A True Metrics: Running Tested Features (RTF)

Ron Jeffries, one of the founding fathers of Agile wrote an excellent summary of what he considers a truly valuable metric, RTF or Running Tested Features. You can view the article here.

From the article:

What is the Point of the Project?

I'm just guessing, but I think the point of most software development projects is software that works, and that has the most features possible per dollar of investment. I call that notion Running Tested [Features], and in fact it can be measured, to a degree.

Imagine the following definition of RTF:

1. The desired software is broken down into named features (requirements, stories) which are part of what it means to deliver the desired system.
2. For each named feature, there are one or more automated acceptance tests which, when they work, will show that the feature in question is implemented.
3. The RTF metric shows, at every moment in the project, how many features are passing all their acceptance tests.

How many customer-defined features are known, through independently-defined testing, to be working? Now there's a metric I could live with.