Initial refactoring of charm

.gitignore

@@ -0,0 +1,8 @@
+build/
+.local/
+.testrepository/
+.tox/
+func-results.json
+test-charm/
+**/__pycache__
+.stestr

.stestr.conf

@@ -0,0 +1,3 @@
+[DEFAULT]
+test_path=./unit_tests
+top_dir=./

README.md

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+# Overview
+
+TrilioVault Horizon Plugin is a plugin of TrilioVault which is installed
+on the Openstack and provides TrilioVault UI components.
+
+# Usage
+
+TrilioVault Horizon Plugin is a sub-ordinate charm of openstack-dashboard
+and relies on services from openstack-dashboard.
+
+Steps to deploy the charm:
+
+juju deploy trilio-horizon-plugin
+
+juju deploy openstack-dashboard
+
+juju add-relation trilio-horizon-plugin openstack-dashboard
+
+# Configuration
+
+python-version: "Openstack base python version(2 or 3)"
+
+NOTE - Default value is set to "3". Please ensure to update this based on python version since installing
+       python3 packages on python2 based setup might have unexpected impact.
+
+TrilioVault Packages are downloaded from the repository added in below config parameter. Please change this only if you wish to download
+TrilioVault Packages from a different source.
+
+triliovault-pkg-source: Repository address of triliovault packages
+
+# Contact Information
+
+Trilio Support <support@trilio.com>

copyright

@@ -0,0 +1,16 @@
+Format: http://www.debian.org/doc/packaging-manuals/copyright-format/1.0
+
+Files: *
+Copyright: 2018, Trilio
+License: Apache-2.0
+ 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.

requirements.txt

@@ -0,0 +1,4 @@
+# Requirements to build the charm
+charm-tools
+simplejson
+flake8

src/README.md

@@ -0,0 +1,33 @@
+# Overview
+
+TrilioVault Horizon Plugin is a plugin of TrilioVault which is installed
+on the Openstack and provides TrilioVault UI components.
+
+# Usage
+
+TrilioVault Horizon Plugin is a sub-ordinate charm of openstack-dashboard
+and relies on services from openstack-dashboard.
+
+Steps to deploy the charm:
+
+juju deploy trilio-horizon-plugin
+
+juju deploy openstack-dashboard
+
+juju add-relation trilio-horizon-plugin openstack-dashboard
+
+# Configuration
+
+python-version: "Openstack base python version(2 or 3)"
+
+NOTE - Default value is set to "3". Please ensure to update this based on python version since installing
+       python3 packages on python2 based setup might have unexpected impact.
+
+TrilioVault Packages are downloaded from the repository added in below config parameter. Please change this only if you wish to download
+TrilioVault Packages from a different source.
+
+triliovault-pkg-source: Repository address of triliovault packages
+
+# Contact Information
+
+Trilio Support <support@trilio.com>

src/config.yaml

@@ -0,0 +1,9 @@
+options:
+  python-version:
+    type: int
+    default: 3
+    description: Openstack base python version(2 or 3)
+  triliovault-pkg-source:
+    type: string
+    default: "deb [trusted=yes] https://apt.fury.io/triliodata-3-4/ /"
+    description: Repository address of triliovault packages

src/copyright

@@ -0,0 +1,16 @@
+Format: http://www.debian.org/doc/packaging-manuals/copyright-format/1.0
+
+Files: *
+Copyright: 2018, Trilio
+License: Apache-2.0
+ 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.

src/files/trilio/panels/tvault_admin_panel.py

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+# The slug of the panel to be added to HORIZON_CONFIG. Required.
+PANEL = "workloads_admin"
+# The slug of the dashboard the PANEL associated with. Required.
+PANEL_DASHBOARD = "admin"
+# The slug of the panel group the PANEL is associated with.
+PANEL_GROUP = "backups-admin"
+# Python panel class of the PANEL to be added.
+ADD_PANEL = "dashboards.workloads_admin.panel.Workloads_admin"
+ADD_INSTALLED_APPS = ["dashboards"]
+DISABLED = False

