Feature/dispenser (#790)

* add dispenser support

* bump contracts to 0.6.2

package-lock.json

@@ -2198,9 +2198,9 @@
       }
     },
     "@oceanprotocol/contracts": {
-      "version": "0.5.16",
-      "resolved": "https://registry.npmjs.org/@oceanprotocol/contracts/-/contracts-0.5.16.tgz",
-      "integrity": "sha512-p7aFIUT8RVoMzdPP7ML8G08BnQ09syywKjOT16hqJm0GmofunEuVffUXbryG4EkQ+qRbf/zeoxSmesi79kQXlA=="
+      "version": "0.6.2",
+      "resolved": "https://registry.npmjs.org/@oceanprotocol/contracts/-/contracts-0.6.2.tgz",
+      "integrity": "sha512-J6amHsmVbdc2rAwbUYOaY7inLV13GxPIiqbsLF78nmdIvhhGDhT2LYMyfQtxkMwQzYDP6EzD4albCgOXlWM15g=="
     },
     "@octokit/auth-token": {
       "version": "2.4.5",

package.json

@@ -46,7 +46,7 @@
   },
   "dependencies": {
     "@ethereum-navigator/navigator": "^0.5.2",
-    "@oceanprotocol/contracts": "0.5.16",
+    "@oceanprotocol/contracts": "^0.6.2",
     "@types/crypto-js": "^4.0.1",
     "cross-fetch": "^3.1.2",
     "crypto-js": "^4.0.0",

src/datatokens/Datatokens.ts

@@ -521,7 +521,7 @@ export class DataTokens {
     dataTokenAddress: string,
     newMinterAddress: string,
     address: string
-  ): Promise<string> {
+  ): Promise<TransactionReceipt> {
     const datatoken = new this.web3.eth.Contract(this.datatokensABI, dataTokenAddress, {
       from: address
     })
@@ -542,6 +542,7 @@ export class DataTokens {
       })
       return trxReceipt
     } catch (e) {
+      this.logger.error('ERROR: Propose minter failed')
       return null
     }
   }
@@ -552,7 +553,10 @@ export class DataTokens {
    * @param {String} address - only proposad minter can call this
    * @return {Promise<string>} transactionId
    */
-  public async approveMinter(dataTokenAddress: string, address: string): Promise<string> {
+  public async approveMinter(
+    dataTokenAddress: string,
+    address: string
+  ): Promise<TransactionReceipt> {
     const datatoken = new this.web3.eth.Contract(this.datatokensABI, dataTokenAddress, {
       from: address
     })

