Re-signal unexpected snapshot errors (#1910)

Fixes #1906

NEWS.md

@@ -1,5 +1,9 @@
 # testthat (development version)
 
+* Unexpected errors in `expect_snapshot()` now behave like regular errors;
+  i.e. they terminate evaluation of the entire test and get a traceback 
+  (#1906).
+
 * `local_mocked_bindings()` can now mock any object, not just functions 
   (#1896).
 

R/snapshot.R

@@ -94,7 +94,7 @@ expect_snapshot <- function(x,
     if (error) {
       expect(FALSE, msg, trace = state$error[["trace"]])
     } else {
-      exp_signal(expectation("error", msg, trace = state$error[["trace"]]))
+      cnd_signal(state$error)
     }
     return()
   }

tests/testthat/test-snapshot.R

@@ -142,6 +142,18 @@ test_that("errors and warnings are folded", {
   expect_snapshot(error = TRUE, f())
 })
 
+# I don't know how to test this automatically; wrapping it in another
+# snapshot doesn't capture the behaviour I expected, presumably due to the
+# way that errors bubble up
+# test_that("errors in snapshots behave like regular errors", {
+#   f <- function() g()
+#   g <- function() h()
+#   h <- function() abort("!")
+#
+#   expect_snapshot(f())
+#   expect_snapshot(1 + 1)
+# })
+
 test_that("hint is informative", {
   local_reproducible_output(crayon = TRUE, hyperlinks = TRUE, rstudio = TRUE)