src/files/trilio/panels/tvault_admin_panel_group.py

@@ -0,0 +1,8 @@
+from django.utils.translation import ugettext_lazy as _
+
+# The slug of the panel group to be added to HORIZON_CONFIG. Required.
+PANEL_GROUP = "backups-admin"
+# The display name of the PANEL_GROUP. Required.
+PANEL_GROUP_NAME = _("Backups-Admin")
+# The slug of the dashboard the PANEL_GROUP associated with. Required.
+PANEL_GROUP_DASHBOARD = "admin"

src/files/trilio/panels/tvault_panel.py

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+# The slug of the panel to be added to HORIZON_CONFIG. Required.
+PANEL = "workloads"
+# The slug of the dashboard the PANEL associated with. Required.
+PANEL_DASHBOARD = "project"
+# The slug of the panel group the PANEL is associated with.
+PANEL_GROUP = "backups"
+# Python panel class of the PANEL to be added.
+ADD_PANEL = "dashboards.workloads.panel.Workloads"
+DISABLED = False

src/files/trilio/panels/tvault_panel_group.py

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+from django.utils.translation import ugettext_lazy as _
+
+# The slug of the panel group to be added to HORIZON_CONFIG. Required.
+PANEL_GROUP = "backups"
+# The display name of the PANEL_GROUP. Required.
+PANEL_GROUP_NAME = _("Backups")
+# The slug of the dashboard the PANEL_GROUP associated with. Required.
+PANEL_GROUP_DASHBOARD = "project"

src/files/trilio/panels/tvault_settings_panel.py

@@ -0,0 +1,9 @@
+# The slug of the panel to be added to HORIZON_CONFIG. Required.
+PANEL = "settings"
+# The slug of the dashboard the PANEL associated with. Required.
+PANEL_DASHBOARD = "project"
+# The slug of the panel group the PANEL is associated with.
+PANEL_GROUP = "backups"
+# Python panel class of the PANEL to be added.
+ADD_PANEL = "dashboards.settings.panel.Settings"
+DISABLED = False

src/files/trilio/sync_static.py

@@ -0,0 +1,17 @@
+import sys
+import settings
+import subprocess
+
+ls = settings.INSTALLED_APPS
+data = ""
+
+for app in ls:
+    if app != "dashboards":
+        data += "-i " + str(app) + " "
+
+cmd = (
+    "{} /usr/share/openstack-dashboard/manage.py collectstatic"
+    " --noinput {}".format(sys.executable, data)
+)
+
+subprocess.call(cmd, shell=True)

