# Copyright 2012 OpenStack Foundation
# All Rights Reserved.
#
#    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 atexit
import os
import sys

import debtcollector.moves
import fixtures
from oslo_log import log as logging
import six
import testtools

from tempest import clients
from tempest.common import credentials_factory as credentials
from tempest.common import utils
from tempest import config
from tempest.lib.common import cred_client
from tempest.lib.common import fixed_network
from tempest.lib.common import validation_resources as vr
from tempest.lib import decorators
from tempest.lib import exceptions as lib_exc

LOG = logging.getLogger(__name__)

CONF = config.CONF

# TODO(oomichi): This test.idempotent_id should be removed after all projects
# switch to use decorators.idempotent_id.
idempotent_id = debtcollector.moves.moved_function(
    decorators.idempotent_id, 'idempotent_id', __name__,
    version='Mitaka', removal_version='?')


attr = debtcollector.moves.moved_function(
    decorators.attr, 'attr', __name__,
    version='Pike', removal_version='?')


services = debtcollector.moves.moved_function(
    utils.services, 'services', __name__,
    version='Pike', removal_version='?')


requires_ext = debtcollector.moves.moved_function(
    utils.requires_ext, 'requires_ext', __name__,
    version='Pike', removal_version='?')


is_extension_enabled = debtcollector.moves.moved_function(
    utils.is_extension_enabled, 'is_extension_enabled', __name__,
    version='Pike', removal_version='?')

at_exit_set = set()


def validate_tearDownClass():
    if at_exit_set:
        LOG.error(
            "tearDownClass does not call the super's "
            "tearDownClass in these classes: \n"
            + str(at_exit_set))


atexit.register(validate_tearDownClass)


class BaseTestCase(testtools.testcase.WithAttributes,
                   testtools.TestCase):
    """The test base class defines Tempest framework for class level fixtures.

    `setUpClass` and `tearDownClass` are defined here and cannot be overwritten
    by subclasses (enforced via hacking rule T105).

    Set-up is split in a series of steps (setup stages), which can be
    overwritten by test classes. Set-up stages are:
    - skip_checks
    - setup_credentials
    - setup_clients
    - resource_setup

    Tear-down is also split in a series of steps (teardown stages), which are
    stacked for execution only if the corresponding setup stage had been
    reached during the setup phase. Tear-down stages are:
    - clear_credentials (defined in the base test class)
    - resource_cleanup
    """

    setUpClassCalled = False

    # NOTE(andreaf) credentials holds a list of the credentials to be allocated
    # at class setup time. Credential types can be 'primary', 'alt', 'admin' or
    # a list of roles - the first element of the list being a label, and the
    # rest the actual roles
    credentials = []

    # Network resources to be provisioned for the requested test credentials.
    # Only used with the dynamic credentials provider.
    _network_resources = {}

    # Stack of resource cleanups
    _class_cleanups = []

    # Resources required to validate a server using ssh
    _validation_resources = {}

    # NOTE(sdague): log_format is defined inline here instead of using the oslo
    # default because going through the config path recouples config to the
    # stress tests too early, and depending on testr order will fail unit tests
    log_format = ('%(asctime)s %(process)d %(levelname)-8s '
                  '[%(name)s] %(message)s')

    # Client manager class to use in this test case.
    client_manager = clients.Manager

    # A way to adjust slow test classes
    TIMEOUT_SCALING_FACTOR = 1

    @classmethod
    def _reset_class(cls):
        cls.__setup_credentials_called = False
        cls.__resource_cleaup_called = False
        cls.__skip_checks_called = False
        cls._class_cleanups = []