src/dispenser/Dispenser.ts

@@ -0,0 +1,350 @@
+import defaultDispenserABI from '@oceanprotocol/contracts/artifacts/Dispenser.json'
+import { TransactionReceipt } from 'web3-core'
+import { Contract } from 'web3-eth-contract'
+import { AbiItem } from 'web3-utils/types'
+import Web3 from 'web3'
+import { SubscribablePromise, Logger, getFairGasPrice } from '../utils'
+import { DataTokens } from '../datatokens/Datatokens'
+import Decimal from 'decimal.js'
+
+export interface DispenserToken {
+  active: boolean
+  owner: string
+  minterApproved: boolean
+  isTrueMinter: boolean
+  maxTokens: string
+  maxBalance: string
+  balance: string
+}
+
+export enum DispenserMakeMinterProgressStep {
+  // eslint-disable-next-line no-unused-vars
+  MakeDispenserMinter,
+  // eslint-disable-next-line no-unused-vars
+  AcceptingNewMinter
+}
+
+export enum DispenserCancelMinterProgressStep {
+  // eslint-disable-next-line no-unused-vars
+  MakeOwnerMinter,
+  // eslint-disable-next-line no-unused-vars
+  AcceptingNewMinter
+}
+
+export class OceanDispenser {
+  public GASLIMIT_DEFAULT = 1000000
+  /** Ocean related functions */
+  public dispenserAddress: string
+  public dispenserABI: AbiItem | AbiItem[]
+  public web3: Web3
+  public contract: Contract = null
+  private logger: Logger
+  public datatokens: DataTokens
+  public startBlock: number
+
+  /**
+   * Instantiate Dispenser
+   * @param {any} web3
+   * @param {String} dispenserAddress
+   * @param {any} dispenserABI
+   */
+  constructor(
+    web3: Web3,
+    logger: Logger,
+    dispenserAddress: string = null,
+    dispenserABI: AbiItem | AbiItem[] = null,
+    datatokens: DataTokens,
+    startBlock?: number
+  ) {
+    this.web3 = web3
+    this.dispenserAddress = dispenserAddress
+    if (startBlock) this.startBlock = startBlock
+    else this.startBlock = 0
+    this.dispenserABI = dispenserABI || (defaultDispenserABI.abi as AbiItem[])
+    this.datatokens = datatokens
+    if (web3)
+      this.contract = new this.web3.eth.Contract(this.dispenserABI, this.dispenserAddress)
+    this.logger = logger
+  }
+
+  /**
+   * Get dispenser status for a datatoken
+   * @param {String} dataTokenAddress
+   * @return {Promise<FixedPricedExchange>} Exchange details
+   */
+  public async status(dataTokenAddress: string): Promise<DispenserToken> {
+    try {
+      const result: DispenserToken = await this.contract.methods
+        .status(dataTokenAddress)
+        .call()
+      result.maxTokens = this.web3.utils.fromWei(result.maxTokens)
+      result.maxBalance = this.web3.utils.fromWei(result.maxBalance)
+      result.balance = this.web3.utils.fromWei(result.balance)
+      return result
+    } catch (e) {
+      this.logger.warn(`No dispenser available for data token: ${dataTokenAddress}`)
+    }
+    return null
+  }
+
+  /**
+   * Activates a new dispener.
+   * @param {String} dataToken
+   * @param {Number} maxTokens max amount of tokens to dispense
+   * @param {Number} maxBalance max balance of user. If user balance is >, then dispense will be rejected
+   * @param {String} address User address (must be owner of the dataToken)
+   * @return {Promise<TransactionReceipt>} TransactionReceipt
+   */
+  public async activate(
+    dataToken: string,
+    maxTokens: string,
+    maxBalance: string,
+    address: string
+  ): Promise<TransactionReceipt> {
+    let estGas
+    const gasLimitDefault = this.GASLIMIT_DEFAULT
+    try {
+      estGas = await this.contract.methods
+        .activate(
+          dataToken,
+          this.web3.utils.toWei(maxTokens),
+          this.web3.utils.toWei(maxBalance)
+        )
+        .estimateGas({ from: address }, (err, estGas) => (err ? gasLimitDefault : estGas))
+    } catch (e) {
+      estGas = gasLimitDefault
+    }
+    let trxReceipt = null
