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Ensure that expect_snapshot() registers restart #2271

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Merged
merged 1 commit into from
Oct 23, 2025
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Ensure that expect_snapshot() registers restart #2271

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2 changes: 1 addition & 1 deletion NEWS.md
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Expand Up @@ -850,7 +850,7 @@ This release mostly focusses on an overhaul of how testthat works with condition

* New `exp_signal()` function is a condition signaller that
implements the testthat protocol (signal with `stop()` if the
expectation is broken, with a `continue_test` restart).
expectation is broken, with a `muffle_expectation` restart).

* Existence of restarts is first checked before invocation. This makes
it possible to signal warnings or messages with a different
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6 changes: 2 additions & 4 deletions R/expect-self-test.R
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Expand Up @@ -11,13 +11,11 @@ capture_success_failure <- function(expr) {
expectation_failure = function(cnd) {
last_failure <<- cnd
n_failure <<- n_failure + 1
# Don't bubble up to any other handlers
invokeRestart("continue_test")
invokeRestart("muffle_expectation")
},
expectation_success = function(cnd) {
n_success <<- n_success + 1
# Don't bubble up to any other handlers
invokeRestart("continue_test")
invokeRestart("muffle_expectation")
}
)

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4 changes: 2 additions & 2 deletions R/expectation.R
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Expand Up @@ -10,7 +10,7 @@
#' optionally subsequence) elements should describe what was actually seen.
#' @inheritParams fail
#' @return An expectation object from either `succeed()` or `fail()`.
#' with a `continue_test` restart.
#' with a `muffle_expectation` restart.
#' @seealso [exp_signal()]
#' @keywords internal
#' @export
Expand Down Expand Up @@ -104,7 +104,7 @@ exp_signal <- function(exp) {
} else {
signalCondition(exp)
},
continue_test = function(e) NULL
muffle_expectation = function(e) NULL
)

invisible(exp)
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7 changes: 6 additions & 1 deletion R/snapshot.R
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Expand Up @@ -131,7 +131,12 @@ expect_snapshot_ <- function(
if (error) {
fail(msg, trace = state$error[["trace"]])
} else {
cnd_signal(state$error)
# This might be a failed expectation, so we need to make sure
# that we can muffle it
withRestarts(
cnd_signal(state$error),
muffle_expectation = function() NULL
)
}
Comment on lines -134 to 140
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I know very little about testthat internals, but is this supposed to be exp_signal(state$error)?

It feels like there should only be 1 place in testthat where you set up withRestarts(muffle_expectation =), and then other places should reuse that helper. Otherwise you end up with weird ad hoc calls like this one.

I'm not totally sure what state$error is though, and if calling exp_signal() on it is appropriate

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state$error could be any error, not just an expectation.

I agree that there shouldn't be multiple places where we have to add this restart, but the condition handling in snapshots is complicated and I know I've got it wrong before, so I don't really want to touch that code. (I just looked back at the blame and it seems like literally every line of that if statement required a different PR to get right 😭). (But I'll take one more look)

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Yeah, I tried again, and it got me into an even weirder state. So I don't think it's worth 100% reasoning through again, and this should be the only place where we need it.

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Sounds fine

return()
}
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3 changes: 1 addition & 2 deletions R/test-that.R
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Expand Up @@ -111,8 +111,7 @@ test_code <- function(code, env, reporter = NULL, skip_on_empty = TRUE) {
handle_expectation <- function(e) {
the$test_expectations <- the$test_expectations + 1L
register_expectation(e, 7)
# Don't bubble up to any other handlers
invokeRestart("continue_test")
invokeRestart("muffle_expectation")
}
handle_warning <- function(e) {
# When options(warn) < 0, warnings are expected to be ignored.
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2 changes: 1 addition & 1 deletion man/expect.Rd
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8 changes: 8 additions & 0 deletions tests/testthat/_snaps/snapshot.md
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Expand Up @@ -104,6 +104,14 @@
Error:
! Expected `print("!")` to throw a error.

# snapshots of failures fail

Code
expect_snapshot(fail())
Condition
Error:
! Failure has been forced

# can capture error/warning messages

This is an error
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4 changes: 4 additions & 0 deletions tests/testthat/test-snapshot.R
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Expand Up @@ -69,6 +69,10 @@ test_that("always checks error status", {
expect_snapshot_failure(expect_snapshot(print("!"), error = TRUE))
})

test_that("snapshots of failures fail", {
expect_snapshot_failure(expect_snapshot(fail()))
})

test_that("can capture error/warning messages", {
expect_snapshot_error(stop("This is an error"))
expect_snapshot_warning(warning("This is a warning"))
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