I have implemented the code pretty much as written, but am having trouble getting the test condition registered.
Your article does not describe how to add the assembly to the GAC, or to generate the public key that you have in the xml, but I found this info in Sachin's original article. It would be helpful to see this info in your article, as well as a suggestion for how to name your project at the start.
I do think that you mistyped the line
<extension type="TablesEqual.TablesEqual" enabled="true" />
in your xml file: Assuming that you named your assembly TablesEqual, shouldn't you use TablesEqual.DataEqual?
There is also a disagreement between your article and Sachin's about where to put the xml file. He says the DBPro directory, you say the MSVSTEDB - ENU directory.
On to my problem - I have the code compiled into a DLL. I have run gacutil and have copied the public key into the xml file. I've put the xml file in both directories suggested above, and still have no luck in getting the condition to show up in my tests. I've tried creating new test projects and also tried manually adding my dll as a reference for the test project. None of this seems to work.