Quoting Charlie,
DataAttribute is a class that was somewhat important in earlier versions of NUnit. Currently, it's a holdover and is not used in the code at all. We left it in the code to avoid needlessly breaking anything.
This seems like a good thing to document in the source. Can we document this using an obsoletion warning so that people who use it become aware?
[Obsolete("Holdover from NUnit v2. Please inherit from Attribute or PropertyAttribute and " +
"implement IParameterDataSource.", error: false)]
Quoting Charlie,
This seems like a good thing to document in the source. Can we document this using an obsoletion warning so that people who use it become aware?