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"""
Testing Plugins
===============
The plugin interface is well-tested enough to safely unit test your
use of its hooks with some level of confidence. However, there is also
a mixin for unittest.TestCase called PluginTester that's designed to
test plugins in their native runtime environment.
Here's a simple example with a do-nothing plugin and a composed suite.
>>> import unittest
>>> from nose.plugins import Plugin, PluginTester
>>> class FooPlugin(Plugin):
... pass
>>> class TestPluginFoo(PluginTester, unittest.TestCase):
... activate = '--with-foo'
... plugins = [FooPlugin()]
... def test_foo(self):
... for line in self.output:
... # i.e. check for patterns
... pass
...
... # or check for a line containing ...
... assert "ValueError" in self.output
... def makeSuite(self):
... class TC(unittest.TestCase):
... def runTest(self):
... raise ValueError("I hate foo")
... return [TC('runTest')]
...
>>> res = unittest.TestResult()
>>> case = TestPluginFoo('test_foo')
>>> _ = case(res)
>>> res.errors
[]
>>> res.failures
[]
>>> res.wasSuccessful()
True
>>> res.testsRun
1
And here is a more complex example of testing a plugin that has extra
arguments and reads environment variables.
>>> import unittest, os
>>> from nose.plugins import Plugin, PluginTester
>>> class FancyOutputter(Plugin):
... name = "fancy"
... def configure(self, options, conf):
... Plugin.configure(self, options, conf)
... if not self.enabled:
... return
... self.fanciness = 1
... if options.more_fancy:
... self.fanciness = 2
... if 'EVEN_FANCIER' in self.env:
... self.fanciness = 3
...
... def options(self, parser, env=os.environ):
... self.env = env
... parser.add_option('--more-fancy', action='store_true')
... Plugin.options(self, parser, env=env)
...
... def report(self, stream):
... stream.write("FANCY " * self.fanciness)
...
>>> class TestFancyOutputter(PluginTester, unittest.TestCase):
... activate = '--with-fancy' # enables the plugin
... plugins = [FancyOutputter()]
... args = ['--more-fancy']
... env = {'EVEN_FANCIER': '1'}
...
... def test_fancy_output(self):
... assert "FANCY FANCY FANCY" in self.output, (
... "got: %s" % self.output)
... def makeSuite(self):
... class TC(unittest.TestCase):
... def runTest(self):
... raise ValueError("I hate fancy stuff")
... return [TC('runTest')]
...
>>> res = unittest.TestResult()
>>> case = TestFancyOutputter('test_fancy_output')
>>> _ = case(res)
>>> res.errors
[]
>>> res.failures
[]
>>> res.wasSuccessful()
True
>>> res.testsRun
1
"""
import re
import sys
from warnings import warn
try:
from io import StringIO
except ImportError:
from io import StringIO
__all__ = ['PluginTester', 'run']
from os import getpid
class MultiProcessFile(object):
"""
helper for testing multiprocessing
multiprocessing poses a problem for doctests, since the strategy
of replacing sys.stdout/stderr with file-like objects then
inspecting the results won't work: the child processes will
write to the objects, but the data will not be reflected
in the parent doctest-ing process.
The solution is to create file-like objects which will interact with
multiprocessing in a more desirable way.
All processes can write to this object, but only the creator can read.
This allows the testing system to see a unified picture of I/O.
"""
def __init__(self):
# per advice at:
# http://docs.python.org/library/multiprocessing.html#all-platforms
self.__master = getpid()
self.__queue = Manager().Queue()
self.__buffer = StringIO()
self.softspace = 0
def buffer(self):
if getpid() != self.__master:
return
from queue import Empty
from collections import defaultdict
cache = defaultdict(str)
while True:
try:
pid, data = self.__queue.get_nowait()
except Empty:
break
if pid == ():
#show parent output after children
#this is what users see, usually
pid = ( 1e100, ) # googol!
cache[pid] += data
for pid in sorted(cache):
#self.__buffer.write( '%s wrote: %r\n' % (pid, cache[pid]) ) #DEBUG
self.__buffer.write( cache[pid] )
def write(self, data):
# note that these pids are in the form of current_process()._identity
# rather than OS pids
from multiprocessing import current_process
pid = current_process()._identity
self.__queue.put((pid, data))
def __iter__(self):
"getattr doesn't work for iter()"
self.buffer()
return self.__buffer
def seek(self, offset, whence=0):
self.buffer()
return self.__buffer.seek(offset, whence)
def getvalue(self):
self.buffer()
return self.__buffer.getvalue()
def __getattr__(self, attr):
return getattr(self.__buffer, attr)
try:
from multiprocessing import Manager
Buffer = MultiProcessFile
except ImportError:
Buffer = StringIO
class PluginTester(object):
"""A mixin for testing nose plugins in their runtime environment.
Subclass this and mix in unittest.TestCase to run integration/functional
tests on your plugin. When setUp() is called, the stub test suite is
executed with your plugin so that during an actual test you can inspect the
artifacts of how your plugin interacted with the stub test suite.
- activate
- the argument to send nosetests to activate the plugin
- suitepath
- if set, this is the path of the suite to test. Otherwise, you
will need to use the hook, makeSuite()
- plugins
- the list of plugins to make available during the run. Note
that this does not mean these plugins will be *enabled* during
the run -- only the plugins enabled by the activate argument
or other settings in argv or env will be enabled.
- args
- a list of arguments to add to the nosetests command, in addition to
the activate argument
- env
- optional dict of environment variables to send nosetests
"""
activate = None
suitepath = None
args = None
env = {}
argv = None
plugins = []
ignoreFiles = None
def makeSuite(self):
"""returns a suite object of tests to run (unittest.TestSuite())
If self.suitepath is None, this must be implemented. The returned suite
object will be executed with all plugins activated. It may return
None.
