1 files changed, 51 insertions, 0 deletions
diff --git a/packages/asset-buyer/src/utils/assert.ts b/packages/asset-buyer/src/utils/assert.ts
new file mode 100644
index 000000000..04f425237
--- /dev/null
+++ b/packages/asset-buyer/src/utils/assert.ts
@@ -0,0 +1,51 @@
+import { assert as sharedAssert } from '@0xproject/assert';
+import { schemas } from '@0xproject/json-schemas';
+import { SignedOrder } from '@0xproject/types';
+import * as _ from 'lodash';
+
+import { BuyQuote, OrderProvider, OrderProviderRequest } from '../types';
+
+export const assert = {
+    ...sharedAssert,
+    isValidBuyQuote(variableName: string, buyQuote: BuyQuote): void {
+        sharedAssert.isHexString(`${variableName}.assetData`, buyQuote.assetData);
+        sharedAssert.doesConformToSchema(`${variableName}.orders`, buyQuote.orders, schemas.signedOrdersSchema);
+        sharedAssert.doesConformToSchema(`${variableName}.feeOrders`, buyQuote.feeOrders, schemas.signedOrdersSchema);
+        sharedAssert.isBigNumber(`${variableName}.minRate`, buyQuote.minRate);
+        sharedAssert.isBigNumber(`${variableName}.maxRate`, buyQuote.maxRate);
+        sharedAssert.isBigNumber(`${variableName}.assetBuyAmount`, buyQuote.assetBuyAmount);
+        if (!_.isUndefined(buyQuote.feePercentage)) {
+            sharedAssert.isNumber(`${variableName}.feePercentage`, buyQuote.feePercentage);
+        }
+    },
+    isValidOrderProvider(variableName: string, orderFetcher: OrderProvider): void {
+        sharedAssert.isFunction(`${variableName}.getOrdersAsync`, orderFetcher.getOrdersAsync);
+    },
+    isValidOrderProviderRequest(variableName: string, orderFetcherRequest: OrderProviderRequest): void {
+        sharedAssert.isHexString(`${variableName}.makerAssetData`, orderFetcherRequest.makerAssetData);
+        sharedAssert.isHexString(`${variableName}.takerAssetData`, orderFetcherRequest.takerAssetData);
+        sharedAssert.isNumber(`${variableName}.networkId`, orderFetcherRequest.networkId);
+    },
+    areValidProvidedOrders(variableName: string, orders: SignedOrder[]): void {
+        if (orders.length === 0) {
+            return;
+        }
+        const makerAssetData = orders[0].makerAssetData;
+        const takerAssetData = orders[0].takerAssetData;
+        const filteredOrders = _.filter(
+            orders,
+            order => order.makerAssetData === makerAssetData && order.takerAssetData === takerAssetData,
+        );
+        sharedAssert.assert(
+            orders.length === filteredOrders.length,
+            `Expected all orders in ${variableName} to have the same makerAssetData and takerAssetData.`,
+        );
+    },
+    isValidPercentage(variableName: string, percentage: number): void {
+        assert.isNumber(variableName, percentage);
+        assert.assert(
+            percentage >= 0 && percentage <= 1,
+            `Expected ${variableName} to be between 0 and 1, but is ${percentage}`,
+        );
+    },
+};