Misc fixes for failing github workflows

Add separate workflow for testing on Python 3.6 as this
requires an older Ubuntu release.

Fixup unit tests for compatibility with newer versions of mock.

Drop latest/stable functional test targets - this is actually
2.9.x of Juju and is already covered by the 2.9 targets and we
want to avoid suddenly picking up a new Juju version because
this will break with the new approach to version alignment in the
Python module for Juju.

Drop 2.8 functional test target - its broken and we don't really
support this version any longer.

Fixup iptables forwarding issues from LXD containers with a flush
and re-create of rules.

(cherry picked from commit 9277a94)
(cherry picked from commit ee92b9b)
(cherry picked from commit 355ad7a)

.github/workflows/tox.yaml

@@ -5,11 +5,36 @@ on:
   - pull_request
 
 jobs:
+  build_old_versions:
+    runs-on: ubuntu-20.04
+    strategy:
+      matrix:
+        python-version: ['3.6', '3.7']
+
+    steps:
+    - uses: actions/checkout@v1
+    - name: Set up Python ${{ matrix.python-version }}
+      uses: actions/setup-python@v2
+      with:
+        python-version: ${{ matrix.python-version }}
+    - name: Install dependencies
+      run: |
+        python -m pip install --upgrade pip
+        pip install codecov tox tox-gh-actions
+    - name: Lint with tox
+      run: tox -e pep8
+    - name: Test with tox
+      run: tox -e py
+    - name: Codecov
+      run: |
+        set -euxo pipefail
+        codecov --verbose --gcov-glob unit_tests/*
+
   build:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: [3.6, 3.7, 3.8, 3.9]
+        python-version: [3.8, 3.9]
 
     steps:
     - uses: actions/checkout@v1
@@ -35,21 +60,11 @@ jobs:
       fail-fast: false
       matrix:
         juju_channel:
-          - latest/stable
           - 2.9/stable
-          - 2.8/stable
         bundle:
           - first
           - second
           - third
-        exclude:
-          # disable 'first' and 'second' bundles for juju 2.8 since 'magpie'
-          # is not a promulgated charm in the charmstore, only on charmhub
-          # which 2.8 can't talk to.
-          - juju_channel: 2.8/stable
-            bundle: first
-          - juju_channel: 2.8/stable
-            bundle: second
     env:
       TEST_ZAZA_BUG_LP1987332: "on"  # http://pad.lv/1987332
     needs: build
@@ -67,6 +82,8 @@ jobs:
         sudo chmod 666 /var/snap/lxd/common/lxd/unix.socket
         # until Juju provides stable IPv6-support we unfortunately need this
         lxc network set lxdbr0 ipv6.address none
+        sudo iptables -F FORWARD
+        sudo iptables -P FORWARD ACCEPT
         # pull images
         lxc image copy --alias juju/bionic/amd64 --copy-aliases ubuntu-daily:bionic local:
         lxc image copy --alias juju/focal/amd64 --copy-aliases ubuntu-daily:focal local:

unit_tests/test_zaza_model.py

@@ -435,8 +435,9 @@ def test_block_until_auto_reconnect_model_disconnected_sync(self):
         # model.disconnect and model.connect should've each have been called
         # twice, once for run_in_model, and once each for the disconnection.
         self.Model_mock.disconnect.assert_has_calls([mock.call(), mock.call()])
-        self.Model_mock.connect_model.has_calls([mock.call('modelname'),
-                                                 mock.call('modelname')])
+        self.Model_mock.connect_model.assert_has_calls(
+            [mock.call('modelname'), mock.call('testmodel')]
+        )
 
     def test_block_until_auto_reconnect_model_disconnected_async(self):
         self._mocks_for_block_until_auto_reconnect_model(
@@ -450,8 +451,9 @@ async def _async_true():
         # model.disconnect and model.connect should've each have been called
         # twice, once for run_in_model, and once each for the disconnection.
         self.Model_mock.disconnect.assert_has_calls([mock.call(), mock.call()])
-        self.Model_mock.connect_model.has_calls([mock.call('modelname'),
-                                                 mock.call('modelname')])
+        self.Model_mock.connect_model.assert_has_calls(
+            [mock.call('modelname'), mock.call('testmodel')]
+        )
 
     def test_block_until_auto_reconnect_model_blocks_till_true(self):
         self._mocks_for_block_until_auto_reconnect_model(True, True)

unit_tests/utilities/test_zaza_utilities_generic.py

@@ -243,7 +243,7 @@ def test_series_upgrade(self):
             _unit, _machine_num, origin=_origin,
             to_series=_to_series, from_series=_from_series,
             workaround_script=_workaround_script, files=_files)
-        self.block_until_all_units_idle.called_with()
+        self.block_until_all_units_idle.assert_called_with()
         self.prepare_series_upgrade.assert_called_once_with(
             _machine_num, to_series=_to_series)
         self.wrap_do_release_upgrade.assert_called_once_with(