig`', () => {
                     },
                 } as MethodCallOptions<StatefulMultiSig>
             )
-        expect(callContract()).to.be.rejectedWith(/signature check failed/)
+        return expect(callContract()).to.be.rejectedWith(
+            /signature check failed/
+        )
     })
 
     it('should fail pay if threshold not reached', async () => {
@@ -157,7 +159,7 @@ describe('Test SmartContract `StatefulMultiSig`', () => {
                         await statefulMultiSig.signer.getDefaultAddress(),
                 } as MethodCallOptions<StatefulMultiSig>
             )
-        expect(callContract()).to.be.rejectedWith(
+        return expect(callContract()).to.be.rejectedWith(
             /Not enough valid signatures./
         )
     })
diff --git a/tests/timeLock.test.ts b/tests/timeLock.test.ts
index 8de00a41..bf045184 100644
--- a/tests/timeLock.test.ts
+++ b/tests/timeLock.test.ts
@@ -31,7 +31,7 @@ describe('Test SmartContract `TimeLock`', () => {
             await timeLock.methods.unlock({
                 lockTime: 1673500100,
             } as MethodCallOptions<TimeLock>)
-        expect(callContract()).to.be.rejectedWith(
+        return expect(callContract()).to.be.rejectedWith(
             /locktime has not yet expired/
         )
     })