Here is an example of a basic suite object you can return ::
>>> import unittest
>>> class SomeTest(unittest.TestCase):
... def runTest(self):
... raise ValueError("Now do something, plugin!")
...
>>> unittest.TestSuite([SomeTest()]) # doctest: +ELLIPSIS
<unittest...TestSuite tests=[<...SomeTest testMethod=runTest>]>
"""
raise NotImplementedError
def _execPlugin(self):
"""execute the plugin on the internal test suite.
"""
from nose.config import Config
from nose.core import TestProgram
from nose.plugins.manager import PluginManager
suite = None
stream = Buffer()
conf = Config(env=self.env,
stream=stream,
plugins=PluginManager(plugins=self.plugins))
if self.ignoreFiles is not None:
conf.ignoreFiles = self.ignoreFiles
if not self.suitepath:
suite = self.makeSuite()
self.nose = TestProgram(argv=self.argv, config=conf, suite=suite,
exit=False)
self.output = AccessDecorator(stream)
def setUp(self):
"""runs nosetests with the specified test suite, all plugins
activated.
"""
self.argv = ['nosetests', self.activate]
if self.args:
self.argv.extend(self.args)
if self.suitepath:
self.argv.append(self.suitepath)
self._execPlugin()
class AccessDecorator(object):
stream = None
_buf = None
def __init__(self, stream):
self.stream = stream
stream.seek(0)
self._buf = stream.read()
stream.seek(0)
def __contains__(self, val):
return val in self._buf
def __iter__(self):
return iter(self.stream)
def __str__(self):
return self._buf
def blankline_separated_blocks(text):
"a bunch of === characters is also considered a blank line"
block = []
for line in text.splitlines(True):
block.append(line)
line = line.strip()
if not line or line.startswith('===') and not line.strip('='):
yield "".join(block)
block = []
if block:
yield "".join(block)
def remove_stack_traces(out):
# this regexp taken from Python 2.5's doctest
traceback_re = re.compile(r"""
# Grab the traceback header. Different versions of Python have
# said different things on the first traceback line.
^(?P<hdr> Traceback\ \(
(?: most\ recent\ call\ last
| innermost\ last
) \) :
)
\s* $ # toss trailing whitespace on the header.
(?P<stack> .*?) # don't blink: absorb stuff until...
^(?=\w) # a line *starts* with alphanum.
.*?(?P<exception> \w+ ) # exception name
(?P<msg> [:\n] .*) # the rest
""", re.VERBOSE | re.MULTILINE | re.DOTALL)
blocks = []
for block in blankline_separated_blocks(out):
blocks.append(traceback_re.sub(r"\g<hdr>\n...\n\g<exception>\g<msg>", block))
return "".join(blocks)
def simplify_warnings(out):
warn_re = re.compile(r"""
# Cut the file and line no, up to the warning name
^.*:\d+:\s
(?P<category>\w+): \s+ # warning category
(?P<detail>.+) $ \n? # warning message
^ .* $ # stack frame
""", re.VERBOSE | re.MULTILINE)
return warn_re.sub(r"\g<category>: \g<detail>", out)
def remove_timings(out):
return re.sub(
r"Ran (\d+ tests?) in [0-9.]+s", r"Ran \1 in ...s", out)
def munge_nose_output_for_doctest(out):
"""Modify nose output to make it easy to use in doctests."""
out = remove_stack_traces(out)
out = simplify_warnings(out)
out = remove_timings(out)
return out.strip()
def run(*arg, **kw):
"""
Specialized version of nose.run for use inside of doctests that
test test runs.
This version of run() prints the result output to stdout. Before
printing, the output is processed by replacing the timing
information with an ellipsis (...), removing traceback stacks, and
removing trailing whitespace.
Use this version of run wherever you are writing a doctest that
tests nose (or unittest) test result output.
Note: do not use doctest: +ELLIPSIS when testing nose output,
since ellipses ("test_foo ... ok") in your expected test runner
output may match multiple lines of output, causing spurious test
passes!
"""
from nose import run
from nose.config import Config
from nose.plugins.manager import PluginManager
buffer = Buffer()
if 'config' not in kw:
plugins = kw.pop('plugins', [])
if isinstance(plugins, list):
plugins = PluginManager(plugins=plugins)
env = kw.pop('env', {})
kw['config'] = Config(env=env, plugins=plugins)
if 'argv' not in kw:
kw['argv'] = ['nosetests', '-v']
kw['config'].stream = buffer
# Set up buffering so that all output goes to our buffer,
# or warn user if deprecated behavior is active. If this is not
# done, prints and warnings will either be out of place or
# disappear.
stderr = sys.stderr
stdout = sys.stdout
if kw.pop('buffer_all', False):
sys.stdout = sys.stderr = buffer
restore = True
else:
restore = False
warn("The behavior of nose.plugins.plugintest.run() will change in "
"the next release of nose. The current behavior does not "
"correctly account for output to stdout and stderr. To enable "
"correct behavior, use run_buffered() instead, or pass "
"the keyword argument buffer_all=True to run().",
DeprecationWarning, stacklevel=2)
try:
run(*arg, **kw)
finally:
if restore:
sys.stderr = stderr
sys.stdout = stdout
out = buffer.getvalue()
print(munge_nose_output_for_doctest(out))
def run_buffered(*arg, **kw):
kw['buffer_all'] = True
run(*arg, **kw)
if __name__ == '__main__':
import doctest
doctest.testmod()
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