+    try {
+      trxReceipt = await this.contract.methods
+        .activate(
+          dataToken,
+          this.web3.utils.toWei(maxTokens),
+          this.web3.utils.toWei(maxBalance)
+        )
+        .send({
+          from: address,
+          gas: estGas + 1,
+          gasPrice: await getFairGasPrice(this.web3)
+        })
+    } catch (e) {
+      this.logger.error(`ERROR: Failed to activate dispenser: ${e.message}`)
+    }
+    return trxReceipt
+  }
+
+  /**
+   * Deactivates a dispener.
+   * @param {String} dataToken
+   * @param {String} address User address (must be owner of the dispenser)
+   * @return {Promise<TransactionReceipt>} TransactionReceipt
+   */
+  public async deactivate(
+    dataToken: string,
+    address: string
+  ): Promise<TransactionReceipt> {
+    let estGas
+    const gasLimitDefault = this.GASLIMIT_DEFAULT
+    try {
+      estGas = await this.contract.methods
+        .deactivate(dataToken)
+        .estimateGas({ from: address }, (err, estGas) => (err ? gasLimitDefault : estGas))
+    } catch (e) {
+      estGas = gasLimitDefault
+    }
+    let trxReceipt = null
+    try {
+      trxReceipt = await this.contract.methods.deactivate(dataToken).send({
+        from: address,
+        gas: estGas + 1,
+        gasPrice: await getFairGasPrice(this.web3)
+      })
+    } catch (e) {
+      this.logger.error(`ERROR: Failed to deactivate dispenser: ${e.message}`)
+    }
+    return trxReceipt
+  }
+
+  /**
+   * Make the dispenser minter of the datatoken
+   * @param {String} dataToken
+   * @param {String} address User address (must be owner of the datatoken)
+   * @return {Promise<TransactionReceipt>} TransactionReceipt
+   */
+  public makeMinter(
+    dataToken: string,
+    address: string
+  ): SubscribablePromise<DispenserMakeMinterProgressStep, TransactionReceipt> {
+    return new SubscribablePromise(async (observer) => {
+      observer.next(DispenserMakeMinterProgressStep.MakeDispenserMinter)
+      let estGas
+      const gasLimitDefault = this.GASLIMIT_DEFAULT
+      const minterTx = await this.datatokens.proposeMinter(
+        dataToken,
+        this.dispenserAddress,
+        address
+      )
+      if (!minterTx) {
+        return null
+      }
+      observer.next(DispenserMakeMinterProgressStep.AcceptingNewMinter)
+      try {
+        estGas = await this.contract.methods
+          .acceptMinter(dataToken)
+          .estimateGas({ from: address }, (err, estGas) =>
+            err ? gasLimitDefault : estGas
+          )
+      } catch (e) {
+        estGas = gasLimitDefault
+      }
+      let trxReceipt = null
+      try {
+        trxReceipt = await this.contract.methods.acceptMinter(dataToken).send({
+          from: address,
+          gas: estGas + 1,
+          gasPrice: await getFairGasPrice(this.web3)
+        })
+      } catch (e) {
+        this.logger.error(`ERROR: Failed to accept minter role: ${e.message}`)
+      }
+      return trxReceipt
+    })
+  }
+
+  /**
+   * Cancel minter role of dispenser and make the owner minter of the datatoken
+   * @param {String} dataToken
+   * @param {String} address User address (must be owner of the dispenser)
+   * @return {Promise<TransactionReceipt>} TransactionReceipt
+   */
+  public cancelMinter(
+    dataToken: string,
+    address: string
+  ): SubscribablePromise<DispenserCancelMinterProgressStep, TransactionReceipt> {
+    return new SubscribablePromise(async (observer) => {
+      observer.next(DispenserCancelMinterProgressStep.MakeOwnerMinter)
+      let estGas
+      const gasLimitDefault = this.GASLIMIT_DEFAULT
+      try {
+        estGas = await this.contract.methods
+          .removeMinter(dataToken)
+          .estimateGas({ from: address }, (err, estGas) =>
+            err ? gasLimitDefault : estGas