src/files/trilio/templatetags/tvault_filter.py

@@ -0,0 +1,124 @@
+from django import template
+from openstack_dashboard import api
+from openstack_dashboard import policy
+from datetime import datetime
+from django.template.defaultfilters import stringfilter
+import pytz
+
+register = template.Library()
+
+
+@register.filter(name="getusername")
+def get_user_name(user_id, request):
+    user_name = user_id
+    if policy.check((("identity", "identity:get_user"),), request):
+        try:
+            user = api.keystone.user_get(request, user_id)
+            if user:
+                user_name = user.username
+        except Exception:
+            pass
+    return user_name
+
+
+@register.filter(name="getprojectname")
+def get_project_name(project_id, request):
+    project_name = project_id
+    try:
+        project_info = api.keystone.tenant_get(request, project_id, admin=True)
+        if project_info:
+            project_name = project_info.name
+    except Exception:
+        pass
+    return project_name
+
+
+def get_time_zone(request):
+    tz = "UTC"
+    try:
+        tz = request._get_cookies()["django_timezone"]
+    except Exception:
+        try:
+            tz = request.COOKIES["django_timezone"]
+        except Exception:
+            pass
+
+    return tz
+
+
+def get_local_time(record_time, input_format, output_format, tz):
+    """
+    Convert and return the date and time - from GMT to local time
+    """
+    try:
+        if not record_time or record_time is None or record_time == "":
+            return ""
+        else:
+            if not input_format or input_format is None or input_format == "":
+                input_format = "%Y-%m-%dT%H:%M:%S.%f"
+            if (
+                not output_format or
+                output_format is None or
+                output_format == ""
+            ):
+                output_format = "%m/%d/%Y %I:%M:%S %p"
+
+            local_time = datetime.strptime(record_time, input_format)
+            local_tz = pytz.timezone(tz)
+            from_zone = pytz.timezone("UTC")
+            local_time = local_time.replace(tzinfo=from_zone)
+            local_time = local_time.astimezone(local_tz)
+            local_time = datetime.strftime(local_time, output_format)
+            return local_time
+    except Exception:
+        pass
+        return record_time
+
+
+@register.filter(name="gettime")
+def get_time_for_audit(time_stamp, request):
+    display_time = time_stamp
+    try:
+        time_zone_of_ui = get_time_zone(request)
+        display_time = get_local_time(
+            time_stamp,
+            "%I:%M:%S.%f %p - %m/%d/%Y",
+            "%I:%M:%S %p - %m/%d/%Y",
+            time_zone_of_ui,
+        )
+    except Exception:
+        pass
+    return display_time
+
+
+@register.filter(name="getsnapshotquantifier")
+def display_time_quantifier(seconds):
+    intervals = (
+        ("weeks", 604800),  # 60 * 60 * 24 * 7
+        ("days", 86400),  # 60 * 60 * 24
+        ("hours", 3600),  # 60 * 60
+        ("minutes", 60),
+        ("seconds", 1),
+    )
+
+    result = []
+    granularity = 4
+    for name, count in intervals:
+        value = seconds // count
+        if value:
+            seconds -= value * count
+            if value == 1:
+                name = name.rstrip("s")
+            result.append("{} {}".format(value, name))
+        else:
+            # Add a blank if we're in the middle of other values
+            if len(result) > 0:
+                result.append(None)
+    return ", ".join([x for x in result[:granularity] if x is not None])
+
+
+@register.filter(name="custom_split")
+@stringfilter
+def custom_split(value, key):
+    key = int(key)
+    return value.split("_")[key]

src/icon.svg

@@ -0,0 +1,23 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Generator: Adobe Illustrator 22.1.0, SVG Export Plug-In . SVG Version: 6.00 Build 0)  -->
+<svg version="1.1" id="Layer_1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" x="0px" y="0px"
+	 viewBox="0 0 1000 1000" style="enable-background:new 0 0 1000 1000;" xml:space="preserve">
+<style type="text/css">
+	.st0{fill:#77BC1F;}
+	.st1{fill:#FFFFFF;}
+</style>
+<circle class="st0" cx="500" cy="500.9" r="492.5"/>
+<g>
+	<path class="st1" d="M500.1,799.9c79.9,0,153.9-30.2,208.3-85c55-55.4,85-131.1,84.5-213.1c0-167.8-128.6-299.2-292.7-299.2h-33.6
+		v23.1h33.6c151.2,0,269.5,121.3,269.5,276.2c0.6,75.8-27,145.7-77.7,196.8c-50.1,50.3-118.2,78-191.9,78
+		c-153.7,0-269.5-118.3-269.5-275.1c0-68.6,23.7-133.8,66.9-183.7l-16.6-16.5c-47.4,54.4-73.5,125.4-73.5,200.3
+		C207.4,671.7,333.2,799.9,500.1,799.9"/>
+	<path class="st1" d="M500.1,846c92.2,0,177.5-34.8,240.4-98.1c63.4-63.9,98-151.3,97.3-246c0-192.8-147.7-344.4-336.1-345.4h-12.5
+		V48.3L332.2,215l157.1,166.7v-110h10.8c125.8,0,224.4,101,224.4,230c0.4,63.2-22.5,121.5-64.7,163.9c-41.6,41.9-98.4,65-159.7,65
+		c-128,0-224.4-98.4-224.4-229c0-56.2,19.2-109.8,54.2-151.3L313.3,334c-39.3,45.8-60.8,105.3-60.8,167.7
+		c0,143.7,106.4,252.1,247.6,252.1c67.6,0,130.2-25.5,176.1-71.9c46.5-46.9,71.9-110.8,71.4-180.2c0-141.9-108.7-253-247.5-253
+		h-33.9v74.9L364,215l102.2-108.5v73.1h33.9c176.5,0,314.7,141.6,314.7,322.4c0.7,88.6-31.6,170.1-90.7,229.7
+		c-58.4,58.8-137.9,91.2-224,91.2c-179.4,0-314.7-138-314.7-321c0-80.9,28.2-157.6,79.5-216.3l-16.5-16.5
+		c-55.6,63-86.2,145.6-86.2,232.8C162.2,698.1,307.5,846,500.1,846"/>
+</g>
+</svg>

