Add validateOrderFillableThrowIfNotFillableAsync to public methods in order to validate orders in an orderbook without a specific taker in mind

src/contract_wrappers/exchange_wrapper.ts

@@ -28,6 +28,7 @@ import {
     LogCancelContractEventArgs,
     LogWithDecodedArgs,
     MethodOpts,
+    ValidateOrderFillableOpts,
 } from '../types';
 import {assert} from '../utils/assert';
 import {utils} from '../utils/utils';
@@ -623,6 +624,24 @@ export class ExchangeWrapper extends ContractWrapper {
         const exchangeAddress = exchangeInstance.address;
         return exchangeAddress;
     }
+    /**
+     * Checks if order is still fillable and throws an error otherwise.
+     * @param   signedOrder     An object that conforms to the SignedOrder interface. The
+     *                          signedOrder you wish to validate.
+     * @param   opts            An object that conforms to the ValidateOrderFillableOpts
+     *                          interface. Allows specifying a specific fillTakerTokenAmount
+     *                          to validate for.
+     */
+    public async validateOrderFillableThrowIfNotFillableAsync(
+        signedOrder: SignedOrder, opts: ValidateOrderFillableOpts,
+    ): Promise<void> {
+        assert.doesConformToSchema('signedOrder', signedOrder, schemas.signedOrderSchema);
+        const zrxTokenAddress = await this._getZRXTokenAddressAsync();
+        const expectedFillTakerTokenAmount = !_.isUndefined(opts) ? opts.expectedFillTakerTokenAmount : undefined;
+        await this._orderValidationUtils.validateOrderFillableThrowIfNotFillableAsync(
+            signedOrder, zrxTokenAddress, expectedFillTakerTokenAmount,
+        );
+    }
     /**
      * Checks if order fill will succeed and throws an error otherwise.
      * @param   signedOrder             An object that conforms to the SignedOrder interface. The

src/types.ts

@@ -433,6 +433,16 @@ export interface Artifact {
     }};
 }
 
+/*
+ * expectedFillTakerTokenAmount: If specified, the validation method will ensure that the
+ * supplied order's maker has a sufficient allowance/balance to fill this amount of the order's
+ * takerTokenAmount. If not specified, the validation method ensures that the maker has a sufficient
+ * allowance/balance to fill the entire remaining order.
+ */
+export interface ValidateOrderFillableOpts {
+    expectedFillTakerTokenAmount?: BigNumber.BigNumber;
+}
+
 /*
  * defaultBlock: The block up to which to query the blockchain state. Setting this to a historical block number
  * let's the user query the blockchain's state at an arbitrary point in time. In order for this to work, the

src/utils/order_validation_utils.ts

@@ -1,3 +1,4 @@
+import * as _ from 'lodash';
 import {ExchangeContractErrs, SignedOrder, Order, ZeroExError} from '../types';
 import {ZeroEx} from '../0x';
 import {TokenWrapper} from '../contract_wrappers/token_wrapper';
@@ -12,6 +13,26 @@ export class OrderValidationUtils {
         this.tokenWrapper = tokenWrapper;
         this.exchangeWrapper = exchangeWrapper;
     }
+    public async validateOrderFillableThrowIfNotFillableAsync(
+        signedOrder: SignedOrder, zrxTokenAddress: string, expectedFillTakerTokenAmount?: BigNumber.BigNumber,
+    ): Promise<void> {
+        const orderHash = utils.getOrderHashHex(signedOrder);
+        const unavailableTakerTokenAmount = await this.exchangeWrapper.getUnavailableTakerAmountAsync(orderHash);
+        if (signedOrder.makerTokenAmount.eq(unavailableTakerTokenAmount)) {
+            throw new Error(ExchangeContractErrs.OrderRemainingFillAmountZero);
+        }
+        const currentUnixTimestampSec = utils.getCurrentUnixTimestamp();
+        if (signedOrder.expirationUnixTimestampSec.lessThan(currentUnixTimestampSec)) {
+            throw new Error(ExchangeContractErrs.OrderFillExpired);
+        }
+        let fillTakerTokenAmount = signedOrder.takerTokenAmount.minus(unavailableTakerTokenAmount);
+        if (!_.isUndefined(expectedFillTakerTokenAmount)) {
+            fillTakerTokenAmount = expectedFillTakerTokenAmount;
+        }
+        await this.validateFillOrderMakerBalancesAllowancesThrowIfInvalidAsync(
+            signedOrder, fillTakerTokenAmount, zrxTokenAddress,
+        );
+    }
     public async validateFillOrderThrowIfInvalidAsync(signedOrder: SignedOrder,
                                                       fillTakerTokenAmount: BigNumber.BigNumber,
                                                       takerAddress: string,