contribution contracts tests

apps/contribution/contracts/Contribution.sol

@@ -152,6 +152,8 @@ contract Contribution is AragonApp {
 
   function add(uint32 amount, uint32 contributorId, bytes32 hashDigest, uint8 hashFunction, uint8 hashSize) public isInitialized auth(ADD_CONTRIBUTION_ROLE) {
     //require(canPerform(msg.sender, ADD_CONTRIBUTION_ROLE, new uint32[](0)), 'nope');
+    require(amount > 0, "INVALID_AMOUNT");
+
     uint32 contributionId = contributionsCount + 1;
     ContributionData storage c = contributions[contributionId];
     c.exists = true;

apps/contribution/contracts/test/Spoof.sol

@@ -0,0 +1,18 @@
+pragma solidity ^0.4.24;
+
+import "@aragon/os/contracts/acl/ACL.sol";
+import "@aragon/os/contracts/kernel/Kernel.sol";
+import "@aragon/os/contracts/factory/DAOFactory.sol";
+import "../../../contributor/contracts/Contributor.sol";
+import "../../../token/contracts/Token.sol";
+
+// You might think this file is a bit odd, but let me explain.
+// We only use for now those imported contracts in our tests, which
+// means Truffle will not compile them for us, because they are from
+// an external dependency.
+
+
+// solium-disable-next-line no-empty-blocks
+contract Spoof {
+  // ...
+}