tests: fix various object and FD leaks

- Prefer instance attributes over local variables - the former ones do
not leak into traceback object and are cleaned up by tests framework.
- Use 'with' syntax for handling files.
- Use subprocess.DEVNULL instead of open('/dev/null') where applicable
- Delete local variables when not needed anymore.

qubes/tests/integ/basic.py

@@ -183,6 +183,10 @@ class TC_01_Properties(qubes.tests.SystemTestCase):
             self.assertEqual(testvm1.firewall.rules,
                             testvm2.firewall.rules)
         finally:
+            try:
+                del firewall
+            except NameError:
+                pass
             try:
                 del testvm1
             except NameError:
@@ -483,29 +487,29 @@ class TC_05_StandaloneVM(qubes.tests.SystemTestCase):
         self.init_default_template()
 
     def test_000_create_start(self):
-        testvm1 = self.app.add_new_vm(qubes.vm.standalonevm.StandaloneVM,
+        self.testvm1 = self.app.add_new_vm(qubes.vm.standalonevm.StandaloneVM,
                                      name=self.make_vm_name('vm1'), label='red')
-        testvm1.features['qrexec'] = True
+        self.testvm1.features['qrexec'] = True
         self.loop.run_until_complete(
-            testvm1.clone_disk_files(self.app.default_template))
+            self.testvm1.clone_disk_files(self.app.default_template))
         self.app.save()
-        self.loop.run_until_complete(testvm1.start())
-        self.assertEqual(testvm1.get_power_state(), "Running")
+        self.loop.run_until_complete(self.testvm1.start())
+        self.assertEqual(self.testvm1.get_power_state(), "Running")
 
     def test_100_resize_root_img(self):
-        testvm1 = self.app.add_new_vm(qubes.vm.standalonevm.StandaloneVM,
+        self.testvm1 = self.app.add_new_vm(qubes.vm.standalonevm.StandaloneVM,
                                      name=self.make_vm_name('vm1'), label='red')
-        testvm1.features['qrexec'] = True
+        self.testvm1.features['qrexec'] = True
         self.loop.run_until_complete(
-            testvm1.clone_disk_files(self.app.default_template))
+            self.testvm1.clone_disk_files(self.app.default_template))
         self.app.save()
         self.loop.run_until_complete(
-            testvm1.storage.resize(testvm1.volumes['root'], 20 * 1024 ** 3))
-        self.assertEqual(testvm1.volumes['root'].size, 20 * 1024 ** 3)
-        self.loop.run_until_complete(testvm1.start())
+            self.testvm1.storage.resize(self.testvm1.volumes['root'], 20 * 1024 ** 3))
+        self.assertEqual(self.testvm1.volumes['root'].size, 20 * 1024 ** 3)
+        self.loop.run_until_complete(self.testvm1.start())
         # new_size in 1k-blocks
         (new_size, _) = self.loop.run_until_complete(
-            testvm1.run_for_stdio('df --output=size /|tail -n 1'))
+            self.testvm1.run_for_stdio('df --output=size /|tail -n 1'))
         # some safety margin for FS metadata
         self.assertGreater(int(new_size.strip()), 19 * 1024 ** 2)
 

qubes/tests/integ/dom0_update.py

@@ -115,7 +115,7 @@ enabled = 1
         self.app.updatevm = self.updatevm
         self.app.save()
         subprocess.call(['sudo', 'rpm', '-e', self.pkg_name],
-                        stderr=open(os.devnull, 'w'))
+                        stderr=subprocess.DEVNULL)
         subprocess.check_call(['sudo', 'rpm', '--import',
                                os.path.join(self.tmpdir, 'pubkey.asc')])
         self.loop.run_until_complete(self.updatevm.start())
@@ -129,10 +129,10 @@ enabled = 1
             del self.repo_proc
         super(TC_00_Dom0UpgradeMixin, self).tearDown()
 
-        subprocess.call(['sudo', 'rpm', '-e', self.pkg_name], stderr=open(
-            os.devnull, 'w'))
+        subprocess.call(['sudo', 'rpm', '-e', self.pkg_name],
+            stderr=subprocess.DEVNULL)
         subprocess.call(['sudo', 'rpm', '-e', 'gpg-pubkey-{}'.format(
-            self.keyid)], stderr=open(os.devnull, 'w'))
+            self.keyid)], stderr=subprocess.DEVNULL)
 
         for pkg in os.listdir(self.tmpdir):
             if pkg.endswith('.rpm'):
@@ -171,17 +171,18 @@ Test package
             ['rpm', '--quiet', '--define=_gpg_path {}'.format(dir),
              '--define=_gpg_name {}'.format("Qubes test"),
              '--addsign', pkg_path],
-            stdin=open(os.devnull),
-            stdout=open(os.devnull, 'w'),
+            stdin=subprocess.DEVNULL,
+            stdout=subprocess.DEVNULL,
             stderr=subprocess.STDOUT)
         subprocess.check_call(['sudo', 'chmod', 'go+rw', '/dev/tty'])
         return pkg_path
 
     def send_pkg(self, filename):
-        self.loop.run_until_complete(self.updatevm.run_for_stdio(
-            'mkdir -p /tmp/repo; cat > /tmp/repo/{}'.format(
-                os.path.basename(filename)),
-            input=open(filename, 'rb').read()))
+        with open(filename, 'rb') as f_pkg:
+            self.loop.run_until_complete(self.updatevm.run_for_stdio(
+                'mkdir -p /tmp/repo; cat > /tmp/repo/{}'.format(
+                    os.path.basename(filename)),
+                input=f_pkg.read()))
         try:
             self.loop.run_until_complete(
                 self.updatevm.run_for_stdio('cd /tmp/repo; createrepo .'))
@@ -229,11 +230,11 @@ Test package
         del proc
 
