[feature request] provide per-test coverage map
Main motivation for this feature is to provide the necessary data required to implement IDE feature - instant feedback to user, which line in code has failed which test(s).
Similar to Visual Studio Live Testing:

Is there a way to communicate what is the context of current code coverage execution, for example, populate lcov TN (Test Name)?
If not, can you recommend how to handle this info from the test runner: Maybe execute tests one by one and save coverage separately? But wouldn't this cause performance / coverage map merge problems?
PS istanbul does not support this feature, and seems this will not be implemented anytime soon
A feature like this this would be very useful to create reports that only show explicit coverage by tests.
Assume there are 2 modules, A and B where code in A calls B. Test exists for A and B. I would like the coverage for B to only include results from running the tests for B. The calls of code in B when testing A should be excluded.
The report then shows code actually targeted by each test, excluding side effect from other tests.