src/layer.yaml

@@ -0,0 +1,7 @@
+includes:
+  - 'layer:openstack'
+  - 'interface:dashboard-plugin'
+options:
+  basic:
+    use_venv: True
+    include_system_packages: True

src/lib/charm/openstack/trilio_horizon_plugin.py

@@ -0,0 +1,97 @@
+# Copyright 2020 Canonical Ltd
+#
+# 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 collections
+import glob
+import os
+import shutil
+import subprocess
+
+import charmhelpers.core.hookenv as hookenv
+import charmhelpers.fetch as fetch
+
+import charms_openstack.charm
+
+
+HORIZON_PATH = "/usr/share/openstack-dashboard"
+MANAGE_PY = os.path.join(HORIZON_PATH, "manage.py")
+
+
+class TrilioHorizonPluginCharm(charms_openstack.charm.OpenStackCharm):
+
+    service_name = name = "trilio-horizon-plugin"
+
+    # First release supported
+    release = "stein"
+
+    required_relations = []
+
+    package_codenames = {
+        "tvault-horizon-plugin": collections.OrderedDict([("3", "stein")]),
+        "python3-horizon-plugin": collections.OrderedDict([("3", "stein")]),
+    }
+
+    def configure_source(self):
+        with open(
+            "/etc/apt/sources.list.d/" "trilio-gemfury-sources.list", "w"
+        ) as tsources:
+            tsources.write(hookenv.config("triliovault-pkg-source"))
+        fetch.apt_update(fatal=True)
+
+    @property
+    def packages(self):
+        if hookenv.config("python-version") == 2:
+            return ["python-workloadmgrclient", "tvault-horizon-plugin"]
+        return ["python3-workloadmgrclient", "python3-tvault-horizon-plugin"]
+
+    # TODO: drop once packaging is updated
+    def install(self):
+        self.configure_source()
+        super().install()
+        self.copy_files()
+        self.collectstatic_and_compress()
+
+    # TODO: drop once packaging is updated
+    def upgrade_charm(self):
+        super().upgrade_charm()
+        self.copy_files()
+        self.collectstatic_and_compress()
+
+    # TODO: drop when package does this
+    def copy_files(self):
+        for panel in glob.glob("src/files/trilio/panels/*"):
+            shutil.copy(
+                panel,
+                os.path.join(
+                    HORIZON_PATH, "openstack_dashboard/local/enabled"
+                ),
+            )
+        for templatetag in glob.glob("src/files/trilio/templatetags/*"):
+            shutil.copy(
+                templatetag,
+                os.path.join(HORIZON_PATH, "openstack_dashboard/templatetags"),
+            )
+        for index_html in glob.glob(
+            "/usr/lib/python*/**/workloads_admin/index.html", recursive=True
+        ):
+            shutil.copy(
+                "src/files/trilio/templates/workload_admin/index.html",
+                index_html,
+            )
+
+    # TODO: drop when package does this
+    def collectstatic_and_compress(self):
+        python = "/usr/bin/python{}".format(hookenv.config("python-version"))
+        subprocess.check_call([python, MANAGE_PY, "collectstatic"])
+        subprocess.check_call([python, MANAGE_PY, "compress", "--force"])

src/metadata.yaml

@@ -0,0 +1,19 @@
+---
+name: trilio-horizon-plugin
+summary: TrilioVault Horizon Plugin
+maintainer: Trilio Support <support@trilio.io>
+description: |
+  Openstack Dashboard - Horizon plugin for TrilioVault
+tags:
+  - openstack
+  - storage
+  - backup
+  - TVMv3.4
+subordinate: true
+series:
+  - xenial
+  - bionic
+requires:
+  dashboard-plugin:
+    interface: dashboard-plugin
+    scope: container

