+ source /opt/miniconda3/bin/activate
++ _CONDA_ROOT=/opt/miniconda3
++ . /opt/miniconda3/etc/profile.d/conda.sh
+++ export CONDA_EXE=/opt/miniconda3/bin/conda
+++ CONDA_EXE=/opt/miniconda3/bin/conda
+++ export _CE_M=
+++ _CE_M=
+++ export _CE_CONDA=
+++ _CE_CONDA=
+++ export CONDA_PYTHON_EXE=/opt/miniconda3/bin/python
+++ CONDA_PYTHON_EXE=/opt/miniconda3/bin/python
+++ '[' -z '' ']'
+++ export CONDA_SHLVL=0
+++ CONDA_SHLVL=0
+++ '[' -n '' ']'
+++++ dirname /opt/miniconda3/bin/conda
++++ dirname /opt/miniconda3/bin
+++ PATH=/opt/miniconda3/condabin:/opt/miniconda3/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
+++ export PATH
+++ '[' -z '' ']'
+++ PS1=
++ conda activate
++ local cmd=activate
++ case "$cmd" in
++ __conda_activate activate
++ '[' -n '' ']'
++ local ask_conda
+++ PS1=
+++ __conda_exe shell.posix activate
+++ /opt/miniconda3/bin/conda shell.posix activate
++ ask_conda='PS1='\''(base) '\''
export PATH='\''/opt/miniconda3/bin:/opt/miniconda3/condabin:/opt/miniconda3/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin'\''
export CONDA_PREFIX='\''/opt/miniconda3'\''
export CONDA_SHLVL='\''1'\''
export CONDA_DEFAULT_ENV='\''base'\''
export CONDA_PROMPT_MODIFIER='\''(base) '\''
export CONDA_EXE='\''/opt/miniconda3/bin/conda'\''
export _CE_M='\'''\''
export _CE_CONDA='\'''\''
export CONDA_PYTHON_EXE='\''/opt/miniconda3/bin/python'\'''
++ eval 'PS1='\''(base) '\''
export PATH='\''/opt/miniconda3/bin:/opt/miniconda3/condabin:/opt/miniconda3/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin'\''
export CONDA_PREFIX='\''/opt/miniconda3'\''
export CONDA_SHLVL='\''1'\''
export CONDA_DEFAULT_ENV='\''base'\''
export CONDA_PROMPT_MODIFIER='\''(base) '\''
export CONDA_EXE='\''/opt/miniconda3/bin/conda'\''
export _CE_M='\'''\''
export _CE_CONDA='\'''\''
export CONDA_PYTHON_EXE='\''/opt/miniconda3/bin/python'\'''
+++ PS1='(base) '
+++ export PATH=/opt/miniconda3/bin:/opt/miniconda3/condabin:/opt/miniconda3/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
+++ PATH=/opt/miniconda3/bin:/opt/miniconda3/condabin:/opt/miniconda3/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
+++ export CONDA_PREFIX=/opt/miniconda3
+++ CONDA_PREFIX=/opt/miniconda3
+++ export CONDA_SHLVL=1
+++ CONDA_SHLVL=1
+++ export CONDA_DEFAULT_ENV=base
+++ CONDA_DEFAULT_ENV=base
+++ export 'CONDA_PROMPT_MODIFIER=(base) '
+++ CONDA_PROMPT_MODIFIER='(base) '
+++ export CONDA_EXE=/opt/miniconda3/bin/conda
+++ CONDA_EXE=/opt/miniconda3/bin/conda
+++ export _CE_M=
+++ _CE_M=
+++ export _CE_CONDA=
+++ _CE_CONDA=
+++ export CONDA_PYTHON_EXE=/opt/miniconda3/bin/python
+++ CONDA_PYTHON_EXE=/opt/miniconda3/bin/python
++ __conda_hashr
++ '[' -n '' ']'
++ '[' -n '' ']'
++ hash -r
+ conda activate testbed
+ local cmd=activate
+ case "$cmd" in
+ __conda_activate activate testbed
+ '[' -n '' ']'
+ local ask_conda
++ PS1='(base) '
++ __conda_exe shell.posix activate testbed
++ /opt/miniconda3/bin/conda shell.posix activate testbed
+ ask_conda='PS1='\''(testbed) '\''
export PATH='\''/opt/miniconda3/envs/testbed/bin:/opt/miniconda3/condabin:/opt/miniconda3/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin'\''
export CONDA_PREFIX='\''/opt/miniconda3/envs/testbed'\''
export CONDA_SHLVL='\''2'\''
export CONDA_DEFAULT_ENV='\''testbed'\''
export CONDA_PROMPT_MODIFIER='\''(testbed) '\''