    @classmethod
    def setUpClass(cls):
        # Reset state
        cls._reset_class()
        # It should never be overridden by descendants
        if hasattr(super(BaseTestCase, cls), 'setUpClass'):
            super(BaseTestCase, cls).setUpClass()
        cls.setUpClassCalled = True
        # Stack of (name, callable) to be invoked in reverse order at teardown
        cls.teardowns = []
        # All the configuration checks that may generate a skip
        cls.skip_checks()
        if not cls.__skip_checks_called:
            raise RuntimeError("skip_checks for %s did not call the super's "
                               "skip_checks" % cls.__name__)
        try:
            # Allocation of all required credentials and client managers
            cls.teardowns.append(('credentials', cls.clear_credentials))
            cls.setup_credentials()
            if not cls.__setup_credentials_called:
                raise RuntimeError("setup_credentials for %s did not call the "
                                   "super's setup_credentials" % cls.__name__)
            # Shortcuts to clients
            cls.setup_clients()
            # Additional class-wide test resources
            cls.teardowns.append(('resources', cls.resource_cleanup))
            cls.resource_setup()
        except Exception:
            etype, value, trace = sys.exc_info()
            LOG.info("%s raised in %s.setUpClass. Invoking tearDownClass.",
                     etype, cls.__name__)
            cls.tearDownClass()
            try:
                six.reraise(etype, value, trace)
            finally:
                del trace  # to avoid circular refs

    @classmethod
    def tearDownClass(cls):
        # insert pdb breakpoint when pause_teardown is enabled
        if CONF.pause_teardown:
            cls.insert_pdb_breakpoint()
        at_exit_set.discard(cls)
        # It should never be overridden by descendants
        if hasattr(super(BaseTestCase, cls), 'tearDownClass'):
            super(BaseTestCase, cls).tearDownClass()
        # Save any existing exception, we always want to re-raise the original
        # exception only
        etype, value, trace = sys.exc_info()
        # If there was no exception during setup we shall re-raise the first
        # exception in teardown
        re_raise = (etype is None)
        while cls.teardowns:
            name, teardown = cls.teardowns.pop()
            # Catch any exception in tearDown so we can re-raise the original
            # exception at the end
            try:
                teardown()
                if name == 'resources':
                    if not cls.__resource_cleaup_called:
                        raise RuntimeError(
                            "resource_cleanup for %s did not call the "
                            "super's resource_cleanup" % cls.__name__)
            except Exception as te:
                sys_exec_info = sys.exc_info()
                tetype = sys_exec_info[0]
                # TODO(andreaf): Resource cleanup is often implemented by
                # storing an array of resources at class level, and cleaning
                # them up during `resource_cleanup`.
                # In case of failure during setup, some resource arrays might
                # not be defined at all, in which case the cleanup code might
                # trigger an AttributeError. In such cases we log
                # AttributeError as info instead of exception. Once all
                # cleanups are migrated to addClassResourceCleanup we can
                # remove this.
                if tetype is AttributeError and name == 'resources':
                    LOG.info("tearDownClass of %s failed: %s", name, te)
                else:
                    LOG.exception("teardown of %s failed: %s", name, te)
                if not etype:
                    etype, value, trace = sys_exec_info
        # If exceptions were raised during teardown, and not before, re-raise
        # the first one
        if re_raise and etype is not None:
            try:
                six.reraise(etype, value, trace)
            finally:
                del trace  # to avoid circular refs

    def tearDown(self):
        super(BaseTestCase, self).tearDown()
        # insert pdb breakpoint when pause_teardown is enabled
        if CONF.pause_teardown:
            BaseTestCase.insert_pdb_breakpoint()

    @classmethod
    def insert_pdb_breakpoint(cls):
        """Add pdb breakpoint.

        This can help in debugging process, cleaning of resources is
        paused, so they can be examined.
        """
        import pdb
        pdb.set_trace()

    @classmethod
    def skip_checks(cls):
        """Class level skip checks.

        Subclasses verify in here all conditions that might prevent the
        execution of the entire test class. Skipping here prevents any other
        class fixture from being executed i.e. no credentials or other
        resource allocation will happen.

        Tests defined in the test class will no longer appear in test results.
        The `setUpClass` for the entire test class will be marked as SKIPPED
        instead.