+          )
+      } catch (e) {
+        estGas = gasLimitDefault
+      }
+      let trxReceipt = null
+      try {
+        trxReceipt = await this.contract.methods.removeMinter(dataToken).send({
+          from: address,
+          gas: estGas + 1,
+          gasPrice: await getFairGasPrice(this.web3)
+        })
+      } catch (e) {
+        this.logger.error(`ERROR: Failed to remove minter role: ${e.message}`)
+      }
+      if (!trxReceipt) {
+        return null
+      }
+      observer.next(DispenserCancelMinterProgressStep.AcceptingNewMinter)
+      const minterTx = await this.datatokens.approveMinter(dataToken, address)
+      return minterTx
+    })
+  }
+
+  /**
+   * Request tokens from dispenser
+   * @param {String} dataToken
+   * @param {String} amount
+   * @param {String} address User address
+   * @return {Promise<TransactionReceipt>} TransactionReceipt
+   */
+  public async dispense(
+    dataToken: string,
+    address: string,
+    amount: string = '1'
+  ): Promise<TransactionReceipt> {
+    let estGas
+    const gasLimitDefault = this.GASLIMIT_DEFAULT
+    try {
+      estGas = await this.contract.methods
+        .dispense(dataToken, this.web3.utils.toWei(amount))
+        .estimateGas({ from: address }, (err, estGas) => (err ? gasLimitDefault : estGas))
+    } catch (e) {
+      estGas = gasLimitDefault
+    }
+    let trxReceipt = null
+    try {
+      trxReceipt = await this.contract.methods
+        .dispense(dataToken, this.web3.utils.toWei(amount))
+        .send({
+          from: address,
+          gas: estGas + 1,
+          gasPrice: await getFairGasPrice(this.web3)
+        })
+    } catch (e) {
+      this.logger.error(`ERROR: Failed to dispense tokens: ${e.message}`)
+    }
+    return trxReceipt
+  }
+
+  /**
+   * Withdraw all tokens from the dispenser (if any)
+   * @param {String} dataToken
+   * @param {String} address User address (must be owner of the dispenser)
+   * @return {Promise<TransactionReceipt>} TransactionReceipt
+   */
+  public async ownerWithdraw(
+    dataToken: string,
+    address: string
+  ): Promise<TransactionReceipt> {
+    let estGas
+    const gasLimitDefault = this.GASLIMIT_DEFAULT
+    try {
+      estGas = await this.contract.methods
+        .ownerWithdraw(dataToken)
+        .estimateGas({ from: address }, (err, estGas) => (err ? gasLimitDefault : estGas))
+    } catch (e) {
+      estGas = gasLimitDefault
+    }
+    let trxReceipt = null
+    try {
+      trxReceipt = await this.contract.methods.ownerWithdraw(dataToken).send({
+        from: address,
+        gas: estGas + 1,
+        gasPrice: await getFairGasPrice(this.web3)
+      })
+    } catch (e) {
+      this.logger.error(`ERROR: Failed to withdraw tokens: ${e.message}`)
+    }
+    return trxReceipt
+  }
+
+  /**
+   * Check if tokens can be dispensed
+   * @param {String} dataToken
+   * @param {String} address User address that will receive datatokens
+   * @return {Promise<Boolean>}
+   */
+  public async isDispensable(
+    dataToken: string,
+    address: string,
+    amount: string = '1'
+  ): Promise<Boolean> {
+    const status = await this.status(dataToken)
+    if (!status) return false
+    // check active
+    if (status.active === false) return false
+    // check maxBalance
+    const userBalance = new Decimal(await this.datatokens.balance(dataToken, address))
+    if (userBalance.greaterThanOrEqualTo(status.maxBalance)) return false
+    // check maxAmount
+    if (new Decimal(String(amount)).greaterThan(status.maxTokens)) return false
+    // check dispenser balance
+    const contractBalance = new Decimal(status.balance)
+    if (contractBalance.greaterThanOrEqualTo(amount) || status.isTrueMinter === true)
+      return true
+    return false
+  }
+}

