Unable to test a Flask app with default (rewritting) assertions #317
Description
Originally reported by: Sean Lynch (BitBucket: techniq, GitHub: techniq)
Due to how Flask determines it's instance_path (http://flask.pocoo.org/docs/config/#instance-folders), py.test will throw the following error on a simple test
Test
#!python
from flask import Flask
def test_example():
app = Flask(__name__)
assert True
Results / error
#!python
def test_example():
> app = Flask(__name__)
test_flask.py:5:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
self = <flask.app.Flask object at 0x10fd1e810>, import_name = 'test_flask', static_path = None, static_url_path = None
static_folder = 'static', template_folder = 'templates', instance_path = None, instance_relative_config = False
def __init__(self, import_name, static_path=None, static_url_path=None,
static_folder='static', template_folder='templates',
instance_path=None, instance_relative_config=False):
_PackageBoundObject.__init__(self, import_name,
template_folder=template_folder)
if static_path is not None:
from warnings import warn
warn(DeprecationWarning('static_path is now called '
'static_url_path'), stacklevel=2)
static_url_path = static_path
if static_url_path is not None:
self.static_url_path = static_url_path
if static_folder is not None:
self.static_folder = static_folder
if instance_path is None:
> instance_path = self.auto_find_instance_path()
../../../.virtualenvs/pytest-flask/lib/python2.7/site-packages/flask/app.py:303:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
self = <flask.app.Flask object at 0x10fd1e810>
def auto_find_instance_path(self):
"""Tries to locate the instance path if it was not provided to the
constructor of the application class. It will basically calculate
the path to a folder named ``instance`` next to your main file or
the package.
.. versionadded:: 0.8
"""
> prefix, package_path = find_package(self.import_name)
../../../.virtualenvs/pytest-flask/lib/python2.7/site-packages/flask/app.py:608:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
import_name = 'test_flask'
def find_package(import_name):
"""Finds a package and returns the prefix (or None if the package is
not installed) as well as the folder that contains the package or
module as a tuple. The package path returned is the module that would
have to be added to the pythonpath in order to make it possible to
import the module. The prefix is the path below which a UNIX like
folder structure exists (lib, share etc.).
"""
root_mod_name = import_name.split('.')[0]
loader = pkgutil.get_loader(root_mod_name)
if loader is None or import_name == '__main__':
# import name is not found, or interactive/main module
package_path = os.getcwd()
else:
# For .egg, zipimporter does not have get_filename until Python 2.7.
if hasattr(loader, 'get_filename'):
filename = loader.get_filename(root_mod_name)
elif hasattr(loader, 'archive'):
# zipimporter's loader.archive points to the .egg or .zip
# archive filename is dropped in call to dirname below.
filename = loader.archive
else:
# At least one loader is missing both get_filename and archive:
# Google App Engine's HardenedModulesHook
#
# Fall back to imports.
__import__(import_name)
filename = sys.modules[import_name].__file__
package_path = os.path.abspath(os.path.dirname(filename))
# package_path ends with __init__.py for a package
> if loader.is_package(root_mod_name):
E AttributeError: 'AssertionRewritingHook' object has no attribute 'is_package'
The solution is simple (as outlined in the docs: http://pytest.org/latest/assert.html#advanced-assertion-introspection), pass assert=reinterp or assert=plain when running the test.
While not a major issue, it would be great if py.test could test a Flask app without needing to know this knowledge, either by gracefully degrading assertions from module rewriting to reinterp by default, or somehow fixing the root issue of module rewriting with what Flask expects.
Thoughts?