        At this stage no test credentials are available, so skip checks
        should rely on configuration alone. This is deliberate since skips
        based on the result of an API call are discouraged.

        The following checks are implemented in `test.py` already:
        - check that alt credentials are available when requested by the test
        - check that admin credentials are available when requested by the test
        - check that the identity version specified by the test is marked as
          enabled in the configuration

        Overriders of skip_checks must always invoke skip_check on `super`
        first.

        Example::

            @classmethod
            def skip_checks(cls):
                super(Example, cls).skip_checks()
                if not CONF.service_available.my_service:
                    skip_msg = ("%s skipped as my_service is not available")
                    raise cls.skipException(skip_msg % cls.__name__)
        """
        cls.__skip_checks_called = True
        identity_version = cls.get_identity_version()
        # setting force_tenant_isolation to True also needs admin credentials.
        if ('admin' in cls.credentials or
                getattr(cls, 'force_tenant_isolation', False)):
            if not credentials.is_admin_available(
                    identity_version=identity_version):
                raise cls.skipException(
                    "Missing Identity Admin API credentials in configuration.")
        if 'alt' in cls.credentials and not credentials.is_alt_available(
                identity_version=identity_version):
            msg = "Missing a 2nd set of API credentials in configuration."
            raise cls.skipException(msg)
        if hasattr(cls, 'identity_version'):
            if cls.identity_version == 'v2':
                if not CONF.identity_feature_enabled.api_v2:
                    raise cls.skipException("Identity api v2 is not enabled")
            elif cls.identity_version == 'v3':
                if not CONF.identity_feature_enabled.api_v3:
                    raise cls.skipException("Identity api v3 is not enabled")

    @classmethod
    def setup_credentials(cls):
        """Allocate credentials and create the client managers from them.

        For every element of credentials param function creates tenant/user,
        Then it creates client manager for that credential.

        Network related tests must override this function with
        set_network_resources() method, otherwise it will create
        network resources(network resources are created in a later step).
        """
        cls.__setup_credentials_called = True
        for credentials_type in cls.credentials:
            # This may raise an exception in case credentials are not available
            # In that case we want to let the exception through and the test
            # fail accordingly
            if isinstance(credentials_type, six.string_types):
                manager = cls.get_client_manager(
                    credential_type=credentials_type)
                setattr(cls, 'os_%s' % credentials_type, manager)
                # NOTE(jordanP): Tempest should use os_primary, os_admin
                # and os_alt throughout its code base but we keep the aliases
                # around for a while for Tempest plugins. Aliases should be
                # removed eventually.
                # Setup some common aliases
                if credentials_type == 'primary':
                    cls.os = debtcollector.moves.moved_read_only_property(
                        'os', 'os_primary', version='Pike',
                        removal_version='Queens')
                    cls.manager =\
                        debtcollector.moves.moved_read_only_property(
                            'manager', 'os_primary', version='Pike',
                            removal_version='Queens')
                if credentials_type == 'admin':
                    cls.os_adm = debtcollector.moves.moved_read_only_property(
                        'os_adm', 'os_admin', version='Pike',
                        removal_version='Queens')
                    cls.admin_manager =\
                        debtcollector.moves.moved_read_only_property(
                            'admin_manager', 'os_admin', version='Pike',
                            removal_version='Queens')
                if credentials_type == 'alt':
                    cls.alt_manager =\
                        debtcollector.moves.moved_read_only_property(
                            'alt_manager', 'os_alt', version='Pike',
                            removal_version='Queens')
            elif isinstance(credentials_type, list):
                manager = cls.get_client_manager(roles=credentials_type[1:],
                                                 force_new=True)
                setattr(cls, 'os_roles_%s' % credentials_type[0], manager)

    @classmethod
    def setup_clients(cls):
        """Create links to the clients into the test object."""
        # TODO(andreaf) There is a fair amount of code that could me moved from
        # base / test classes in here. Ideally tests should be able to only
        # specify which client is `client` and nothing else.
        pass

    @classmethod
    def resource_setup(cls):
        """Class level resource setup for test cases.