src/models/Config.ts

@@ -85,6 +85,19 @@ export class Config {
    * @type {any}
    */
   public fixedRateExchangeAddressABI?: AbiItem | AbiItem[]
+
+  /**
+   * DispenserAddress
+   * @type {string}
+   */
+  public dispenserAddress?: string
+
+  /**
+   * DispenserABI
+   * @type {any}
+   */
+  public dispenserABI?: AbiItem | AbiItem[]
+
   /**
    * DDOContractAddress
    * @type {string}

src/ocean/Ocean.ts

@@ -15,6 +15,7 @@ import {
 import { Compute } from './Compute'
 import { OceanPool } from '../balancer/OceanPool'
 import { OceanFixedRateExchange } from '../exchange/FixedRateExchange'
+import { OceanDispenser } from '../dispenser/Dispenser'
 
 /**
  * Main interface for Ocean Protocol.
@@ -72,6 +73,15 @@ export class Ocean extends Instantiable {
       instance.datatokens,
       instanceConfig.config.startBlock
     )
+    instance.OceanDispenser = new OceanDispenser(
+      instanceConfig.config.web3Provider,
+      instanceConfig.logger,
+      instanceConfig.config.dispenserAddress,
+      instanceConfig.config.dispenserABI,
+      instance.datatokens,
+      instanceConfig.config.startBlock
+    )
+
     instance.onChainMetadata = new OnChainMetadata(
       instanceConfig.config.web3Provider,
       instanceConfig.logger,
@@ -155,6 +165,12 @@ export class Ocean extends Instantiable {
    */
   public fixedRateExchange: OceanFixedRateExchange
 
+  /**
+   * Ocean Dispenser submodule
+   * @type {OceanDispenser}
+   */
+  public OceanDispenser: OceanDispenser
+
   /**
      * Ocean tokens submodule
      * @type {OceanTokens}

src/utils/ConfigHelper.ts

@@ -35,6 +35,7 @@ const configs: ConfigHelperConfig[] = [
     factoryAddress: '0x1234',
     poolFactoryAddress: null,
     fixedRateExchangeAddress: null,
+    dispenserAddress: null,
     metadataContractAddress: null,
     startBlock: 0
   },
@@ -52,6 +53,7 @@ const configs: ConfigHelperConfig[] = [
     factoryAddress: null,
     poolFactoryAddress: null,
     fixedRateExchangeAddress: null,
+    dispenserAddress: null,
     metadataContractAddress: null,
     startBlock: 0
   },
@@ -68,6 +70,7 @@ const configs: ConfigHelperConfig[] = [
     factoryAddress: null,
     poolFactoryAddress: null,
     fixedRateExchangeAddress: null,
+    dispenserAddress: null,
     metadataContractAddress: null,
     startBlock: 9227563
   },
@@ -84,6 +87,7 @@ const configs: ConfigHelperConfig[] = [
     factoryAddress: null,
     poolFactoryAddress: null,
     fixedRateExchangeAddress: null,
+    dispenserAddress: null,
     metadataContractAddress: null,
     startBlock: 7294090
   },
@@ -100,6 +104,7 @@ const configs: ConfigHelperConfig[] = [
     factoryAddress: null,
     poolFactoryAddress: null,
     fixedRateExchangeAddress: null,
+    dispenserAddress: null,
     metadataContractAddress: null,
     startBlock: 11105459
   },
@@ -116,6 +121,7 @@ const configs: ConfigHelperConfig[] = [
     factoryAddress: null,
     poolFactoryAddress: null,
     fixedRateExchangeAddress: null,
+    dispenserAddress: null,
     metadataContractAddress: null,
     startBlock: 11005222
   },
@@ -132,6 +138,7 @@ const configs: ConfigHelperConfig[] = [
     factoryAddress: null,
     poolFactoryAddress: null,
     fixedRateExchangeAddress: null,
+    dispenserAddress: null,
     metadataContractAddress: null,
     startBlock: 90707
   }
@@ -147,6 +154,7 @@ export class ConfigHelper {
         DTFactory,
         BFactory,
         FixedRateExchange,
+        Dispenser,
         Metadata,
         Ocean
       } = DefaultContractsAddresses[network]
@@ -154,6 +162,7 @@ export class ConfigHelper {
         factoryAddress: DTFactory,
         poolFactoryAddress: BFactory,
         fixedRateExchangeAddress: FixedRateExchange,
+        dispenserAddress: Dispenser,
         metadataContractAddress: Metadata,
         oceanTokenAddress: Ocean,
         ...(process.env.AQUARIUS_URI && { metadataCacheUri: process.env.AQUARIUS_URI })
@@ -169,11 +178,19 @@ export class ConfigHelper {
             'utf8'
           )
         )
-        const { DTFactory, BFactory, FixedRateExchange, Metadata, Ocean } = data[network]
+        const {
+          DTFactory,
+          BFactory,
+          FixedRateExchange,
+          Dispenser,
+          Metadata,
+          Ocean
+        } = data[network]
         configAddresses = {
           factoryAddress: DTFactory,
           poolFactoryAddress: BFactory,
           fixedRateExchangeAddress: FixedRateExchange,
+          dispenserAddress: Dispenser,
           metadataContractAddress: Metadata,
           oceanTokenAddress: Ocean,
           ...(process.env.AQUARIUS_URI && { metadataCacheUri: process.env.AQUARIUS_URI })

