drake using testthat

[feinmann]

Are there examples how to implement tests using testthat and drake?

[wlandau]

@lbusett floated this idea back in early 2018 (ropensci/drake#206 and https://github.com/lbusett/draketest) but traction seems to have waned for now.

[lbusett]

Yes, I did some preliminary work on that, but then unfortunately I was not able to bring it any further.

For reference, what I was struggling with at the time was in "recognizing" the dependencies of the various tests to the different functions in a package (so that a change in a function led to invalidation of the corresponding test results), and in scraping somehow the contents of the various test files, to allow each testthat::expect_.... to become a separate target.

[wlandau]

For reference, what I was struggling with at the time was in "recognizing" the dependencies of the various tests to the different functions in a package (so that a change in a function led to invalidation of the corresponding test results)...

Yeah, there are some counterintuitive requirements for this. For one, we need expose_imports() to tell drake to look in the package for functions that change.

...and in scraping somehow the contents of the various test files, to allow each testthat::expect_.... to become a separate target.

What if each test_that() call is a target? Seems a bit more natural. Related: https://books.ropensci.org/drake/plans.html#how-to-choose-good-targets.