added more tests and isDispensable method

src/pools/dispenser/Dispenser.ts

@@ -2,8 +2,10 @@ import Web3 from 'web3'
 import { AbiItem } from 'web3-utils'
 import { Contract } from 'web3-eth-contract'
 import { TransactionReceipt } from 'web3-eth'
+import Decimal from 'decimal.js'
 import defaultDispenserABI from '@oceanprotocol/contracts/pools/dispenser/Dispenser.json'
 import { LoggerInstance as logger, getFairGasPrice } from '../../utils/'
+import { Datatoken } from '.../../../src/datatokens/'
 
 export interface DispenserToken {
   active: boolean
@@ -119,7 +121,7 @@ export class Dispenser {
     maxBalance: string,
     allowedSwapper: string
   ): Promise<TransactionReceipt> {
-    const estGas = await this.estGasCreateDispenser(
+    const estGas = await this.estGasCreate(
       dtAddress,
       address,
       maxTokens,
@@ -409,4 +411,33 @@ export class Dispenser {
     }
     return null
   }
+
+  /**
+   * Check if tokens can be dispensed
+   * @param {String} dtAddress
+   * @param {String} address User address that will receive datatokens
+   * @param {String} amount amount of datatokens required.
+   * @return {Promise<Boolean>}
+   */
+  public async isDispensable(
+    dtAddress: string,
+    dataToken: Datatoken,
+    address: string,
+    amount: string = '1'
+  ): Promise<Boolean> {
+    const status = await this.status(dtAddress)
+    if (!status) return false
+    // check active
+    if (status.active === false) return false
+    // check maxBalance
+    const userBalance = new Decimal(await dataToken.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
+  }
 }

test/unit/pools/Dispenser.test.ts

@@ -126,4 +126,30 @@ describe('Dispenser flow', () => {
     const status = await DispenserClass.status(dtAddress)
     assert(status.active === false, 'Dispenser is still active')
   })
+
+  it('user2 sets user3 as an AllowedSwapper for the dispenser', async () => {
+    const tx = await DispenserClass.setAllowedSwapper(dtAddress, user2, user3)
+    assert(tx, 'Cannot deactivate dispenser')
+    const status = await DispenserClass.status(dtAddress)
+    assert(status.allowedSwapper === user3, 'Dispenser is still active')
+  })
+
+  it('User3 requests datatokens', async () => {
+    const check = await DispenserClass.isDispensable(dtAddress, datatoken, user3, '1')
+    assert(check === true, 'isDispensable should return true')
+    const tx = await DispenserClass.dispense(dtAddress, user3, '1', user3)
+    assert(tx, 'user3 failed to get 1DT')
+  })
+
+  it('tries to withdraw all datatokens', async () => {
+    const tx = await DispenserClass.ownerWithdraw(dtAddress, user3)
+    assert(tx === null, 'Request should fail')
+  })
+
+  it('user2 withdraws all datatokens', async () => {
+    const tx = await DispenserClass.ownerWithdraw(dtAddress, user2)
+    assert(tx, 'user2 failed to withdraw all her tokens')
+    const status = await DispenserClass.status(dtAddress)
+    assert(status.balance === '0', 'Balance > 0')
+  })
 })