ual(200m, source.Balance);
  Assert.AreEqual(150m, destination.Balance);
}</pre>
</div>

<p>We are testing the transactional property of our business method - all operations are successful or none. Compile and run - red bar. OK, we've made $300.00 out of a thin air (1999 .com d&eacute;j&agrave; vu?) - the source account has the correct balance of 200.00 but the destination account shows : $450.00. How do we fix this? Can we just move the minimum balance check call in front of the updates:</p>

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