src/reactive/trilio_horizon_plugin_handlers.py

@@ -0,0 +1,19 @@
+# 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 charms_openstack.charm as charm
+
+# This charm's library contains all of the handler code associated with
+# trilio_horizon_plugin
+import charm.openstack.trilio_horizon_plugin as trilio_horizon_plugin  # noqa
+
+charm.use_defaults("charm.installed", "config.changed", "update-status")

src/test-requirements.txt

@@ -0,0 +1,7 @@
+# Unit test requirements
+flake8>=2.2.4,<=2.4.1
+os-testr>=0.4.1
+charms.reactive
+mock>=1.2
+coverage>=3.6
+git+https://github.com/openstack/charms.openstack#egg=charms.openstack

src/tox.ini

@@ -0,0 +1,21 @@
+# tox (https://tox.readthedocs.io/) is a tool for running tests
+# in multiple virtualenvs. This configuration file will run the
+# test suite on all supported python versions. To use it, "pip install tox"
+# and then run "tox" from this directory.
+
+[tox]
+skipsdist = True
+envlist = pep8
+
+[testenv]
+setenv = VIRTUAL_ENV={envdir}
+         PYTHONHASHSEED=0
+         TERM=linux
+         INTERFACE_PATH={toxinidir}/interfaces
+         LAYER_PATH={toxinidir}/layers
+         JUJU_REPOSITORY={toxinidir}/build
+
+[testenv:pep8]
+basepython = python3
+deps = -r{toxinidir}/test-requirements.txt
+commands = flake8 {posargs} reactive

test-requirements.txt

@@ -0,0 +1,7 @@
+# Unit test requirements
+flake8>=2.2.4
+os-testr>=0.4.1
+charms.reactive
+mock>=1.2
+coverage>=3.6
+git+https://github.com/openstack/charms.openstack#egg=charms.openstack

tox.ini

@@ -0,0 +1,92 @@
+# Source charm: ./tox.ini
+# This file is managed centrally by release-tools and should not be modified
+# within individual charm repos.  See the 'global' dir contents for available
+# choices of tox.ini for OpenStack Charms:
+#     https://github.com/openstack-charmers/release-tools
+
+[tox]
+skipsdist = True
+envlist = pep8,py3
+# NOTE: Avoid build/test env pollution by not enabling sitepackages.
+sitepackages = False
+# NOTE: Avoid false positives by not skipping missing interpreters.
+skip_missing_interpreters = False
+
+[testenv]
+setenv = VIRTUAL_ENV={envdir}
+         PYTHONHASHSEED=0
+         TERM=linux
+         LAYER_PATH={toxinidir}/layers
+         INTERFACE_PATH={toxinidir}/interfaces
+         JUJU_REPOSITORY={toxinidir}/build
+passenv = http_proxy https_proxy INTERFACE_PATH LAYER_PATH JUJU_REPOSITORY
+install_command =
+  pip install {opts} {packages}
+deps =
+    -r{toxinidir}/requirements.txt
+
+[testenv:build]
+basepython = python3
+commands =
+    charm-build --log-level DEBUG -o {toxinidir}/build src {posargs}
+
+[testenv:py3]
+basepython = python3
+deps = -r{toxinidir}/test-requirements.txt
+commands = stestr run --slowest {posargs}
+
+[testenv:py35]
+basepython = python3.5
+deps = -r{toxinidir}/test-requirements.txt
+commands = stestr run --slowest {posargs}
+
+[testenv:py36]
+basepython = python3.6
+deps = -r{toxinidir}/test-requirements.txt
+commands = stestr run --slowest {posargs}
+
+[testenv:py37]
+basepython = python3.7
+deps = -r{toxinidir}/test-requirements.txt
+commands = stestr run --slowest {posargs}
+
+[testenv:pep8]
+basepython = python3
+deps = -r{toxinidir}/test-requirements.txt
+commands = flake8 {posargs} src unit_tests
+
+[testenv:cover]
+# Technique based heavily upon
+# https://github.com/openstack/nova/blob/master/tox.ini
+basepython = python3
+deps = -r{toxinidir}/requirements.txt
+       -r{toxinidir}/test-requirements.txt
+setenv =
+    {[testenv]setenv}
+    PYTHON=coverage run
+commands =
+    coverage erase
+    stestr run --slowest {posargs}
+    coverage combine
+    coverage html -d cover
+    coverage xml -o cover/coverage.xml
+    coverage report
+
+[coverage:run]
+branch = True
+concurrency = multiprocessing
+parallel = True
+source =
+    .
+omit =
+    .tox/*
+    */charmhelpers/*
+    unit_tests/*
+
+[testenv:venv]
+basepython = python3
+commands = {posargs}
+
+[flake8]
+# E402 ignore necessary for path append before sys module import in actions
+ignore = E402,W504