export CONDA_PREFIX_1='\''/opt/miniconda3'\''
export CONDA_EXE='\''/opt/miniconda3/bin/conda'\''
export _CE_M='\'''\''
export _CE_CONDA='\'''\''
export CONDA_PYTHON_EXE='\''/opt/miniconda3/bin/python'\'''
+ eval 'PS1='\''(testbed) '\''
export PATH='\''/opt/miniconda3/envs/testbed/bin:/opt/miniconda3/condabin:/opt/miniconda3/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin'\''
export CONDA_PREFIX='\''/opt/miniconda3/envs/testbed'\''
export CONDA_SHLVL='\''2'\''
export CONDA_DEFAULT_ENV='\''testbed'\''
export CONDA_PROMPT_MODIFIER='\''(testbed) '\''
export CONDA_PREFIX_1='\''/opt/miniconda3'\''
export CONDA_EXE='\''/opt/miniconda3/bin/conda'\''
export _CE_M='\'''\''
export _CE_CONDA='\'''\''
export CONDA_PYTHON_EXE='\''/opt/miniconda3/bin/python'\'''
++ PS1='(testbed) '
++ export PATH=/opt/miniconda3/envs/testbed/bin:/opt/miniconda3/condabin:/opt/miniconda3/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
++ PATH=/opt/miniconda3/envs/testbed/bin:/opt/miniconda3/condabin:/opt/miniconda3/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
++ export CONDA_PREFIX=/opt/miniconda3/envs/testbed
++ CONDA_PREFIX=/opt/miniconda3/envs/testbed
++ export CONDA_SHLVL=2
++ CONDA_SHLVL=2
++ export CONDA_DEFAULT_ENV=testbed
++ CONDA_DEFAULT_ENV=testbed
++ export 'CONDA_PROMPT_MODIFIER=(testbed) '
++ CONDA_PROMPT_MODIFIER='(testbed) '
++ export CONDA_PREFIX_1=/opt/miniconda3
++ CONDA_PREFIX_1=/opt/miniconda3
++ export CONDA_EXE=/opt/miniconda3/bin/conda
++ CONDA_EXE=/opt/miniconda3/bin/conda
++ export _CE_M=
++ _CE_M=
++ export _CE_CONDA=
++ _CE_CONDA=
++ export CONDA_PYTHON_EXE=/opt/miniconda3/bin/python
++ CONDA_PYTHON_EXE=/opt/miniconda3/bin/python
+ __conda_hashr
+ '[' -n '' ']'
+ '[' -n '' ']'
+ hash -r
+ cd /testbed
+ git config --global --add safe.directory /testbed
+ cd /testbed
+ git status
On branch main
Changes not staged for commit:
  (use "git add <file>..." to update what will be committed)
  (use "git restore <file>..." to discard changes in working directory)
	modified:   django/utils/dateformat.py
	modified:   tests/utils_tests/test_dateformat.py

no changes added to commit (use "git add" and/or "git commit -a")
+ git show
commit 1ae11a66c7a70ec956fd524dba23933e22b928ed
Author: SWE-bench <setup@swebench.config>
Date:   Wed Sep 10 11:54:37 2025 +0000

    SWE-bench
+ git -c core.fileMode=false diff b1a4b1f0bdf05adbd3dc4dde14228e68da54c1a3
diff --git a/django/utils/dateformat.py b/django/utils/dateformat.py
index 38e89c47bb..8849df51a8 100644
--- a/django/utils/dateformat.py
+++ b/django/utils/dateformat.py
@@ -314,7 +314,7 @@ class DateFormat(TimeFormat):
 
     def Y(self):
         "Year, 4 digits; e.g. '1999'"
-        return self.data.year
+        return str(self.data.year).zfill(4)
 
     def z(self):
         """Day of the year, i.e. 1 to 366."""
diff --git a/tests/utils_tests/test_dateformat.py b/tests/utils_tests/test_dateformat.py
index c6d3ded80f..8b3a0163fa 100644
--- a/tests/utils_tests/test_dateformat.py
+++ b/tests/utils_tests/test_dateformat.py
@@ -179,6 +179,32 @@ class DateFormatTests(SimpleTestCase):
                     expected_date,
                 )
 
+    def test_year_before_1000_Y_format(self):
+        """
+        Test that Y format returns zero-padded four-digit years for years < 1000.
