Swap target contract at test by using abstract interface

contracts/Bounty.sol

@@ -9,9 +9,7 @@ import './PullPayment.sol';
  */
 
 contract Target {
-  function checkInvarient() returns(bool){
-    return true;
-  }
+  function checkInvarient() returns(bool);
 }
 
 contract Bounty is PullPayment {
@@ -23,8 +21,8 @@ contract Bounty is PullPayment {
     if (claimed) throw;
   }
 
-  function createTarget() returns(Target) {
-    target = new Target();
+  function createTarget(address targetAddress) returns(Target) {
+    target = Target(targetAddress);
     researchers[target] = msg.sender;
     return target;
   }
@@ -37,7 +35,6 @@ contract Bounty is PullPayment {
     address researcher = researchers[target];
     if (researcher == 0) throw;
     // Check Target contract invariants
-    // Customize this to the specifics of your contract
     if (!target.checkInvarient()) {
       throw;
     }

contracts/test-helpers/InsecureTargetMock.sol

@@ -0,0 +1,7 @@
+pragma solidity ^0.4.0;
+
+contract InsecureTargetMock {
+  function checkInvarient() returns(bool){
+    return false;
+  }
+}

contracts/test-helpers/SecureTargetMock.sol

@@ -0,0 +1,7 @@
+pragma solidity ^0.4.0;
+
+contract SecureTargetMock {
+  function checkInvarient() returns(bool){
+    return true;
+  }
+}