        `resource_setup` is invoked once all credentials (and related network
        resources have been provisioned and after client aliases - if any -
        have been defined.

        The use case for `resource_setup` is test optimization: provisioning
        of project-specific "expensive" resources that are not dirtied by tests
        and can thus safely be re-used by multiple tests.

        System wide resources shared by all tests could instead be provisioned
        only once, before the test run.

        Resources provisioned here must be cleaned up during
        `resource_cleanup`. This is best achieved by scheduling a cleanup via
        `addClassResourceCleanup`.

        Some test resources have an asynchronous delete process. It's best
        practice for them to schedule a wait for delete via
        `addClassResourceCleanup` to avoid having resources in process of
        deletion when we reach the credentials cleanup step.

        Example::

            @classmethod
            def resource_setup(cls):
                super(MyTest, cls).resource_setup()
                servers = cls.os_primary.compute.ServersClient()
                # Schedule delete and wait so that we can first delete the
                # two servers and then wait for both to delete
                # Create server 1
                cls.shared_server = servers.create_server()
                # Create server 2. If something goes wrong we schedule cleanup
                # of server 1 anyways.
                try:
                    cls.shared_server2 = servers.create_server()
                    # Wait server 2
                    cls.addClassResourceCleanup(
                        waiters.wait_for_server_termination,
                        servers, cls.shared_server2['id'],
                        ignore_error=False)
                finally:
                    # Wait server 1
                    cls.addClassResourceCleanup(
                        waiters.wait_for_server_termination,
                        servers, cls.shared_server['id'],
                        ignore_error=False)
                        # Delete server 1
                    cls.addClassResourceCleanup(
                        test_utils.call_and_ignore_notfound_exc,
                        servers.delete_server,
                        cls.shared_server['id'])
                    # Delete server 2 (if it was created)
                    if hasattr(cls, 'shared_server2'):
                        cls.addClassResourceCleanup(
                            test_utils.call_and_ignore_notfound_exc,
                            servers.delete_server,
                            cls.shared_server2['id'])
        """
        pass

    @classmethod
    def resource_cleanup(cls):
        """Class level resource cleanup for test cases.

        Resource cleanup processes the stack of cleanups produced by
        `addClassResourceCleanup` and then cleans up validation resources
        if any were provisioned.

        All cleanups are processed whatever the outcome. Exceptions are
        accumulated and re-raised as a `MultipleExceptions` at the end.

        In most cases test cases won't need to override `resource_cleanup`,
        but if they do they must invoke `resource_cleanup` on super.

        Example::

            class TestWithReallyComplexCleanup(test.BaseTestCase):

                @classmethod
                def resource_setup(cls):
                    # provision resource A
                    cls.addClassResourceCleanup(delete_resource, A)
                    # provision resource B
                    cls.addClassResourceCleanup(delete_resource, B)

                @classmethod
                def resource_cleanup(cls):
                    # It's possible to override resource_cleanup but in most
                    # cases it shouldn't be required. Nothing that may fail
                    # should be executed before the call to super since it
                    # might cause resource leak in case of error.
                    super(TestWithReallyComplexCleanup, cls).resource_cleanup()
                    # At this point test credentials are still available but
                    # anything from the cleanup stack has been already deleted.
        """
        cls.__resource_cleaup_called = True
        cleanup_errors = []
        while cls._class_cleanups:
            try:
                fn, args, kwargs = cls._class_cleanups.pop()
                fn(*args, **kwargs)
            except Exception:
                cleanup_errors.append(sys.exc_info())
        if cleanup_errors:
            raise testtools.MultipleExceptions(*cleanup_errors)

    @classmethod
    def addClassResourceCleanup(cls, fn, *arguments, **keywordArguments):
        """Add a cleanup function to be called during resource_cleanup.

