[3.12] gh-106368: Argument clinic tests: improve failure message when tests in `Clini...

gh-106368: Argument clinic tests: improve failure message when tests in `ClinicExternalTests` fail (GH-107364)
(cherry picked from commit 76c26eaca4147ba7e3e8d7379c5a828f0b512a46)

Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>

diff --git a/Lib/test/test_clinic.py b/Lib/test/test_clinic.py
index d1c61b1d401b98d382156cb224f1d4a26bd00c3e..3d740910a57ae657ba6cd0e08b9d5266ab69af59 100644 (file)
--- a/Lib/test/test_clinic.py
+++ b/Lib/test/test_clinic.py
@@ -1360,7 +1360,7 @@ class ClinicExternalTest(TestCase):
         ) as proc:
             proc.wait()
             if expect_success and proc.returncode:
-                self.fail("".join(proc.stderr))
+                self.fail("".join([*proc.stdout, *proc.stderr]))
             stdout = proc.stdout.read()
             stderr = proc.stderr.read()
             # Clinic never writes to stderr.