+        Regression test for DateFormat.Y() not being zero-padded.
+        """
+        tests = [
+            (0, '0000'),
+            (1, '0001'),
+            (9, '0009'),
+            (10, '0010'),
+            (99, '0099'),
+            (100, '0100'),
+            (476, '0476'),
+            (999, '0999'),
+            (1000, '1000'),
+            (1979, '1979'),
+            (2023, '2023'),
+            (9999, '9999'),
+        ]
+        for year, expected in tests:
+            with self.subTest(year=year):
+                self.assertEqual(
+                    dateformat.format(datetime(year, 9, 8, 5, 0), 'Y'),
+                    expected,
+                )
+
     def test_twelve_hour_format(self):
         tests = [
             (0, '12'),
+ source /opt/miniconda3/bin/activate
++ _CONDA_ROOT=/opt/miniconda3
++ . /opt/miniconda3/etc/profile.d/conda.sh
+++ export CONDA_EXE=/opt/miniconda3/bin/conda
+++ CONDA_EXE=/opt/miniconda3/bin/conda
+++ export _CE_M=
+++ _CE_M=
+++ export _CE_CONDA=
+++ _CE_CONDA=
+++ export CONDA_PYTHON_EXE=/opt/miniconda3/bin/python
+++ CONDA_PYTHON_EXE=/opt/miniconda3/bin/python
+++ '[' -z x ']'
++ conda activate
++ local cmd=activate
++ case "$cmd" in
++ __conda_activate activate
++ '[' -n '' ']'
++ local ask_conda
+++ PS1='(testbed) '
+++ __conda_exe shell.posix activate
+++ /opt/miniconda3/bin/conda shell.posix activate
++ ask_conda='PS1='\''(base) '\''
export PATH='\''/opt/miniconda3/bin:/opt/miniconda3/condabin:/opt/miniconda3/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin'\''
export CONDA_PREFIX='\''/opt/miniconda3'\''
export CONDA_SHLVL='\''3'\''
export CONDA_DEFAULT_ENV='\''base'\''
export CONDA_PROMPT_MODIFIER='\''(base) '\''
export CONDA_PREFIX_2='\''/opt/miniconda3/envs/testbed'\''
export CONDA_EXE='\''/opt/miniconda3/bin/conda'\''
export _CE_M='\'''\''
export _CE_CONDA='\'''\''
export CONDA_PYTHON_EXE='\''/opt/miniconda3/bin/python'\'''
++ eval 'PS1='\''(base) '\''
export PATH='\''/opt/miniconda3/bin:/opt/miniconda3/condabin:/opt/miniconda3/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin'\''
export CONDA_PREFIX='\''/opt/miniconda3'\''
export CONDA_SHLVL='\''3'\''
export CONDA_DEFAULT_ENV='\''base'\''
export CONDA_PROMPT_MODIFIER='\''(base) '\''
export CONDA_PREFIX_2='\''/opt/miniconda3/envs/testbed'\''
export CONDA_EXE='\''/opt/miniconda3/bin/conda'\''
export _CE_M='\'''\''
export _CE_CONDA='\'''\''
export CONDA_PYTHON_EXE='\''/opt/miniconda3/bin/python'\'''
+++ PS1='(base) '
+++ export PATH=/opt/miniconda3/bin:/opt/miniconda3/condabin:/opt/miniconda3/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
+++ PATH=/opt/miniconda3/bin:/opt/miniconda3/condabin:/opt/miniconda3/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
+++ export CONDA_PREFIX=/opt/miniconda3
+++ CONDA_PREFIX=/opt/miniconda3
+++ export CONDA_SHLVL=3
+++ CONDA_SHLVL=3
+++ export CONDA_DEFAULT_ENV=base