        Functions added with addClassResourceCleanup will be called in reverse
        order of adding at the beginning of resource_cleanup, before any
        credential, networking or validation resources cleanup is processed.

        If a function added with addClassResourceCleanup raises an exception,
        the error will be recorded as a test error, and the next cleanup will
        then be run.

        Cleanup functions are always called during the test class tearDown
        fixture, even if an exception occured during setUp or tearDown.
        """
        cls._class_cleanups.append((fn, arguments, keywordArguments))

    def setUp(self):
        super(BaseTestCase, self).setUp()
        if not self.setUpClassCalled:
            raise RuntimeError("setUpClass does not calls the super's"
                               "setUpClass in the "
                               + self.__class__.__name__)
        at_exit_set.add(self.__class__)
        test_timeout = os.environ.get('OS_TEST_TIMEOUT', 0)
        try:
            test_timeout = int(test_timeout) * self.TIMEOUT_SCALING_FACTOR
        except ValueError:
            test_timeout = 0
        if test_timeout > 0:
            self.useFixture(fixtures.Timeout(test_timeout, gentle=True))

        if (os.environ.get('OS_STDOUT_CAPTURE') == 'True' or
                os.environ.get('OS_STDOUT_CAPTURE') == '1'):
            stdout = self.useFixture(fixtures.StringStream('stdout')).stream
            self.useFixture(fixtures.MonkeyPatch('sys.stdout', stdout))
        if (os.environ.get('OS_STDERR_CAPTURE') == 'True' or
                os.environ.get('OS_STDERR_CAPTURE') == '1'):
            stderr = self.useFixture(fixtures.StringStream('stderr')).stream
            self.useFixture(fixtures.MonkeyPatch('sys.stderr', stderr))
        if (os.environ.get('OS_LOG_CAPTURE') != 'False' and
            os.environ.get('OS_LOG_CAPTURE') != '0'):
            self.useFixture(fixtures.LoggerFixture(nuke_handlers=False,
                                                   format=self.log_format,
                                                   level=None))

    @property
    def credentials_provider(self):
        return self._get_credentials_provider()

    @property
    def identity_utils(self):
        """A client that abstracts v2 and v3 identity operations.

        This can be used for creating and tearing down projects in tests. It
        should not be used for testing identity features.
        """
        if CONF.identity.auth_version == 'v2':
            client = self.os_admin.identity_client
            users_client = self.os_admin.users_client
            project_client = self.os_admin.tenants_client
            roles_client = self.os_admin.roles_client
            domains_client = None
        else:
            client = self.os_admin.identity_v3_client
            users_client = self.os_admin.users_v3_client
            project_client = self.os_admin.projects_client
            roles_client = self.os_admin.roles_v3_client
            domains_client = self.os_admin.domains_client

        try:
            domain = client.auth_provider.credentials.project_domain_name
        except AttributeError:
            domain = 'Default'

        return cred_client.get_creds_client(client, project_client,
                                            users_client,
                                            roles_client,
                                            domains_client,
                                            project_domain_name=domain)

    @classmethod
    def get_identity_version(cls):
        """Returns the identity version used by the test class"""
        identity_version = getattr(cls, 'identity_version', None)
        return identity_version or CONF.identity.auth_version

    @classmethod
    def _get_credentials_provider(cls):
        """Returns a credentials provider

        If no credential provider exists yet creates one.
        It always use the configuration value from identity.auth_version,
        since we always want to provision accounts with the current version
        of the identity API.
        """
        if (not hasattr(cls, '_creds_provider') or not cls._creds_provider or
                not cls._creds_provider.name == cls.__name__):
            force_tenant_isolation = getattr(cls, 'force_tenant_isolation',
                                             False)

            cls._creds_provider = credentials.get_credentials_provider(
                name=cls.__name__, network_resources=cls._network_resources,
                force_tenant_isolation=force_tenant_isolation)
        return cls._creds_provider

    @classmethod
    def get_client_manager(cls, credential_type=None, roles=None,
                           force_new=None):
        """Returns an OpenStack client manager