unit_tests/__init__.py

@@ -0,0 +1,9 @@
+import sys
+
+sys.path.append("src")
+sys.path.append("src/lib")
+
+# Mock out charmhelpers so that we can test without it.
+import charms_openstack.test_mocks  # noqa
+
+charms_openstack.test_mocks.mock_charmhelpers()

unit_tests/test_horizon_plugin.py

@@ -0,0 +1,120 @@
+# 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 mock
+import reactive.trilio_horizon_plugin_handlers as handlers
+
+import charms_openstack.test_utils as test_utils
+
+_when_args = {}
+_when_not_args = {}
+
+
+def mock_hook_factory(d):
+    def mock_hook(*args, **kwargs):
+        def inner(f):
+            # remember what we were passed.  Note that we can't actually
+            # determine the class we're attached to, as the decorator only gets
+            # the function.
+            try:
+                d[f.__name__].append(dict(args=args, kwargs=kwargs))
+            except KeyError:
+                d[f.__name__] = [dict(args=args, kwargs=kwargs)]
+            return f
+
+        return inner
+
+    return mock_hook
+
+
+class TestDmapiHandlers(test_utils.PatchHelper):
+    @classmethod
+    def setUpClass(cls):
+        cls._patched_when = mock.patch(
+            "charms.reactive.when", mock_hook_factory(_when_args)
+        )
+        cls._patched_when_started = cls._patched_when.start()
+        cls._patched_when_not = mock.patch(
+            "charms.reactive.when_not", mock_hook_factory(_when_not_args)
+        )
+        cls._patched_when_not_started = cls._patched_when_not.start()
+        # force requires to rerun the mock_hook decorator:
+        # try except is Python2/Python3 compatibility as Python3 has moved
+        # reload to importlib.
+        try:
+            reload(handlers)
+        except NameError:
+            import importlib
+
+            importlib.reload(handlers)
+
+    @classmethod
+    def tearDownClass(cls):
+        cls._patched_when.stop()
+        cls._patched_when_started = None
+        cls._patched_when = None
+        cls._patched_when_not.stop()
+        cls._patched_when_not_started = None
+        cls._patched_when_not = None
+        # and fix any breakage we did to the module
+        try:
+            reload(handlers)
+        except NameError:
+            import importlib
+
+            importlib.reload(handlers)
+
+    def setUp(self):
+        self._patches = {}
+        self._patches_start = {}
+
+    def tearDown(self):
+        for k, v in self._patches.items():
+            v.stop()
+            setattr(self, k, None)
+        self._patches = None
+        self._patches_start = None
+
+    def patch(self, obj, attr, return_value=None, side_effect=None):
+        mocked = mock.patch.object(obj, attr)
+        self._patches[attr] = mocked
+        started = mocked.start()
+        started.return_value = return_value
+        started.side_effect = side_effect
+        self._patches_start[attr] = started
+        setattr(self, attr, started)
+
+    def test_registered_hooks(self):
+        # test that the hooks actually registered the relation expressions that
+        # are meaningful for this interface: this is to handle regressions.
+        # The keys are the function names that the hook attaches to.
+        when_patterns = {
+        }
+        when_not_patterns = {
+        }
+        # check the when hooks are attached to the expected functions
+        for t, p in [
+            (_when_args, when_patterns),
+            (_when_not_args, when_not_patterns),
+        ]:
+            for f, args in t.items():
+                # check that function is in patterns
+                self.assertTrue(f in p.keys(), "{} not found".format(f))
+                # check that the lists are equal
+                lists = []
+                for a in args:
+                    lists += a["args"][:]
+                self.assertEqual(
+                    sorted(lists),
+                    sorted(p[f]),
+                    "{}: incorrect state registration".format(f),
+                )