+++ CONDA_DEFAULT_ENV=base
+++ export 'CONDA_PROMPT_MODIFIER=(base) '
+++ CONDA_PROMPT_MODIFIER='(base) '
+++ export CONDA_PREFIX_2=/opt/miniconda3/envs/testbed
+++ CONDA_PREFIX_2=/opt/miniconda3/envs/testbed
+++ export CONDA_EXE=/opt/miniconda3/bin/conda
+++ CONDA_EXE=/opt/miniconda3/bin/conda
+++ export _CE_M=
+++ _CE_M=
+++ export _CE_CONDA=
+++ _CE_CONDA=
+++ export CONDA_PYTHON_EXE=/opt/miniconda3/bin/python
+++ CONDA_PYTHON_EXE=/opt/miniconda3/bin/python
++ __conda_hashr
++ '[' -n '' ']'
++ '[' -n '' ']'
++ hash -r
+ conda activate testbed
+ local cmd=activate
+ case "$cmd" in
+ __conda_activate activate testbed
+ '[' -n '' ']'
+ local ask_conda
++ PS1='(base) '
++ __conda_exe shell.posix activate testbed
++ /opt/miniconda3/bin/conda shell.posix activate testbed
+ ask_conda='PS1='\''(testbed) '\''
export PATH='\''/opt/miniconda3/envs/testbed/bin:/opt/miniconda3/condabin:/opt/miniconda3/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin'\''
export CONDA_PREFIX='\''/opt/miniconda3/envs/testbed'\''
export CONDA_SHLVL='\''4'\''
export CONDA_DEFAULT_ENV='\''testbed'\''
export CONDA_PROMPT_MODIFIER='\''(testbed) '\''
export CONDA_PREFIX_3='\''/opt/miniconda3'\''
export CONDA_EXE='\''/opt/miniconda3/bin/conda'\''
export _CE_M='\'''\''
export _CE_CONDA='\'''\''
export CONDA_PYTHON_EXE='\''/opt/miniconda3/bin/python'\'''
+ eval 'PS1='\''(testbed) '\''
export PATH='\''/opt/miniconda3/envs/testbed/bin:/opt/miniconda3/condabin:/opt/miniconda3/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin'\''
export CONDA_PREFIX='\''/opt/miniconda3/envs/testbed'\''
export CONDA_SHLVL='\''4'\''
export CONDA_DEFAULT_ENV='\''testbed'\''
export CONDA_PROMPT_MODIFIER='\''(testbed) '\''
export CONDA_PREFIX_3='\''/opt/miniconda3'\''
export CONDA_EXE='\''/opt/miniconda3/bin/conda'\''
export _CE_M='\'''\''
export _CE_CONDA='\'''\''
export CONDA_PYTHON_EXE='\''/opt/miniconda3/bin/python'\'''
++ PS1='(testbed) '
++ export PATH=/opt/miniconda3/envs/testbed/bin:/opt/miniconda3/condabin:/opt/miniconda3/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
++ PATH=/opt/miniconda3/envs/testbed/bin:/opt/miniconda3/condabin:/opt/miniconda3/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
++ export CONDA_PREFIX=/opt/miniconda3/envs/testbed
++ CONDA_PREFIX=/opt/miniconda3/envs/testbed
++ export CONDA_SHLVL=4
++ CONDA_SHLVL=4
++ export CONDA_DEFAULT_ENV=testbed
++ CONDA_DEFAULT_ENV=testbed
++ export 'CONDA_PROMPT_MODIFIER=(testbed) '
++ CONDA_PROMPT_MODIFIER='(testbed) '
++ export CONDA_PREFIX_3=/opt/miniconda3
++ CONDA_PREFIX_3=/opt/miniconda3
++ export CONDA_EXE=/opt/miniconda3/bin/conda
++ CONDA_EXE=/opt/miniconda3/bin/conda
++ export _CE_M=
++ _CE_M=
++ export _CE_CONDA=
++ _CE_CONDA=
++ export CONDA_PYTHON_EXE=/opt/miniconda3/bin/python
++ CONDA_PYTHON_EXE=/opt/miniconda3/bin/python
+ __conda_hashr
+ '[' -n '' ']'
+ '[' -n '' ']'
+ hash -r
+ python -m pip install -e .
