I have now just committed YAML data sets to the Database Extension for PHPUnit. So now all those that love the simplicity and straightforwardness of YAML can use it with your data sets. I have also created a persistor for YAML datasets so you can easily convert existing data sets or database data into YAML representations.
He includes an example of a bit of YAML markup and one of the major hurdles he had to overcome - trailing line breaks (as shown in the table_2/column 8 in the example). This functionality also includes a persistor that lets you convert things back the other day - current data set to YAML markup. You can find out more about data sets in PHPUnit in this section of the project's manual.