        Returns an OpenStack client manager based on either credential_type
        or a list of roles. If neither is specified, it defaults to
        credential_type 'primary'
        :param credential_type: string - primary, alt or admin
        :param roles: list of roles

        :returns: the created client manager
        :raises skipException: if the requested credentials are not available
        """
        if all([roles, credential_type]):
            msg = "Cannot get credentials by type and roles at the same time"
            raise ValueError(msg)
        if not any([roles, credential_type]):
            credential_type = 'primary'
        cred_provider = cls._get_credentials_provider()
        if roles:
            for role in roles:
                if not cred_provider.is_role_available(role):
                    skip_msg = (
                        "%s skipped because the configured credential provider"
                        " is not able to provide credentials with the %s role "
                        "assigned." % (cls.__name__, role))
                    raise cls.skipException(skip_msg)
            params = dict(roles=roles)
            if force_new is not None:
                params.update(force_new=force_new)
            creds = cred_provider.get_creds_by_roles(**params)
        else:
            credentials_method = 'get_%s_creds' % credential_type
            if hasattr(cred_provider, credentials_method):
                creds = getattr(cred_provider, credentials_method)()
            else:
                raise lib_exc.InvalidCredentials(
                    "Invalid credentials type %s" % credential_type)
        manager = cls.client_manager(credentials=creds.credentials)
        # NOTE(andreaf) Ensure credentials have user and project id fields.
        # It may not be the case when using pre-provisioned credentials.
        manager.auth_provider.set_auth()
        return manager

    @classmethod
    def clear_credentials(cls):
        """Clears creds if set"""
        if hasattr(cls, '_creds_provider'):
            cls._creds_provider.clear_creds()

    @staticmethod
    def _validation_resources_params_from_conf():
        return dict(
            keypair=(CONF.validation.auth_method.lower() == "keypair"),
            floating_ip=(CONF.validation.connect_method.lower() == "floating"),
            security_group=CONF.validation.security_group,
            security_group_rules=CONF.validation.security_group_rules,
            use_neutron=CONF.service_available.neutron,
            ethertype='IPv' + str(CONF.validation.ip_version_for_ssh),
            floating_network_id=CONF.network.public_network_id,
            floating_network_name=CONF.network.floating_network_name)

    @classmethod
    def get_class_validation_resources(cls, os_clients):
        """Provision validation resources according to configuration

        This is a wrapper around `create_validation_resources` from
        `tempest.common.validation_resources` that passes parameters from
        Tempest configuration. Only one instance of class level
        validation resources is managed by the helper, so If resources
        were already provisioned before, existing ones will be returned.

        Resources are returned as a dictionary. They are also scheduled for
        automatic cleanup during class teardown using
        `addClassResourcesCleanup`.

        If `CONF.validation.run_validation` is False no resource will be
        provisioned at all.

        @param os_clients: Clients to be used to provision the resources.
        """
        if not CONF.validation.run_validation:
            return

        if os_clients in cls._validation_resources:
            return cls._validation_resources[os_clients]

        if (CONF.validation.ip_version_for_ssh not in (4, 6) and
                CONF.service_available.neutron):
            msg = "Invalid IP version %s in ip_version_for_ssh. Use 4 or 6"
            raise lib_exc.InvalidConfiguration(
                msg % CONF.validation.ip_version_for_ssh)

        resources = vr.create_validation_resources(
            os_clients,
            **cls._validation_resources_params_from_conf())

        cls.addClassResourceCleanup(
            vr.clear_validation_resources, os_clients,
            use_neutron=CONF.service_available.neutron,
            **resources)
        cls._validation_resources[os_clients] = resources
        return resources

    def get_test_validation_resources(self, os_clients):
        """Returns a dict of validation resources according to configuration

        Initialise a validation resources fixture based on configuration.
        Start the fixture and returns the validation resources.

        If `CONF.validation.run_validation` is False no resource will be
        provisioned at all.

