try to establish a more standard way to disable network tests

debian/rules

@@ -6,7 +6,8 @@
 
 # This has to be exported to make some magic below work.
 export DH_OPTIONS
-export UNITTEST_NO_NETWORK=1
+# disable network tests in Debian package build
+export PYTEST_USENETWORK=no
 
 %:
 	dh $@  --with=python2,sphinxdoc --buildsystem=pybuild

monkeysign/tests/test_network.py

@@ -33,8 +33,48 @@ from test_lib import TestTimeLimit, AlarmException, find_test_file
 import test_ui
 
 
-@unittest.skipIf('UNITTEST_NO_NETWORK' in os.environ, 'network tests disabled')
+def skipUnlessNetwork():
+    """add a knob to disable network tests
+
+    to disable network tests, use PYTEST_USENETWORK=no. by default, it
+    is assumed there is network access.
+
+    this is mainly to deal with Debian packages that are built in
+    network-less chroots. unfortunately, there is no standard
+    environment in dpkg-buildpackage or ./debian/rules binary that we
+    can rely on to disable tests, so we revert to a custom variable
+    that can hopefully make it up to the pybuild toolchain
+
+    I looked at DEB_BUILD_OPTIONS=network, but that is not standard
+    and only mentionned once here:
+
+    https://lists.debian.org/debian-devel/2009/09/msg00992.html
+
+    DEB_BUILD_OPTIONS is also not set by default, so it's not a good
+    way to detect Debian package builds
+
+    pbuilder uses USENETWORK=no/yes, schroot uses UNSHARE_NET, but
+    those are not standard either, see:
+
+    https://github.com/spotify/dh-virtualenv/issues/77
+    https://github.com/codelibre-net/schroot/blob/2e3d015a759d2b5106e851af34c8d5974d84f18e/lib/schroot/chroot/facet/unshare.cc
+    """
+
+    # by default, we run network tests
+    skip = False
+    reason = ''
+    if 'PYTEST_USENETWORK' in os.environ:
+        skip = 'no' in os.environ.get('PYTEST_USENETWORK', '')
+        reason = 'PYTEST_USENETWORK=no specified in environment'
+    if skip:
+        return unittest.skip('network tests disabled (%s)' % reason)
+    else:
+        return lambda func: func
+
+
+@skipUnlessNetwork()
 class TestGpgNetwork(TestTimeLimit):
+
     """Separate test cases for functions that hit the network
 
 each test needs to run under a specific timeout so we don't wait on
@@ -67,7 +107,7 @@ the network forever"""
         del self.gpg
 
 
-@unittest.skipIf('UNITTEST_NO_NETWORK' in os.environ, 'network tests disabled')
+@skipUnlessNetwork()
 class KeyserverTests(test_ui.BaseTestCase):
     args = ['--keyserver', 'pool.sks-keyservers.net']
     pattern = '7B75921E'