test/DispenserContractHandler.ts

@@ -0,0 +1,50 @@
+import Web3 from 'web3'
+import { Contract } from 'web3-eth-contract'
+import { AbiItem } from 'web3-utils/types'
+
+export class DispenserContractHandler {
+  public contract: Contract
+  public accounts: string[]
+  public contractBytecode: string
+  public contractAddress: string
+  public web3: Web3
+
+  constructor(contractABI: AbiItem[], contractBytecode: string, web3: Web3) {
+    this.web3 = web3
+    this.contract = new this.web3.eth.Contract(contractABI)
+    this.contractBytecode = contractBytecode
+  }
+
+  public async getAccounts(): Promise<string[]> {
+    this.accounts = await this.web3.eth.getAccounts()
+    return this.accounts
+  }
+
+  public async deployContracts() {
+    await this.getAccounts()
+    // get est gascost
+    const estGas = await this.contract
+      .deploy({
+        data: this.contractBytecode,
+        arguments: []
+      })
+      .estimateGas(function (err, estGas) {
+        if (err) console.log('DeployContracts: ' + err)
+        return estGas
+      })
+    // deploy the contract and get it's address
+    this.contractAddress = await this.contract
+      .deploy({
+        data: this.contractBytecode,
+        arguments: []
+      })
+      .send({
+        from: this.accounts[0],
+        gas: estGas + 1,
+        gasPrice: '3000000000'
+      })
+      .then(function (contract) {
+        return contract.options.address
+      })
+  }
+}

