Create tests for SafeMath

contracts/test-helpers/SafeMathMock.sol

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+pragma solidity ^0.4.4;
+import '../SafeMath.sol';
+
+contract SafeMathMock is SafeMath {
+  uint public result;
+
+  function multiply(uint a, uint b) {
+    result = safeMul(a, b);
+  }
+
+  function subtract(uint a, uint b) {
+    result = safeSub(a, b);
+  }
+
+  function add(uint a, uint b) {
+    result = safeAdd(a, b);
+  }
+}