diff --git a/src/datatokens/Datatokens.ts b/src/datatokens/Datatokens.ts
index 22f7fb00..cde50a1c 100644
--- a/src/datatokens/Datatokens.ts
+++ b/src/datatokens/Datatokens.ts
@@ -119,14 +119,14 @@ export class DataTokens {
    * @param {String} toAddress
    * @param {string} amount Number of datatokens, as number. Will be converted to wei
    * @param {String} address
-   * @return {Promise<string>} transactionId
+   * @return {Promise<TransactionReceipt>} transactionId
    */
   public async approve(
     dataTokenAddress: string,
     spender: string,
     amount: string,
     address: string
-  ): Promise<string> {
+  ): Promise<TransactionReceipt> {
     const datatoken = new this.web3.eth.Contract(this.datatokensABI, dataTokenAddress, {
       from: address
     })
@@ -142,14 +142,14 @@ export class DataTokens {
    * @param {String} address
    * @param {String} amount Number of datatokens, as number. Will be converted to wei
    * @param {String} toAddress   - only if toAddress is different from the minter
-   * @return {Promise<string>} transactionId
+   * @return {Promise<TransactionReceipt>} transactionId
    */
   public async mint(
     dataTokenAddress: string,
     address: string,
     amount: string,
     toAddress?: string
-  ): Promise<string> {
+  ): Promise<TransactionReceipt> {
     const destAddress = toAddress || address
     const datatoken = new this.web3.eth.Contract(this.datatokensABI, dataTokenAddress, {
       from: address
@@ -178,14 +178,14 @@ export class DataTokens {
    * @param {String} toAddress
    * @param {String} amount Number of datatokens, as number. Will be converted to wei
    * @param {String} address
-   * @return {Promise<string>} transactionId
+   * @return {Promise<TransactionReceipt>} transactionId
    */
   public async transfer(
     dataTokenAddress: string,
     toAddress: string,
     amount: string,
     address: string
-  ): Promise<string> {
+  ): Promise<TransactionReceipt> {
     return this.transferToken(dataTokenAddress, toAddress, amount, address)
   }
 
@@ -195,14 +195,14 @@ export class DataTokens {
    * @param {String} toAddress
    * @param {String} amount Number of datatokens, as number. Will be converted to wei
    * @param {String} address
-   * @return {Promise<string>} transactionId
+   * @return {Promise<TransactionReceipt>} transactionId
    */
   public async transferToken(
     dataTokenAddress: string,
     toAddress: string,
     amount: string,
     address: string
-  ): Promise<string> {
+  ): Promise<TransactionReceipt> {
     const weiAmount = this.web3.utils.toWei(amount)
     return this.transferWei(dataTokenAddress, toAddress, weiAmount, address)
   }
@@ -213,14 +213,14 @@ export class DataTokens {
    * @param {String} toAddress
    * @param {String} amount Number of datatokens, as number. Expressed as wei
    * @param {String} address
-   * @return {Promise<string>} transactionId
+   * @return {Promise<TransactionReceipt>} transactionId
    */
   public async transferWei(
     dataTokenAddress: string,
     toAddress: string,
     amount: string,
     address: string
-  ): Promise<string> {
+  ): Promise<TransactionReceipt> {
     const datatoken = new this.web3.eth.Contract(this.datatokensABI, dataTokenAddress, {
       from: address
     })
diff --git a/test/integration/ComputeFlow.test.ts b/test/integration/ComputeFlow.test.ts
index 7eb17b78..58e890bf 100644
--- a/test/integration/ComputeFlow.test.ts
+++ b/test/integration/ComputeFlow.test.ts
@@ -5,7 +5,7 @@ import { Ocean } from '../../src/ocean/Ocean'
 import { ConfigHelper } from '../../src/utils/ConfigHelper'
 
 import { assert } from 'chai'
-import { ServiceComputePrivacy } from '../../src/ddo/interfaces/Service'
+import { ServiceCommon, ServiceComputePrivacy } from '../../src/ddo/interfaces/Service'
 import Web3 from 'web3'
 import factory from '@oceanprotocol/contracts/artifacts/DTFactory.json'
 import datatokensTemplate from '@oceanprotocol/contracts/artifacts/DataTokenTemplate.json'
@@ -27,14 +27,14 @@ describe('Compute flow', () => {
   let datasetWithTrustedAlgo
   let algorithmAsset
   let contracts
-  let datatoken
+  let datatoken: DataTokens
   let tokenAddress
   let tokenAddressNoRawAlgo
   let tokenAddressWithTrustedAlgo
   let tokenAddressAlgorithm
-  let price
+  let price: string
   let ocean
-  let computeService
+  let computeService: ServiceCommon
   let data
   let blob
   let jobId
@@ -77,7 +77,7 @@ describe('Compute flow', () => {
     owner = (await ocean.accounts.list())[0]
     alice = (await ocean.accounts.list())[1]
     bob = (await ocean.accounts.list())[2]
-    data = { t: 1, url: ocean.config.metadataStoreUri }
+    data = { t: 1, url: config.metadataStoreUri }
     blob = JSON.stringify(data)
     await contracts.deployContracts(owner.getId())
   })
diff --git a/test/integration/Marketplaceflow.test.ts b/test/integration/Marketplaceflow.test.ts
index b827bad0..d84ee4b0 100644
--- a/test/integration/Marketplaceflow.test.ts
+++ b/test/integration/Marketplaceflow.test.ts
@@ -9,10 +9,10 @@ import { ConfigHelper } from '../../src/utils/ConfigHelper'
 import Web3 from 'web3'
 import factory from '@oceanprotocol/contracts/artifacts/DTFactory.json'
 import datatokensTemplate from '@oceanprotocol/contracts/artifacts/DataTokenTemplate.json'
-import { EditableMetadata } from '../../src/lib'
+import { Account, EditableMetadata, ServiceAccess, ServiceCommon } from '../../src/lib'
 const web3 = new Web3('http://127.0.0.1:8545')
 
