Add ReentrancyGuard

test/helpers/expectThrow.js

@@ -0,0 +1,20 @@
+export default async promise => {
+  try {
+    await promise;
+  } catch (error) {
+    // TODO: Check jump destination to destinguish between a throw
+    //       and an actual invalid jump.
+    const invalidJump = error.message.search('invalid JUMP') >= 0;
+    // TODO: When we contract A calls contract B, and B throws, instead
+    //       of an 'invalid jump', we get an 'out of gas' error. How do
+    //       we distinguish this from an actual out of gas event? (The
+    //       testrpc log actually show an 'invalid jump' event.)
+    const outOfGas = error.message.search('out of gas') >= 0;
+    assert(
+      invalidJump || outOfGas,
+      "Expected throw, got '" + error + "' instead",
+    );
+    return;
+  }
+  assert.fail('Expected throw not received');
+};