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, 11 insertions, 2 deletions

diff --git a/doc/rtd/topics/testing.rst b/doc/rtd/topics/testing.rst
index d882e036..7a1e3eec 100644
--- a/doc/rtd/topics/testing.rst
+++ b/doc/rtd/topics/testing.rst
@@ -3,8 +3,7 @@ Testing
 *******
 
 cloud-init has both unit tests and integration tests. Unit tests can
-be found in-tree alongside the source code, as well as
-at ``tests/unittests``. Integration tests can be found at
+be found at ``tests/unittests``. Integration tests can be found at
 ``tests/integration_tests``. Documentation specifically for integration
 tests can be found on the :ref:`integration_tests` page, but
 the guidelines specified below apply to both types of tests.
@@ -36,6 +35,16 @@ Test Layout
     subclass (indirectly) from ``TestCase`` (e.g.
     `TestPrependBaseCommands`_)
 
+* Unit tests and integration tests are located under cloud-init/tests
+
+  * For consistency, unit test files should have a matching name and
+    directory location under `tests/unittests`
+
+  * For example: the expected test file for code in
+    `cloudinit/path/to/file.py` is
+    `tests/unittests/path/to/test_file.py`
+
+
 ``pytest`` Tests
 ----------------