-function sleep(ms) {
+function sleep(ms: number) {
   return new Promise((resolve) => {
     setTimeout(resolve, ms)
   })
@@ -21,19 +21,19 @@ function sleep(ms) {
 use(spies)
 
 describe('Marketplace flow', () => {
-  let owner
-  let bob
+  let owner: Account
+  let bob: Account
   let ddo
-  let alice
+  let alice: Account
   let asset
-  let marketplace
-  let contracts
-  let datatoken
-  let tokenAddress
-  let service1
-  let price
-  let ocean
-  let accessService
+  let marketplace: Account
+  let contracts: TestContractHandler
+  let datatoken: DataTokens
+  let tokenAddress: string
+  let service1: ServiceAccess
+  let price: string
+  let ocean: Ocean
+  let accessService: ServiceCommon
   let data
   let blob
 
@@ -55,7 +55,7 @@ describe('Marketplace flow', () => {
     alice = (await ocean.accounts.list())[1]
     bob = (await ocean.accounts.list())[2]
     marketplace = (await ocean.accounts.list())[3]
-    data = { t: 1, url: ocean.config.metadataStoreUri }
+    data = { t: 1, url: config.metadataStoreUri }
     blob = JSON.stringify(data)
     await contracts.deployContracts(owner.getId())
   })
@@ -156,8 +156,8 @@ describe('Marketplace flow', () => {
 
   it('Marketplace posts asset for sale', async () => {
     accessService = await ocean.assets.getServiceByType(ddo.id, 'access')
-    price = 20
-    assert.equal(accessService.attributes.main.cost * price, 200)
+    price = '20'
+    assert.equal(accessService.attributes.main.cost * Number(price), 200)
   })
 
   it('Bob gets datatokens', async () => {
@@ -199,9 +199,9 @@ describe('Marketplace flow', () => {
     assert(balanceBefore === balanceAfter)
   })
 
-  it('owner can list there assets', async () => {
+  it('owner can list their assets', async () => {
     const assets = await ocean.assets.ownerAssets(alice.getId())
-    assert(assets.length > 0)
+    assert(assets.results.length > 0)
   })
 
   it('Alice updates metadata', async () => {
diff --git a/test/integration/Provider.test.ts b/test/integration/Provider.test.ts
index e3ddcb24..8a6ceb3c 100644
--- a/test/integration/Provider.test.ts
+++ b/test/integration/Provider.test.ts
@@ -3,16 +3,17 @@ import config from './config'
 import { assert } from 'console'
 
 describe('Provider tests', () => {
-  let ocean
+  let ocean: Ocean
+
   it('Initialize Ocean', async () => {
     ocean = await Ocean.getInstance(config)
   })
   it('Alice tests invalid provider', async () => {
-    const valid = ocean.provider.isValidProvider('http://example.net')
+    const valid = await ocean.provider.isValidProvider('http://example.net')
     assert(valid === false)
   })
   it('Alice tests valid provider', async () => {
-    const valid = ocean.provider.isValidProvider('http://127.0.0.1:8030')
+    const valid = await ocean.provider.isValidProvider('http://127.0.0.1:8030')
     assert(valid === true)
   })
 })
diff --git a/test/integration/Simpleflow.test.ts b/test/integration/Simpleflow.test.ts
index 26409b98..6ec1389e 100644
--- a/test/integration/Simpleflow.test.ts
+++ b/test/integration/Simpleflow.test.ts
@@ -8,13 +8,14 @@ import datatokensTemplate from '@oceanprotocol/contracts/artifacts/DataTokenTemp
 const web3 = new Web3('http://127.0.0.1:8545')
 
 describe('Simple flow', () => {
-  let owner
-  let bob
-  let alice
-  let contracts
-  let datatoken
-  let tokenAddress
-  let transactionId
+  let owner: string
+  let bob: string
+  let alice: string
+  let contracts: TestContractHandler
+  let datatoken: DataTokens
+  let tokenAddress: string
+  let transactionId: string
+
   const tokenAmount = '100'
   const transferAmount = '1'
   const blob = 'http://localhost:8030/api/v1/services/consume'