Add expect_*_forwarded

DESCRIPTION

@@ -55,4 +55,4 @@ Config/testthat/parallel: true
 Config/testthat/start-first: watcher, parallel*
 Encoding: UTF-8
 Roxygen: list(markdown = TRUE, r6 = FALSE)
-RoxygenNote: 7.2.3
+RoxygenNote: 7.3.1

NAMESPACE

@@ -84,6 +84,7 @@ export(expect_equal)
 export(expect_equal_to_reference)
 export(expect_equivalent)
 export(expect_error)
+export(expect_error_forwarded)
 export(expect_failure)
 export(expect_false)
 export(expect_gt)
@@ -102,6 +103,7 @@ export(expect_lte)
 export(expect_mapequal)
 export(expect_match)
 export(expect_message)
+export(expect_message_forwarded)
 export(expect_more_than)
 export(expect_named)
 export(expect_no_condition)
@@ -130,6 +132,7 @@ export(expect_type)
 export(expect_vector)
 export(expect_visible)
 export(expect_warning)
+export(expect_warning_forwarded)
 export(expectation)
 export(fail)
 export(find_test_scripts)

NEWS.md

@@ -1,5 +1,11 @@
 # testthat (development version)
 
+* Add new error, warning, and message capturing expectations for conditions from
+  other packages.  `expect_error_forwarded()`, `expect_warning_forwarded()`, and
+  `expect_message_forwarded()` capture errors, warnings, and messages that come
+  from other code to match the message that is not in the control of the package
+  being tested (@billdenney, #1927).
+
 # testthat 3.2.1
 
 * Fix incorrect format string detected by latest R-devel. Fix thanks to 

R/expect-condition-forwarded.R

@@ -0,0 +1,90 @@
+#' Does code throw an error, warning, or message that is the same as another?
+#'
+#' @description
+#' `expect_error_forwarded()`, `expect_warning_forwarded()`, and
+#' `expect_message_forwarded()`, check that code throws an error, warning,
+#' message, or condition with a message that matches an `expected` value from an
+#' example.  These functions are useful to test that a condition matches one
+#' from another package that you do not control.
+#'
+#' @export
+#' @family expectations
+#' @inheritParams expect_that
+#' @param expected A call that causes the expected error, warning, or message.
+#'   It is usually a call to another package than the one being tested.
+#' @return The value of the first argument
+#' @examples
+#' myfun <- function(x) {
+#'   stopifnot(length(x) == 1)
+#' }
+#'
+#' expect_error_forwarded(
+#'   myfun(x = 1:2),
+#'   {
+#'     x <- 1:2
+#'     stopifnot(length(x) == 1)
+#'   }
+#' )
+expect_error_forwarded <- function(object, expected, label = NULL) {
+  message <- error_message(expected)
+  expect_error({{ object }}, regexp = message, fixed = TRUE, label = label)
+}
+
+#' @export
+#' @rdname expect_error_forwarded
+expect_warning_forwarded <- function(object, expected, label = NULL) {
+  message <- warning_message(expected)
+  expect_warning({{ object }}, regexp = message, fixed = TRUE, label = label)
+}
+
+#' @export
+#' @rdname expect_error_forwarded
+expect_message_forwarded <- function(object, expected, label = NULL) {
+  message <- message_message(expected)
+  expect_message({{ object }}, regexp = message, fixed = TRUE, label = label)
+}
+
+error_message <- function(code) {
+  out <- tryCatch(
+    {
+      code
+      NULL
+    },
+    error = function(e) conditionMessage(e)
+  )
+  if (is.null(out)) {
+    stop("No error thrown")
+  } else {
+    out
+  }
+}
+
+warning_message <- function(code) {
+  out <- tryCatch(
+    {
+      code
+      NULL
+    },
+    warning = function(e) conditionMessage(e)
+  )
+  if (is.null(out)) {
+    stop("No warning thrown")
+  } else {
+    out
+  }
+}
+
+message_message <- function(code) {
+  out <- tryCatch(
+    {
+      code
+      NULL
+    },
+    message = function(e) conditionMessage(e)
+  )
+  if (is.null(out)) {
+    stop("No message thrown")
+  } else {
+    out
+  }
+}

R/expect-condition.R

@@ -6,6 +6,10 @@
 #' or condition with a message that matches `regexp`, or a class that inherits
 #' from `class`. See below for more details.
 #'
+#' If you need to test that an error, warning, or message is the same as one
+#' given by another package, then see the [expect_error_forwarded()],
+#' [expect_warning_forwarded()], and [expect_message_forwarded()] functions.
+#'
 #' In the 3rd edition, these functions match (at most) a single condition. All
 #' additional and non-matching (if `regexp` or `class` are used) conditions
 #' will bubble up outside the expectation. If these additional conditions

_pkgdown.yml

@@ -38,6 +38,7 @@ reference:
   - expect_invisible
   - expect_output
   - expect_silent
+  - expect_error_forwarded
   - local_reproducible_output
 
 - title: Snapshot testing