1 files changed, 20 insertions, 0 deletions
diff --git a/packages/contracts/src/utils/assertions.ts b/packages/contracts/src/utils/assertions.ts
new file mode 100644
index 000000000..72c2734d8
--- /dev/null
+++ b/packages/contracts/src/utils/assertions.ts
@@ -0,0 +1,20 @@
+import * as chai from 'chai';
+import * as _ from 'lodash';
+
+import { constants } from './constants';
+
+const expect = chai.expect;
+
+// throws if the given promise does not reject with one of two expected error
+// messages.
+export const expectRevertOrAlwaysFailingTransaction = <T>(p: Promise<T>) => {
+    return expect(p)
+        .to.be.rejected()
+        .then(e => {
+            expect(e).to.satisfy(
+                (err: Error) =>
+                    _.includes(err.message, constants.REVERT) ||
+                    _.includes(err.message, constants.ALWAYS_FAILING_TRANSACTION),
+            );
+        });
+};