test/unit/dispenser/Dispenser.test.ts

@@ -0,0 +1,239 @@
+import { assert } from 'chai'
+import { AbiItem } from 'web3-utils/types'
+import { TestContractHandler } from '../../TestContractHandler'
+import { DispenserContractHandler } from '../../DispenserContractHandler'
+import { DataTokens } from '../../../src/datatokens/Datatokens'
+import { LoggerInstance } from '../../../src/utils'
+import Web3 from 'web3'
+import factory from '@oceanprotocol/contracts/artifacts/DTFactory.json'
+import datatokensTemplate from '@oceanprotocol/contracts/artifacts/DataTokenTemplate.json'
+import { OceanDispenser } from '../../../src/dispenser/Dispenser'
+
+import DispenserContract = require('@oceanprotocol/contracts/artifacts/Dispenser.json')
+const web3 = new Web3('http://127.0.0.1:8545')
+
+describe('Dispenser flow', () => {
+  let DispenserAddress: string
+  let DispenserClass
+  let bob: string
+  let alice: string
+  let charlie: string
+  let datatoken: DataTokens
+  let tokenAddress: string
+  let tokenAddress2: string
+  let tokenAddress3: string
+
+  let owner: string
+  let contracts: TestContractHandler
+
+  const consoleDebug = false
+  const tokenAmount = '1000'
+  const blob = 'http://localhost:8030/api/v1/services/consume'
+
+  before(async () => {
+    // deploy SFactory
+    const Contracts = new DispenserContractHandler(
+      DispenserContract.abi as AbiItem[],
+      DispenserContract.bytecode,
+      web3
+    )
+    await Contracts.getAccounts()
+    owner = Contracts.accounts[0]
+
+    await Contracts.deployContracts()
+    DispenserAddress = Contracts.contractAddress
+    assert(DispenserAddress !== null)
+
+    // deploy DT Factory
+    contracts = new TestContractHandler(
+      factory.abi as AbiItem[],
+      datatokensTemplate.abi as AbiItem[],
+      datatokensTemplate.bytecode,
+      factory.bytecode,
+      web3
+    )
+    await contracts.getAccounts()
+    owner = contracts.accounts[0]
+    alice = contracts.accounts[1]
+    bob = contracts.accounts[2]
+    charlie = contracts.accounts[3]
+    await contracts.deployContracts(owner)
+
+    // initialize DataTokens
+    datatoken = new DataTokens(
+      contracts.factoryAddress,
+      factory.abi as AbiItem[],
+      datatokensTemplate.abi as AbiItem[],
+      web3,
+      LoggerInstance
+    )
+    assert(datatoken !== null)
+  })
+
+  it('should create some datatoken2', async () => {
+    tokenAddress = await datatoken.create(
+      blob,
+      alice,
+      '1000000000000000',
+      'AliceDT',
+      'DTA'
+    )
+    assert(tokenAddress !== null)
+    if (consoleDebug) console.log("Alice's address:" + alice)
+    if (consoleDebug) console.log('data Token address:' + tokenAddress)
+    tokenAddress2 = await datatoken.create(
+      blob,
+      alice,
+      '1000000000000000',
+      'AliceDT2',
+      'DTA2'
+    )
+    assert(tokenAddress2 !== null)
+    tokenAddress3 = await datatoken.create(
+      blob,
+      alice,
+      '1000000000000000',
+      'AliceDT3',
+      'DTA3'
+    )
+    assert(tokenAddress3 !== null)
+  })
+
+  it('should initialize Dispenser class', async () => {
+    DispenserClass = new OceanDispenser(
+      web3,
+      LoggerInstance,
+      DispenserAddress,
+      DispenserContract.abi as AbiItem[],
+      datatoken
+    )
+    assert(DispenserClass !== null)
+  })
+
+  it('Alice mints 1000 tokens', async () => {
+    const txid = await datatoken.mint(tokenAddress, alice, tokenAmount)
+    if (consoleDebug) console.log(txid)
+    assert(txid !== null)
+  })
+
+  it('Alice creates a dispenser', async () => {
+    const tx = await DispenserClass.activate(tokenAddress, '1', '1', alice)
+    assert(tx, 'Cannot activate dispenser')
+  })
+
+  it('Alice should make the dispenser a minter', async () => {
+    const tx = await DispenserClass.makeMinter(tokenAddress, alice)
+    assert(tx, 'Cannot make dispenser a minter')
+  })
+
+  it('Alice gets the dispenser status', async () => {
+    const status = await DispenserClass.status(tokenAddress)
+    assert(status.active === true, 'Dispenser not active')
+    assert(status.owner === alice, 'Dispenser owner is not alice')
+    assert(status.minterApproved === true, 'Dispenser is not a minter')
+  })
+
+  it('Alice should fail to get the dispenser status for an unknown token', async () => {
+    const status = await DispenserClass.status(tokenAddress3)
+    assert(
+      status.owner === '0x0000000000000000000000000000000000000000',