        @param os_clients: Clients to be used to provision the resources.
        """

        params = {}
        # Test will try to use the fixture, so for this to be useful
        # we must return a fixture. If validation is disabled though
        # we don't need to provision anything, which is the default
        # behavior for the fixture.
        if CONF.validation.run_validation:
            params = self._validation_resources_params_from_conf()

        validation = self.useFixture(
            vr.ValidationResourcesFixture(os_clients, **params))
        return validation.resources

    @classmethod
    def set_network_resources(cls, network=False, router=False, subnet=False,
                              dhcp=False):
        """Specify which network resources should be created

        The dynamic credentials provider by default provisions network
        resources for each user/project that is provisioned. This behavior
        can be altered using this method, which allows tests to define which
        specific network resources to be provisioned - none if no parameter
        is specified.

        Credentials are provisioned as part of the class setup fixture,
        during the `setup_credentials` step. For this to be effective this
        helper must be invoked before super's `setup_credentials` is executed.

        @param network
        @param router
        @param subnet
        @param dhcp

        Example::

            @classmethod
            def setup_credentials(cls):
                # Do not setup network resources for this test
                cls.set_network_resources()
                super(MyTest, cls).setup_credentials()
        """
        # If this is invoked after the credentials are setup, it won't take
        # any effect. To avoid this situation, fail the test in case this was
        # invoked too late in the test lifecycle.
        if cls.__setup_credentials_called:
            raise RuntimeError(
                "set_network_resources invoked after setup_credentials on the "
                "super class has been already invoked. For "
                "set_network_resources to have effect please invoke it before "
                "the call to super().setup_credentials")

        # Network resources should be set only once from callers
        # in order to ensure that even if it's called multiple times in
        # a chain of overloaded methods, the attribute is set only
        # in the leaf class.
        if not cls._network_resources:
            cls._network_resources = {
                'network': network,
                'router': router,
                'subnet': subnet,
                'dhcp': dhcp}

    @classmethod
    def get_tenant_network(cls, credentials_type='primary'):
        """Get the network to be used in testing

        :param credentials_type: The type of credentials for which to get the
                                 tenant network

        :return: network dict including 'id' and 'name'
        """
        # Get a manager for the given credentials_type, but at least
        # always fall back on getting the manager for primary credentials
        if isinstance(credentials_type, six.string_types):
            manager = cls.get_client_manager(credential_type=credentials_type)
        elif isinstance(credentials_type, list):
            manager = cls.get_client_manager(roles=credentials_type[1:])
        else:
            manager = cls.get_client_manager()

        # Make sure cred_provider exists and get a network client
        networks_client = manager.compute_networks_client
        cred_provider = cls._get_credentials_provider()
        # In case of nova network, isolated tenants are not able to list the
        # network configured in fixed_network_name, even if they can use it
        # for their servers, so using an admin network client to validate
        # the network name
        if (not CONF.service_available.neutron and
                credentials.is_admin_available(
                    identity_version=cls.get_identity_version())):
            admin_creds = cred_provider.get_admin_creds()
            admin_manager = clients.Manager(admin_creds.credentials)
            networks_client = admin_manager.compute_networks_client
        return fixed_network.get_tenant_network(
            cred_provider, networks_client, CONF.compute.fixed_network_name)

    def assertEmpty(self, items, msg=None):
        """Asserts whether a sequence or collection is empty

        :param items: sequence or collection to be tested
        :param msg: message to be passed to the AssertionError
        :raises AssertionError: when items is not empty
        """
        if msg is None:
            msg = "sequence or collection is not empty: %s" % items
        self.assertFalse(items, msg)

    def assertNotEmpty(self, items, msg=None):
        """Asserts whether a sequence or collection is not empty

        :param items: sequence or collection to be tested
        :param msg: message to be passed to the AssertionError
        :raises AssertionError: when items is empty
        """
        if msg is None:
            msg = "sequence or collection is empty."
        self.assertTrue(items, msg)