Some notes on snapshot cleanup

Fixes #1615

Author: hadley

R/snapshot.R

@@ -53,6 +53,10 @@
 #'   carefully think about your testing strategy to ensure that all important
 #'   variants are covered by automated tests, and ensure that you have a way
 #'   to get snapshot changes out of your CI system and back into the repo.
+#'
+#'   Note that there's no way to declare all possible variants up front which
+#'   means that as soon as you start using variants, you, not testthat, is
+#'   responsible for cleaning up old snapshots.
 #' @param transform Optionally, a function to scrub sensitive or stochastic
 #'   text from the output. Should take a character vector of lines as input
 #'   and return a modified character vector as output.

man/expect_snapshot.Rd

@@ -128,6 +128,8 @@ test_that("bullets", {
 If this is a deliberate change, you can follow the advice in the message and update the snapshots for that file by running `snapshot_accept("pizza")`; otherwise you can fix the bug and your tests will pass once more.
 (You can also accept snapshot for all files with `snapshot_accept()`).
 
+If you delete the test, the corresponding snapshot will be remove the next time you run the tests. If you delete all snapshots in the file, the entire snapshot file will be deleted the next time you run all the tests.
+
 ### Snapshot format
 
 Snapshots are recorded using a subset of markdown.