Add ReentrancyGuard

test/helpers/ReentrancyAttack.sol

@@ -0,0 +1,11 @@
+pragma solidity ^0.4.8;
+
+contract ReentrancyAttack {
+
+  function callSender(bytes4 data) {
+    if(!msg.sender.call(data)) {
+      throw;
+    }
+  }
+
+}

test/helpers/ReentrancyMock.sol

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+pragma solidity ^0.4.8;
+
+import '../../contracts/ReentrancyGuard.sol';
+import './ReentrancyAttack.sol';
+
+contract ReentrancyMock is ReentrancyGuard {
+
+  uint256 public counter;
+
+  function ReentrancyMock() {
+    counter = 0;
+  }
+
+  function count() private {
+    counter += 1;
+  }
+
+  function countLocalRecursive(uint n) public nonReentrant {
+    if(n > 0) {
+      count();
+      countLocalRecursive(n - 1);
+    }
+  }
+
+  function countThisRecursive(uint256 n) public nonReentrant {
+    bytes4 func = bytes4(keccak256("countThisRecursive(uint256)"));
+    if(n > 0) {
+      count();
+      bool result = this.call(func, n - 1);
+      if(result != true) {
+        throw;
+      }
+    }
+  }
+
+  function countAndCall(ReentrancyAttack attacker) public nonReentrant {
+    count();
+    bytes4 func = bytes4(keccak256("callback()"));
+    attacker.callSender(func);
+  }
+
+  function callback() external nonReentrant {
+    count();
+  }
+
+}

test/helpers/expectThrow.js

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+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');
+};