diff --git a/test/helpers/balanceDiff.js b/test/helpers/balanceDiff.js
new file mode 100644
index 000000000..8f88ba400
--- /dev/null
+++ b/test/helpers/balanceDiff.js
@@ -0,0 +1,10 @@
+async function balanceDifference (account, promise) {
+  const balanceBefore = web3.eth.getBalance(account);
+  await promise();
+  const balanceAfter = web3.eth.getBalance(account);
+  return balanceAfter.minus(balanceBefore);
+}
+
+module.exports = {
+  balanceDifference,
+};