From 0270777cfc1979e2b802c21fca7d7333e1d2e34d Mon Sep 17 00:00:00 2001
From: Lawrence Forman <me@merklejerk.com>
Date: Thu, 19 Sep 2019 05:41:00 -0400
Subject: [PATCH] `@0x/contracts-test-utils`: Add `hexHash()` to `hex_utils`.

---
 contracts/test-utils/CHANGELOG.json   |  4 ++++
 contracts/test-utils/src/hex_utils.ts |  7 +++++++
 contracts/test-utils/src/index.ts     | 11 ++++++++++-
 3 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/contracts/test-utils/CHANGELOG.json b/contracts/test-utils/CHANGELOG.json
index 875f1fbc30..8496757a6f 100644
--- a/contracts/test-utils/CHANGELOG.json
+++ b/contracts/test-utils/CHANGELOG.json
@@ -86,6 +86,10 @@
                 "note": "Tweaks/Upgrades to `hex_utils`, most notably `hexSlice()`",
                 "pr": 2155
             },
+            {
+                "note": "Add `hexHash()` to `hex_utils`",
+                "pr": 2155
+            },
             {
                 "note": "Add `shortZip()` to `lang_utils.ts`",
                 "pr": 2155
diff --git a/contracts/test-utils/src/hex_utils.ts b/contracts/test-utils/src/hex_utils.ts
index 05b7a9c781..007bbf9bd5 100644
--- a/contracts/test-utils/src/hex_utils.ts
+++ b/contracts/test-utils/src/hex_utils.ts
@@ -58,6 +58,13 @@ export function hexSlice(n: Numberish, start: number, end?: number): string {
     return '0x'.concat(hex.substring(sliceStart, sliceEnd));
 }
 
+/**
+ * Get the keccak hash of some data.
+ */
+export function hexHash(n: Numberish): string {
+    return ethUtil.bufferToHex(ethUtil.sha3(ethUtil.toBuffer(toHex(n))));
+ }
+
 /**
  * Convert a string, a number, or a BigNumber into a hex string.
  * Works with negative numbers, as well.
diff --git a/contracts/test-utils/src/index.ts b/contracts/test-utils/src/index.ts
index 7df55bf89a..bdac824e23 100644
--- a/contracts/test-utils/src/index.ts
+++ b/contracts/test-utils/src/index.ts
@@ -28,7 +28,16 @@ export { bytes32Values, testCombinatoriallyWithReferenceFunc, uint256Values } fr
 export { TransactionFactory } from './transaction_factory';
 export { MutatorContractFunction, TransactionHelper } from './transaction_helper';
 export { testWithReferenceFuncAsync } from './test_with_reference';
-export { hexConcat, hexLeftPad, hexInvert, hexSlice, hexRandom, hexRightPad, toHex } from './hex_utils';
+export {
+    hexConcat,
+    hexHash,
+    hexLeftPad,
+    hexInvert,
+    hexSlice,
+    hexRandom,
+    hexRightPad,
+    toHex,
+} from './hex_utils';
 export {
     BatchMatchOrder,
     ContractName,