✨ Fix JunitReporter for warnings outside tests ✨ (#2158)

Unprompted, claude also added code to capture warning backtraces, which seems useful.

Fixes #1913

Author: hadley

.claude/settings.local.json

@@ -1,8 +1,10 @@
 {
   "permissions": {
     "allow": [
-      "Bash(find:*)"
+      "Bash(find:*)",
+      "Bash(R:*)"
     ],
     "deny": []
-  }
+  },
+  "$schema": "https://json.schemastore.org/claude-code-settings.json"
 }

CLAUDE.md

@@ -8,15 +8,15 @@ testthat is R's most popular unit testing framework, used by thousands of CRAN p
 
 ## Key Development Commands
 
-### Testing
-- `devtools::test()` or `Ctrl/Cmd+Shift+T` in RStudio - Run all tests
-- `devtools::test_file("tests/testthat/test-filename.R")` - Run tests in a specific file
-- `testthat::test_local()` - Run tests for local source package
-- `testthat::test_package("testthat")` - Run tests for installed package
-- `R CMD check` - Full package check including tests
+General advice:
+* When running R from the console, always run it with `--quiet --vanilla`
+* Always run `air format .` after generating code
+
+### Development tools
 
-### Building and Installation
-- `devtools::load_all()` or `Ctrl/Cmd+Shift+L` - Load package for development
+- `devtools::test()` - Run all tests
+- `devtools::test_file("tests/testthat/test-filename.R")` - Run tests in a specific file
+- `devtools::load_all()` - Load package for development
 - `devtools::document()` - Generate documentation
 - `devtools::check()` - Run R CMD check
 - `devtools::install()` - Install package locally

NEWS.md

@@ -1,5 +1,6 @@
 # testthat (development version)
 
+* `JunitReporter()` no longer fails with `"no applicable method for xml_add_child"` for warnings outside of tests (#1913). Additionally, warnings now save their backtraces.
 * `JunitReporter()` strips ANSI escapes in more placese (#1852, #2032).
 * `try_again()` is now publicised. The first argument is now the number of retries, not tries (#2050).
 * `vignette("custom-expectations)` has been overhauled to make it much clearer how to create high-quality expectations (#2113, #2132, #2072).

R/reporter-junit.R

@@ -108,6 +108,11 @@ JunitReporter <- R6::R6Class(
       time <- self$elapsed_time()
       self$suite_time <- self$suite_time + time
 
+      # If no context was started (e.g., warnings outside tests), create a default one
+      if (is.null(self$suite)) {
+        self$start_context(context %||% "(unknown)")
+      }
+
       # XML node for test case
       name <- test %||% "(unnamed)"
       testcase <- xml2::xml_add_child(
@@ -147,6 +152,9 @@ JunitReporter <- R6::R6Class(
       } else if (expectation_skip(result)) {
         xml2::xml_add_child(testcase, "skipped", message = first_line(result))
         self$skipped <- self$skipped + 1
+      } else if (expectation_warning(result)) {
+        warning_node <- xml2::xml_add_child(testcase, "system-out")
+        xml2::xml_text(warning_node) <- cli::ansi_strip(format(result))
       }
     },
 

tests/testthat/_snaps/reporter-junit.md

@@ -45,7 +45,12 @@
         </testcase>
       </testsuite>
       <testsuite name="Warnings" timestamp="1999:12:31 23:59:59" hostname="nodename" tests="2" skipped="1" failures="0" errors="0" time="0">
-        <testcase time="0" classname="Warnings" name="warnings_get_backtraces"/>
+        <testcase time="0" classname="Warnings" name="warnings_get_backtraces">
+          <system-out>def
+    Backtrace:
+        x
+     1. \-f()</system-out>
+        </testcase>
         <testcase time="0" classname="Warnings" name="warnings_get_backtraces">
           <skipped message="Reason: empty test ('reporters/tests.R:44:1')"/>
         </testcase>

tests/testthat/test-reporter-junit.R

@@ -27,3 +27,17 @@ test_that("ANSI escapes are stripped from all user text in XML", {
 
   expect_no_error(xml2::read_xml(tmp))
 })
+
+test_that("warnings outside context don't cause xml_add_child errors", {
+  skip_if_not_installed("xml2")
+
+  tmp <- withr::local_tempfile(fileext = ".xml")
+  reporter <- JunitReporterMock$new(file = tmp)
+  reporter$start_reporter()
+
+  # This would previously fail with "no applicable method for 'xml_add_child'"
+  expect_no_error({
+    reporter$add_result(NULL, "test", new_expectation("warning", "test"))
+  })
+  reporter$end_reporter()
+})