Nova Hyper-V driver refactoring

Blueprint: hyper-v-testing-serialization-improvements

This patchset contains a major refactoring of the Hyper-V driver.

The main reason for this refactoring is to provide proper component
abstraction and decoupling, thus replacing almost entirely the remaining
pre-Essex code previously available. This leads to a considerable
semplification of the testing framework, which is now entirely based on
stubs and mocks (mox), without any serialized stub / mock.

From an architectural perspective, the main driver class delegates
operations to "ops" classes (e.g. VMOps, VolumeOps, etc) which contain the
main logic and delegate OS specific actions to "utils" classes (e.g. VMUtils,
LiveMigrationUtils, etc) where the WMI and Win32 API OS specific code resides.

Additional attention has been put also into a better PEP8 code formatting,
including compliance with not mandatory checks like E121 through E128.

Change-Id: I900719c02b7c6b48d44ca68903813a1dcd023f9f

nova/tests/hyperv/README.rst

@@ -1,83 +0,0 @@
-=====================================
-OpenStack Hyper-V Nova Testing Architecture
-=====================================
-
-The Hyper-V Nova Compute plugin uses Windows Management Instrumentation (WMI)
-as the main API for hypervisor related operations.
-WMI has a database / procedural oriented nature that can become difficult to
-test with a traditional static mock / stub based unit testing approach.
-
-The included Hyper-V testing framework has been developed with the
-following goals:
-
-1) Dynamic mock generation.
-2) Decoupling. No dependencies on WMI or any other module.
-    The tests are designed to work with mocked objects in all cases, including
-    OS-dependent (e.g. wmi, os, subprocess) and non-deterministic
-    (e.g. time, uuid) modules
-3) Transparency. Mocks and real objects can be swapped via DI
-    or monkey patching.
-4) Platform independence.
-5) Tests need to be executed against the real object or against the mocks
-    with a simple configuration switch. Development efforts can highly
-    benefit from this feature.
-6) It must be possible to change a mock's behavior without running the tests
-    against the hypervisor (e.g. by manually adding a value / return value).
-
-The tests included in this package include dynamically generated mock objects,
-based on the recording of the attribute values and invocations on the
-real WMI objects and other OS dependent features.
-The generated mock objects are serialized in the nova/tests/hyperv/stubs
-directory as gzipped pickled objects.
-
-An environment variable controls the execution mode of the tests.
-
-Recording mode:
-
-NOVA_GENERATE_TEST_MOCKS=True
-Tests are executed on the hypervisor (without mocks), and mock objects are
-generated.
-
-Replay mode:
-
-NOVA_GENERATE_TEST_MOCKS=
-Tests are executed with the existing mock objects (default).
-
-Mock generation is performed by nova.tests.hyperv.mockproxy.MockProxy.
-Instances of this class wrap objects that need to be mocked and act as a
-delegate on the wrapped object by leveraging Python's __getattr__ feature.
-Attribute values and method call return values are recorded at each access.
-Objects returned by attributes and method invocations are wrapped in a
-MockProxy consistently.
-From a caller perspective, the MockProxy is completely transparent,
-with the exception of calls to the type(...) builtin function.
-
-At the end of the test, a mock is generated by each MockProxy by calling
-the get_mock() method. A mock is represented by an instance of the
-nova.tests.hyperv.mockproxy.Mock class.
-
-The Mock class task consists of replicating the behaviour of the mocked
-objects / modules by returning the same values in the same order, for example:
-
-def check_path(path):
-    if not os.path.exists(path):
-        os.makedirs(path)
-
-check_path(path)
-# The second time os.path.exists returns True
-check_path(path)
-
-The injection of MockProxy / Mock instances is performed by the
-nova.tests.hyperv.basetestcase.BaseTestCase class in the setUp()
-method via selective monkey patching.
-Mocks are serialized in tearDown() during recording.
-
-The actual Hyper-V test case inherits from BaseTestCase:
-nova.tests.hyperv.test_hypervapi.HyperVAPITestCase
-
-
-Future directions:
-
-1) Replace the pickled files with a more generic serialization option (e.g. json)
-2) Add methods to statically extend the mocks (e.g. method call return values)
-3) Extend an existing framework, e.g. mox

nova/tests/hyperv/stubs/README.rst

@@ -1,2 +0,0 @@
-Files with extension p.gz are compressed pickle files containing serialized
-mocks used during unit testing