Reorganize unit test locations under tests/unittests (#1126)

This attempts to standardize unit test file location under test/unittests/
such that any source file located at cloudinit/path/to/file.py may have a
corresponding unit test file at test/unittests/path/to/test_file.py.

Noteworthy Comments:
====================
Four different duplicate test files existed:
test_{gpg,util,cc_mounts,cc_resolv_conf}.py
Each of these duplicate file pairs has been merged together. This is a
break in git history for these files.

The test suite appears to have a dependency on test order. Changing test
order causes some tests to fail. This should be rectified, but for now
some tests have been modified in
tests/unittests/config/test_set_passwords.py.

A helper class name starts with "Test" which causes pytest to try
executing it as a test case, which then throws warnings "due to Class
having __init__()".  Silence by changing the name of the class.

# helpers.py is imported in many test files, import paths change
cloudinit/tests/helpers.py -> tests/unittests/helpers.py

# Move directories:
cloudinit/distros/tests -> tests/unittests/distros
cloudinit/cmd/devel/tests -> tests/unittests/cmd/devel
cloudinit/cmd/tests -> tests/unittests/cmd/
cloudinit/sources/helpers/tests -> tests/unittests/sources/helpers
cloudinit/sources/tests -> tests/unittests/sources
cloudinit/net/tests -> tests/unittests/net
cloudinit/config/tests -> tests/unittests/config
cloudinit/analyze/tests/ -> tests/unittests/analyze/

# Standardize tests already in tests/unittests/
test_datasource -> sources
test_distros -> distros
test_vmware -> sources/vmware
test_handler -> config        # this contains cloudconfig module tests
test_runs -> runs

1 files changed, 52 insertions, 0 deletions

diff --git a/tests/unittests/test_upgrade.py b/tests/unittests/test_upgrade.py
new file mode 100644
index 00000000..d7a721a2
--- /dev/null
+++ b/tests/unittests/test_upgrade.py
@@ -0,0 +1,52 @@
+# Copyright (C) 2020 Canonical Ltd.
+#
+# Author: Daniel Watkins <oddbloke@ubuntu.com>
+#
+# This file is part of cloud-init. See LICENSE file for license information.
+
+"""Upgrade testing for cloud-init.
+
+This module tests cloud-init's behaviour across upgrades.  Specifically, it
+specifies a set of invariants that the current codebase expects to be true (as
+tests in ``TestUpgrade``) and then checks that these hold true after unpickling
+``obj.pkl``s from previous versions of cloud-init; those pickles are stored in
+``tests/data/old_pickles/``.
+"""
+
+import operator
+import pathlib
+
+import pytest
+
+from cloudinit.stages import _pkl_load
+from tests.unittests.helpers import resourceLocation
+
+
+class TestUpgrade:
+    @pytest.fixture(
+        params=pathlib.Path(resourceLocation("old_pickles")).glob("*.pkl"),
+        scope="class",
+        ids=operator.attrgetter("name"),
+    )
+    def previous_obj_pkl(self, request):
+        """Load each pickle to memory once, then run all tests against it.
+
+        Test implementations _must not_ modify the ``previous_obj_pkl`` which
+        they are passed, as that will affect tests that run after them.
+        """
+        return _pkl_load(str(request.param))
+
+    def test_networking_set_on_distro(self, previous_obj_pkl):
+        """We always expect to have ``.networking`` on ``Distro`` objects."""
+        assert previous_obj_pkl.distro.networking is not None
+
+    def test_blacklist_drivers_set_on_networking(self, previous_obj_pkl):
+        """We always expect Networking.blacklist_drivers to be initialised."""
+        assert previous_obj_pkl.distro.networking.blacklist_drivers is None
+
+    def test_paths_has_run_dir_attribute(self, previous_obj_pkl):
+        assert previous_obj_pkl.paths.run_dir is not None
+
+    def test_vendordata_exists(self, previous_obj_pkl):
+        assert previous_obj_pkl.vendordata2 is None
+        assert previous_obj_pkl.vendordata2_raw is None