+      'Owner of inexistent dispenser should be 0'
+    )
+  })
+
+  it('Alice should fail to get the dispenser status for zero address', async () => {
+    const status = await DispenserClass.status(0x0000000000000000000000000000000000000000)
+    assert(status === null)
+  })
+
+  it('Bob requests more datatokens then allowed', async () => {
+    const check = await DispenserClass.isDispensable(tokenAddress, bob, '10')
+    assert(check === false, 'isDispensable should return false')
+    const tx = await DispenserClass.dispense(tokenAddress, bob, '10')
+    assert(tx === null, 'Request should fail')
+  })
+
+  it('Bob requests datatokens', async () => {
+    const check = await DispenserClass.isDispensable(tokenAddress, bob, '1')
+    assert(check === true, 'isDispensable should return true')
+    const tx = await DispenserClass.dispense(tokenAddress, bob, '1')
+    assert(tx, 'Bob failed to get 1DT')
+  })
+
+  it('Bob requests more datatokens but he exceeds maxBalance', async () => {
+    const check = await DispenserClass.isDispensable(tokenAddress, bob, '10')
+    assert(check === false, 'isDispensable should return false')
+    const tx = await DispenserClass.dispense(tokenAddress, bob, '10')
+    assert(tx === null, 'Request should fail')
+  })
+
+  it('Alice deactivates the dispenser', async () => {
+    const tx = await DispenserClass.deactivate(tokenAddress, alice)
+    assert(tx, 'Cannot deactivate dispenser')
+    const status = await DispenserClass.status(tokenAddress)
+    assert(status.active === false, 'Dispenser is still active')
+  })
+
+  it('Charlie should fail to get datatokens', async () => {
+    const check = await DispenserClass.isDispensable(tokenAddress, charlie, '1')
+    assert(check === false, 'isDispensable should return false')
+    const tx = await DispenserClass.dispense(tokenAddress, charlie, '1')
+    assert(tx === null, 'Charlie should fail to get 1DT')
+  })
+
+  it('Alice calls removeMinter role and checks if she is the new minter', async () => {
+    const tx = await DispenserClass.cancelMinter(tokenAddress, alice)
+    assert(tx, 'Cannot cancel minter role')
+    const status = await DispenserClass.status(tokenAddress)
+    assert(status.minterApproved === false, 'Dispenser is still a minter')
+    assert(status.owner === alice, 'Dispenser is not owned by Alice')
+    const isMinter = await datatoken.isMinter(tokenAddress, alice)
+    assert(isMinter === true, 'ALice is not the minter')
+  })
+
+  it('Bob should fail to activate a dispenser for a token for he is not a minter', async () => {
+    const tx = await DispenserClass.activate(tokenAddress, '1', '1', bob)
+    assert(tx === null, 'Bob should fail to activate dispenser')
+  })
+
+  it('Alice creates a dispenser without minter role', async () => {
+    const tx = await DispenserClass.activate(tokenAddress2, '1', '1', alice)
+    assert(tx, 'Cannot activate dispenser')
+  })
+  it('Bob requests datatokens but there are none', async () => {
+    const check = await DispenserClass.isDispensable(tokenAddress2, bob, '1')
+    assert(check === false, 'isDispensable should return false')
+    const tx = await DispenserClass.dispense(tokenAddress2, bob, '1')
+    assert(tx === null, 'Request should fail')
+  })
+  it('Alice mints tokens and transfer them to the dispenser.', async () => {
+    const mintTx = await datatoken.mint(
+      tokenAddress2,
+      alice,
+      '10',
+      DispenserClass.dispenserAddress
+    )
+    assert(mintTx, 'Alice cannot mint tokens')
+    const status = await DispenserClass.status(tokenAddress2)
+    assert(status.balance > 0, 'Balances do not match')
+  })
+
+  it('Bob requests datatokens', async () => {
+    const check = await DispenserClass.isDispensable(tokenAddress2, bob, '1')
+    assert(check === true, 'isDispensable should return true')
+    const tx = await DispenserClass.dispense(tokenAddress2, bob, '1')
+    assert(tx, 'Bob failed to get 1DT')
+  })
+
+  it('Bob tries to withdraw all datatokens', async () => {
+    const tx = await DispenserClass.ownerWithdraw(tokenAddress2, bob)
+    assert(tx === null, 'Request should fail')
+  })
+
+  it('Alice withdraws all datatokens', async () => {
+    const tx = await DispenserClass.ownerWithdraw(tokenAddress2, alice)
+    assert(tx, 'Alice failed to withdraw all her tokens')
+    const status = await DispenserClass.status(tokenAddress2)
+    assert(status.balance === '0', 'Balance > 0')
+  })
+})