Working Features can be measured through automated tests.
A Working Feature is complete if the set of tests that "verify" it are passing.
The tests are tagged as verifying that feature, and likely include integration, performance and UI tests as well as unit.
Honestly it does not matter if the tests are written before or after the code. (Its really hard to write tests for a UI element that does not exist yet.)
How can I tell if people are working on the feature I want them to?
Working Features are all that matters.
Working Features can be measured through automated tests.
A Working Feature is complete if the set of tests that "verify" it are passing.
The tests are tagged as verifying that feature, and likely include integration, performance and UI tests as well as unit.
Honestly it does not matter if the tests are written before or after the code. (Its really hard to write tests for a UI element that does not exist yet.)
How can I tell if people are working on the feature I want them to?
You can read the code. But otherwise you cant.