         retcode = subprocess.call(['rpm', '-q', '{}-1.0'.format(
-            self.pkg_name)], stdout=open(os.devnull, 'w'))
+            self.pkg_name)], stdout=subprocess.DEVNULL)
         self.assertEqual(retcode, 1, 'Package {}-1.0 still installed after '
                                      'update'.format(self.pkg_name))
         retcode = subprocess.call(['rpm', '-q', '{}-2.0'.format(
-            self.pkg_name)], stdout=open(os.devnull, 'w'))
+            self.pkg_name)], stdout=subprocess.DEVNULL)
         self.assertEqual(retcode, 0, 'Package {}-2.0 not installed after '
                                      'update'.format(self.pkg_name))
         self.assertFalse(os.path.exists(self.update_flag_path),
@@ -350,7 +351,7 @@ Test package
         del proc
 
         retcode = subprocess.call(['rpm', '-q', '{}-1.0'.format(
-            self.pkg_name)], stdout=open('/dev/null', 'w'))
+            self.pkg_name)], stdout=subprocess.DEVNULL)
         self.assertEqual(retcode, 1,
                          'Package {}-1.0 installed although '
                          'signature is invalid'.format(self.pkg_name))
@@ -358,7 +359,7 @@ Test package
     def test_030_install_unsigned(self):
         filename = self.create_pkg(self.tmpdir, self.pkg_name, '1.0')
         subprocess.check_call(['rpm', '--delsign', filename],
-                              stdout=open(os.devnull, 'w'),
+                              stdout=subprocess.DEVNULL,
                               stderr=subprocess.STDOUT)
         self.send_pkg(filename)
 
@@ -378,7 +379,7 @@ Test package
         del proc
 
         retcode = subprocess.call(['rpm', '-q', '{}-1.0'.format(
-            self.pkg_name)], stdout=open('/dev/null', 'w'))
+            self.pkg_name)], stdout=subprocess.DEVNULL)
         self.assertEqual(retcode, 1,
                          'UNSIGNED package {}-1.0 installed'.format(self.pkg_name))
 

qubes/tests/integ/storage.py

@@ -46,6 +46,12 @@ class StorageTestMixin(object):
         self.init_pool()
         self.app.save()
 
+    def tearDown(self):
+        del self.vm1
+        del self.vm2
+        del self.pool
+        super(StorageTestMixin, self).tearDown()
+
     def init_pool(self):
         ''' Initialize storage pool to be tested, store it in self.pool'''
         raise NotImplementedError
@@ -65,8 +71,10 @@ class StorageTestMixin(object):
         }
         testvol = self.vm1.storage.init_volume('testvol', volume_config)
         coro_maybe = testvol.create()
+        del testvol
         if asyncio.iscoroutine(coro_maybe):
             yield from coro_maybe
+        del coro_maybe
         self.app.save()
         yield from (self.vm1.start())
 
@@ -98,8 +106,10 @@ class StorageTestMixin(object):
         }
         testvol = self.vm1.storage.init_volume('testvol', volume_config)
         coro_maybe = testvol.create()
+        del testvol
         if asyncio.iscoroutine(coro_maybe):
             yield from coro_maybe
+        del coro_maybe
         self.app.save()
         yield from self.vm1.start()
         # non-volatile image not clean
@@ -133,8 +143,10 @@ class StorageTestMixin(object):
         }
         testvol = self.vm1.storage.init_volume('testvol', volume_config)
         coro_maybe = testvol.create()
+        del testvol
         if asyncio.iscoroutine(coro_maybe):
             yield from coro_maybe
+        del coro_maybe
         self.app.save()
         yield from self.vm1.start()
         # non-volatile image not clean
@@ -167,6 +179,7 @@ class StorageTestMixin(object):
         coro_maybe = testvol.create()
         if asyncio.iscoroutine(coro_maybe):
             yield from coro_maybe
+        del coro_maybe
         volume_config = {
             'pool': self.pool.name,
             'size': size,
@@ -174,10 +187,13 @@ class StorageTestMixin(object):
             'source': testvol.vid,
             'rw': True,
         }
+        del testvol
         testvol_snap = self.vm2.storage.init_volume('testvol', volume_config)
         coro_maybe = testvol_snap.create()
+        del testvol_snap
         if asyncio.iscoroutine(coro_maybe):
             yield from coro_maybe
+        del coro_maybe
         self.app.save()
         yield from self.vm1.start()
         yield from self.vm2.start()
@@ -252,6 +268,7 @@ class StorageTestMixin(object):
         coro_maybe = testvol.create()
         if asyncio.iscoroutine(coro_maybe):
             yield from coro_maybe
+        del coro_maybe
         volume_config = {
             'pool': self.pool.name,
             'size': size,
@@ -259,10 +276,13 @@ class StorageTestMixin(object):
             'source': testvol.vid,
             'rw': True,
         }
+        del testvol
         testvol_snap = self.vm2.storage.init_volume('testvol', volume_config)
         coro_maybe = testvol_snap.create()
+        del testvol_snap
         if asyncio.iscoroutine(coro_maybe):
             yield from coro_maybe
+        del coro_maybe
         self.app.save()
         yield from self.vm2.start()