deb-python-gabbi/gabbi/suite.py
Chris Dent 493c58f76d Handle exceptions when starting fixtures
Some test runners will swallow exceptions and tracebacks that happen
during the start_fixture method of a Fixture. This can lead to a
great deal of confusion when creating new fixtures. This change
ensures that the traceback is made available by forcing an error to
be reported on the first test in the test suite using the fixture.
Additional detail can be found in the comment associated with the
change.

The added test_suite file tests this change by creating a suite with
two tests that use a fixture that will raise an exception in
start_fixture. The test confirms that the right test is errored,
that both are skipped and that the traceback includes expected
information.

Fixes #199
2017-01-17 14:17:16 +00:00

145 lines
5.1 KiB
Python

#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
"""A TestSuite for containing gabbi tests.
This suite has two features: the contained tests are ordered and there
are suite-level fixtures that operate as context managers.
"""
import sys
import unittest
from wsgi_intercept import interceptor
from gabbi import fixture
def noop(*args):
"""A noop method used to disable collected tests."""
pass
class GabbiSuite(unittest.TestSuite):
"""A TestSuite with fixtures.
The suite wraps the tests with a set of nested context managers that
operate as fixtures.
If a fixture raises unittest.case.SkipTest during setup, all the
tests in this suite will be skipped.
"""
def run(self, result, debug=False):
"""Override TestSuite run to start suite-level fixtures.
To avoid exception confusion, use a null Fixture when there
are no fixtures.
"""
fixtures, intercept, host, port, prefix = self._get_intercept()
try:
with fixture.nest([fix() for fix in fixtures]):
if intercept:
with interceptor.Urllib3Interceptor(
intercept, host, port, prefix):
result = super(GabbiSuite, self).run(result, debug)
else:
result = super(GabbiSuite, self).run(result, debug)
except unittest.SkipTest as exc:
for test in self._tests:
result.addSkip(test, str(exc))
# If we have an exception in the nested fixtures, that means
# there's been an exception somewhere in the cycle other
# than a specific test (as that would have been caught
# already), thus from a fixture. If that exception were to
# continue to raise here, then some test runners would
# swallow it and the traceback of the failure would be
# undiscoverable. To ensure the traceback is reported (via
# the testrunner) to a human, the first test in the suite is
# marked as having an error (it's fixture failed) and then
# the entire suite is skipped, and the result stream told
# we're done. If there are no tests (an empty suite) the
# exception is re-raised.
except Exception as exc:
if self._tests:
result.addError(self._tests[0], sys.exc_info())
for test in self._tests:
result.addSkip(test, 'fixture failure')
result.stop()
else:
raise
return result
def start(self, result):
"""Start fixtures when using pytest."""
fixtures, intercept, host, port, prefix = self._get_intercept()
self.used_fixtures = []
try:
for fix in fixtures:
fix_object = fix()
fix_object.__enter__()
self.used_fixtures.append(fix_object)
except unittest.SkipTest as exc:
# Disable the already collected tests that we now wish
# to skip.
for test in self:
test.run = noop
result.addSkip(test, str(exc))
result.addSkip(self, str(exc))
if intercept:
intercept_fixture = interceptor.Urllib3Interceptor(
intercept, host, port, prefix)
intercept_fixture.__enter__()
self.used_fixtures.append(intercept_fixture)
def stop(self):
"""Stop fixtures when using pytest."""
for fix in reversed(self.used_fixtures):
fix.__exit__(None, None, None)
def _get_intercept(self):
fixtures = [fixture.GabbiFixture]
intercept = host = port = prefix = None
try:
first_test = self._find_first_full_test()
fixtures = first_test.fixtures
host = first_test.host
port = first_test.port
prefix = first_test.prefix
intercept = first_test.intercept
# Unbind a passed in WSGI application. During the
# metaclass building process intercept becomes bound.
try:
intercept = intercept.__func__
except AttributeError:
pass
except AttributeError:
pass
return fixtures, intercept, host, port, prefix
def _find_first_full_test(self):
"""Traverse a sparse test suite to find the first HTTPTestCase.
When only some tests are requested empty TestSuites replace the
unrequested tests.
"""
for test in self._tests:
if hasattr(test, 'fixtures'):
return test
raise AttributeError('no fixtures found')