diskimage-builder/diskimage_builder/block_device/tests/test_state.py
Ian Wienand b85de3cd9e Add state object, rename "results", add unit tests
A couple of things going on, but I think it makes sense to do them
atomically.

The NodeBase.create() argument "results" is the global state
dictionary that will be saved to "state.json", and re-loaded in later
phases and passed to them as the argument "state".  So for
consistency, call this argument "state" (this fits with the change out
to start building the state dictionary earlier in the
PluginBase.__init__() calls).

Since the "state" is a pretty important part of how everything works,
move it into a separate object.  This is treated as essentially a
singleton.  It bundles it nicely together for some added
documentation [1].

We move instantiation of this object out of the generic
BlockDevice.__init__() call and into the actual cmd_* drivers.  This
is because there's two distinct instantiation operations -- creating a
new state (during cmd_create) and loading an existing state (other
cmd_*).  This is also safer -- since we know the cmd_* arguments are
looking for an existing state.json, we will fail if it somehow goes
missing.

To more fully unit test this, some testing plugins and new
entry-points are added.  These add known state values which we check
for.  These should be a good basis for further tests.

[1] as noted, we could probably do some fun things in the future like
make this implement a dictionary and have some saftey features like
r/o keys.

Change-Id: I90eb711b3e9b1ce139eb34bdf3cde641fd06828f
2017-05-30 20:39:00 +10:00

108 lines
3.7 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.
import codecs
import fixtures
import json
import logging
import os
from stevedore import extension
from testtools.matchers import FileExists
import diskimage_builder.block_device.blockdevice as bd
import diskimage_builder.block_device.tests.test_base as tb
from diskimage_builder.block_device.exception import \
BlockDeviceSetupException
logger = logging.getLogger(__name__)
class TestStateBase(tb.TestBase):
def setUp(self):
super(TestStateBase, self).setUp()
# override the extensions to the test extensions
test_extensions = extension.ExtensionManager(
namespace='diskimage_builder.block_device.plugin_test',
invoke_on_load=False)
extensions_fixture = fixtures.MonkeyPatch(
'diskimage_builder.block_device.config._extensions',
test_extensions)
self.useFixture(extensions_fixture)
# status and other bits saved here
self.build_dir = fixtures.TempDir()
self.useFixture(self.build_dir)
class TestState(TestStateBase):
# The the state generation & saving methods
def test_state_create(self):
params = {
'build-dir': self.build_dir.path,
'config': self.get_config_file('cmd_create.yaml')
}
bd_obj = bd.BlockDevice(params)
bd_obj.cmd_init()
bd_obj.cmd_create()
# cmd_create should have persisted this to disk
state_file = os.path.join(self.build_dir.path,
'states', 'block-device',
'state.json')
self.assertThat(state_file, FileExists())
# ensure we see the values put in by the test extensions
# persisted
with codecs.open(state_file, encoding='utf-8', mode='r') as fd:
state = json.load(fd)
self.assertDictEqual(state,
{'test_a': {'value': 'foo',
'value2': 'bar'},
'test_b': {'value': 'baz'}})
# Test state going missing between phases
def test_missing_state(self):
params = {
'build-dir': self.build_dir.path,
'config': self.get_config_file('cmd_create.yaml')
}
bd_obj = bd.BlockDevice(params)
bd_obj.cmd_init()
bd_obj.cmd_create()
# cmd_create should have persisted this to disk
state_file = os.path.join(self.build_dir.path,
'states', 'block-device',
'state.json')
self.assertThat(state_file, FileExists())
# simulate the state somehow going missing, and ensure that
# later calls notice
os.unlink(state_file)
self.assertRaisesRegexp(BlockDeviceSetupException,
"State dump not found",
bd_obj.cmd_cleanup)
self.assertRaisesRegexp(BlockDeviceSetupException,
"State dump not found",
bd_obj.cmd_writefstab)
self.assertRaisesRegexp(BlockDeviceSetupException,
"State dump not found",
bd_obj.cmd_delete)