Fixed #27391 -- Implemented SimpleTestCase.debug().

debug() should bubbled up exceptions if occurring in test, but behave
the same as run() when no exceptions occurred.

1 files changed, 24 insertions, 1 deletions

diff --git a/django/test/testcases.py b/django/test/testcases.py
index 468c0c4fbc..ca5712ee8d 100644
--- a/django/test/testcases.py
+++ b/django/test/testcases.py
@@ -9,6 +9,7 @@ from contextlib import contextmanager
 from copy import copy
 from difflib import get_close_matches
 from functools import wraps
+from unittest.suite import _DebugResult
 from unittest.util import safe_repr
 from urllib.parse import (
     parse_qsl, unquote, urlencode, urljoin, urlparse, urlsplit, urlunparse,
@@ -235,6 +236,21 @@ class SimpleTestCase(unittest.TestCase):
         set up. This means that user-defined Test Cases aren't required to
         include a call to super().setUp().
         """
+        self._setup_and_call(result)
+
+    def debug(self):
+        """Perform the same as __call__(), without catching the exception."""
+        debug_result = _DebugResult()
+        self._setup_and_call(debug_result, debug=True)
+
+    def _setup_and_call(self, result, debug=False):
+        """
+        Perform the following in order: pre-setup, run test, post-teardown,
+        skipping pre/post hooks if test is set to be skipped.
+
+        If debug=True, reraise any errors in setup and use super().debug()
+        instead of __call__() to run the test.
+        """
         testMethod = getattr(self, self._testMethodName)
         skipped = (
             getattr(self.__class__, "__unittest_skip__", False) or
@@ -245,13 +261,20 @@ class SimpleTestCase(unittest.TestCase):
             try:
                 self._pre_setup()
             except Exception:
+                if debug:
+                    raise
                 result.addError(self, sys.exc_info())
                 return
-        super().__call__(result)
+        if debug:
+            super().debug()
+        else:
+            super().__call__(result)
         if not skipped:
             try:
                 self._post_teardown()
             except Exception:
+                if debug:
+                    raise
                 result.addError(self, sys.exc_info())
                 return