Obtaining file:///testbed
  Installing build dependencies: started
  Installing build dependencies: finished with status 'done'
  Checking if build backend supports build_editable: started
  Checking if build backend supports build_editable: finished with status 'done'
  Getting requirements to build editable: started
  Getting requirements to build editable: finished with status 'done'
  Preparing editable metadata (pyproject.toml): started
  Preparing editable metadata (pyproject.toml): finished with status 'done'
Requirement already satisfied: asgiref>=3.3.2 in /opt/miniconda3/envs/testbed/lib/python3.8/site-packages (from Django==4.0.dev20250910115437) (3.8.1)
Requirement already satisfied: pytz in /opt/miniconda3/envs/testbed/lib/python3.8/site-packages (from Django==4.0.dev20250910115437) (2024.2)
Requirement already satisfied: sqlparse>=0.2.2 in /opt/miniconda3/envs/testbed/lib/python3.8/site-packages (from Django==4.0.dev20250910115437) (0.5.1)
Requirement already satisfied: typing-extensions>=4 in /opt/miniconda3/envs/testbed/lib/python3.8/site-packages (from asgiref>=3.3.2->Django==4.0.dev20250910115437) (4.12.2)
Building wheels for collected packages: Django
  Building editable for Django (pyproject.toml): started
  Building editable for Django (pyproject.toml): finished with status 'done'
  Created wheel for Django: filename=django-4.0.dev20250910115437-0.editable-py3-none-any.whl size=26106 sha256=df89cfa581335ed7cda597023881fbab3d328572e7d6a9d7eea39fe9fb8dc512
  Stored in directory: /tmp/pip-ephem-wheel-cache-cesdjjhb/wheels/b2/50/f1/218f2e9962a80d01a4b1297698978f9fb3b60056aa24343f24
Successfully built Django
Installing collected packages: Django
  Attempting uninstall: Django
    Found existing installation: Django 4.0.dev20210511071925
    Uninstalling Django-4.0.dev20210511071925:
      Successfully uninstalled Django-4.0.dev20210511071925
Successfully installed Django-4.0.dev20250910115437
WARNING: Running pip as the 'root' user can result in broken permissions and conflicting behaviour with the system package manager, possibly rendering your system unusable.It is recommended to use a virtual environment instead: https://pip.pypa.io/warnings/venv. Use the --root-user-action option if you know what you are doing and want to suppress this warning.
+ git checkout b1a4b1f0bdf05adbd3dc4dde14228e68da54c1a3 tests/utils_tests/test_dateformat.py
Updated 1 path from b940d09f1b
+ git apply -v -
Checking patch tests/utils_tests/test_dateformat.py...
Applied patch tests/utils_tests/test_dateformat.py cleanly.
+ : '>>>>> Start Test Output'
+ ./tests/runtests.py --verbosity 2 --settings=test_sqlite --parallel 1 utils_tests.test_dateformat
test_Y_format_year_before_1000 (utils_tests.test_dateformat.DateFormatTests) ... ok
test_am_pm (utils_tests.test_dateformat.DateFormatTests) ... ok
test_date (utils_tests.test_dateformat.DateFormatTests) ... ok
test_date_formats (utils_tests.test_dateformat.DateFormatTests) ... ok
test_dateformat (utils_tests.test_dateformat.DateFormatTests) ... ok
test_datetime_with_local_tzinfo (utils_tests.test_dateformat.DateFormatTests) ... ok
test_datetime_with_tzinfo (utils_tests.test_dateformat.DateFormatTests) ... ok
test_day_of_year_leap (utils_tests.test_dateformat.DateFormatTests) ... ok
test_empty_format (utils_tests.test_dateformat.DateFormatTests) ... ok
test_epoch (utils_tests.test_dateformat.DateFormatTests) ... ok
test_futuredates (utils_tests.test_dateformat.DateFormatTests) ... ok
test_invalid_time_format_specifiers (utils_tests.test_dateformat.DateFormatTests) ... ok
test_microsecond (utils_tests.test_dateformat.DateFormatTests) ... ok
test_naive_ambiguous_datetime (utils_tests.test_dateformat.DateFormatTests) ... ok
test_naive_datetime (utils_tests.test_dateformat.DateFormatTests) ... ok
test_r_format_with_non_en_locale (utils_tests.test_dateformat.DateFormatTests) ... ok
test_time_formats (utils_tests.test_dateformat.DateFormatTests) ... ok
test_timezones (utils_tests.test_dateformat.DateFormatTests) ... ok
test_twelve_hour_format (utils_tests.test_dateformat.DateFormatTests) ... ok
test_y_format_year_before_1000 (utils_tests.test_dateformat.DateFormatTests) ... ok

----------------------------------------------------------------------
Ran 20 tests in 0.011s

OK
Testing against Django installed in '/testbed/django'
Importing application utils_tests
Found 20 tests.
Skipping setup of unused database(s): default, other.
System check identified no issues (0 silenced).
+ : '>>>>> End Test Output'
+ git checkout b1a4b1f0bdf05adbd3dc4dde14228e68da54c1a3 tests/utils_tests/test_dateformat.py
Updated 1 path from b940d09f1b
