pallets__flask-5014

Leaderboard / flask-5014

pallets/flask · v2.3 · 8 steps · 54,819 tokens · 99s

resolved

1.00

The task

The bug report the agent was given — plus the gold fix and hidden tests, shown here for reference. The agent saw only the problem statement.

Problem statementgithub issue

Require a non-empty name for Blueprints
Things do not work correctly if a Blueprint is given an empty name (e.g. #4944).
It would be helpful if a `ValueError` was raised when trying to do that.

Gold patchheld back · the reference fix

diff --git a/src/flask/blueprints.py b/src/flask/blueprints.py--- a/src/flask/blueprints.py+++ b/src/flask/blueprints.py@@ -190,6 +190,9 @@ def __init__( root_path=root_path, ) + if not name:+ raise ValueError("'name' may not be empty.")+ if "." in name: raise ValueError("'name' may not contain a dot '.' character.")

Hidden testtest_patch · applied only to grade

diff --git a/tests/test_blueprints.py b/tests/test_blueprints.py--- a/tests/test_blueprints.py+++ b/tests/test_blueprints.py@@ -256,6 +256,11 @@ def test_dotted_name_not_allowed(app, client): flask.Blueprint("app.ui", __name__) +def test_empty_name_not_allowed(app, client):+ with pytest.raises(ValueError):+ flask.Blueprint("", __name__)++ def test_dotted_names_from_app(app, client): test = flask.Blueprint("test", __name__)

1FAIL → PASS

59PASS → PASS

60 / 60green

The agent run

The agent's step-by-step attempt — its reasoning, the tools it called, and the patch it produced.

System promptharness.agent.build_system_prompt

You are an AI coding assistant working inside a code repository that contains a bug. Investigate the code, find the bug, and fix it.

Your working directory is: /testbed
All four tools (read_file, write_file, edit_file, run_bash) already run from that directory. Use plain relative paths; do not prefix shell commands with cd. Fix the bug by editing source files only; do not create or edit test files.

Step 01 tool use

Let me investigate the codebase to understand the Blueprint functionality and find where to add the validation for non-empty names. Let me start by understanding the project structure and finding relevant files.

run_bash{ command: "find /testbed -type f -name \"*.py\" | head -50" }

tool result · run_bash

exitcode: 0 stdout: /testbed/examples/tutorial/flaskr/auth.py /testbed/examples/tutorial/flaskr/blog.py /testbed/examples/tutorial/flaskr/__init__.py /testbed/examples/tutorial/flaskr/db.py /testbed/examples/tutorial/tests/test_factory.py /testbed/examples/tutorial/tests/test_blog.py /testbed/examples/tutorial/tests/conftest.py /testbed/examples/tutorial/tests/test_auth.py /testbed/examples/tutorial/tests/test_db.py /testbed/examples/celery/make_celery.py /testbed/examples/ce …

Step 02 tool use

Let me look for the Blueprint class definition, which is likely in the main Flask source code.

run_bash{ command: "find /testbed -type f -name \"*.py\" | xargs grep -l \"class Blueprint\" 2>/dev/null" }

tool result · run_bash

exitcode: 0 stdout: /testbed/tests/test_async.py /testbed/src/flask/blueprints.py stderr:

Step 03 tool use

Let me look at the Blueprint class in the blueprints.py source file.

read_file{ path: "/testbed/src/flask/blueprints.py" }

tool result · read_file

import os import typing as t from collections import defaultdict from functools import update_wrapper from . import typing as ft from .scaffold import _endpoint_from_view_func from .scaffold import _sentinel from .scaffold import Scaffold from .scaffold import setupmethod if t.TYPE_CHECKING: # pragma: no cover from .app import Flask DeferredSetupFunction = t.Callable[["BlueprintSetupState"], t.Callable] T_after_request = t.TypeVar("T_after_request", bound=ft.AfterRequ …

Step 04 tool use

Now I can see the `Blueprint.__init__` method. Currently it checks for dots in the name: ```python if "." in name: raise ValueError("'name' may not contain a dot '.' character.") ``` But it doesn't check for an empty name. The issue says things don't work correctly if a Blueprint is given an empty name (e.g., issue #4944), and a `ValueError` should be raised when trying to do that. I should add a check for an empty name. The most appropriate place is right before the dot check, and I should raise a `ValueError` with a descriptive message. Let me also check if there are any tests related to this to understand the testing patterns.

Now I can see the issue. In the `Blueprint.__init__` method, there's a check for dots in the name but no check for an empty name. Let me add a `ValueError` for empty names.

edit_file{ path: "/testbed/src/flask/blueprints.py", old_string: " if \".\" in name:\n raise ValueError(\"'name' may not contain a dot '.' character.\")", new_string: " if not name:\n raise ValueError(\"'name' may not be empty.\")\n\n if \".\" in name:\n raise ValueError(\"'name' may not contain a do…" }

tool result · edit_file

File /testbed/src/flask/blueprints.py edited successfully.

Step 05 tool use

Now let me verify the change looks correct by reading the relevant section of the file.

Let me verify the fix looks correct:

read_file{ path: "/testbed/src/flask/blueprints.py", offset: "171", limit: "20" }

tool result · read_file

ERROR: bad arguments for 'read_file': Toolbox.read_file() got an unexpected keyword argument 'offset'

Step 06 tool use

The tool doesn't support offset. Let me just read the file again to verify.

read_file{ path: "/testbed/src/flask/blueprints.py" }

tool result · read_file

Step 07 tool use

The fix looks good. Let me run a quick test to verify it works.

Now let me verify the fix works correctly:

run_bash{ command: "cd /testbed && python -c \"\nfrom flask import Blueprint\n\n# Test that empty name raises ValueError\ntry:\n bp = Blueprint('', 'test')\n print('ERROR: No except…" }

tool result · run_bash

exitcode: 0 stdout: OK: ValueError raised: 'name' may not be empty. OK: Regular blueprint created successfully OK: ValueError raised: 'name' may not contain a dot '.' character. stderr:

Step 08 reasoning

The fix works correctly: 1. Empty name `''` now raises `ValueError: 'name' may not be empty.` 2. Regular names still work 3. Dot in name still raises the existing `ValueError` The fix is minimal and placed right before the dot check in `Blueprint.__init__`, which is the most logical place.

The fix works correctly. Here's what was done: **Problem:** Creating a `Blueprint` with an empty name (e.g., `Blueprint("", __name__)`) didn't raise an error, but caused things to break in confusing ways later. **Fix:** Added a validation check in `Blueprint.__init__` (in `/testbed/src/flask/blueprints.py`) that raises a `ValueError` with the message `"'name' may not be empty."` if an empty string is passed as the blueprint name. The check is placed right before the existing dot-in-name check, so both validations are clearly grouped together: ```python if not name: raise ValueError("'name' may not be empty.") if "." in name: raise ValueError("'name' may not contain a dot '.' character.") ```

Agent diffcaptured before grading

diff --git a/src/flask/blueprints.py b/src/flask/blueprints.pyindex eb50585d..1aa82562 100644--- a/src/flask/blueprints.py+++ b/src/flask/blueprints.py@@ -190,6 +190,9 @@ class Blueprint(Scaffold): root_path=root_path, ) + if not name:+ raise ValueError("'name' may not be empty.")+ if "." in name: raise ValueError("'name' may not contain a dot '.' character.")