Added unit tests for ReentrancyGuard

contracts/utils/test/reentrancy_guard.ts

@@ -0,0 +1,40 @@
+import { chaiSetup, provider, txDefaults, web3Wrapper } from '@0x/contracts-test-utils';
+import { BlockchainLifecycle } from '@0x/dev-utils';
+import { ReentrancyGuardRevertErrors } from '@0x/utils';
+import * as chai from 'chai';
+import * as _ from 'lodash';
+
+import { artifacts, TestReentrancyGuardContract } from '../src';
+
+chaiSetup.configure();
+const expect = chai.expect;
+const blockchainLifecycle = new BlockchainLifecycle(web3Wrapper);
+
+describe('ReentrancyGuard', () => {
+    let guard: TestReentrancyGuardContract;
+
+    before(async () => {
+        await blockchainLifecycle.startAsync();
+        // Deploy TestReentrancyGuard
+        guard = await TestReentrancyGuardContract.deployFrom0xArtifactAsync(
+            artifacts.TestReentrancyGuard,
+            provider,
+            txDefaults,
+        );
+    });
+
+    after(async () => {
+        await blockchainLifecycle.revertAsync();
+    });
+
+    describe('nonReentrant', () => {
+        it('should throw if reentrancy occurs', async () => {
+            const expectedError = new ReentrancyGuardRevertErrors.IllegalReentrancyError();
+            return expect(guard.guarded.sendTransactionAsync(true)).to.revertWith(expectedError);
+        });
+
+        it('should succeed if reentrancy does not occur', async () => {
+            expect(guard.guarded.sendTransactionAsync(false)).to.be.fulfilled; // tslint:disable-line:no-unused-expression
+        });
+    });
+});