Add spec for bp/nova-api-test-inheritance

This patch adds a spec file for the nova-api-test-inheritance blueprint.

Partially implements blueprint nova-api-test-inheritance

Change-Id: I7d7af649c050fa0d427779a370dba097aeab939c

specs/nova-api-test-inheritance.rst

@@ -0,0 +1,127 @@
+::
+
+ This work is licensed under a Creative Commons Attribution 3.0 Unported
+ License.
+
+ http://creativecommons.org/licenses/by/3.0/legalcode
+
+..
+
+====================================
+Improve Nova API test serviceability
+====================================
+
+https://blueprints.launchpad.net/tempest/+spec/nova-api-test-inheritance
+
+Improve Nova API test serviceability by sharing Nova v2/v3 API test code.
+
+
+Problem description
+===================
+
+Now there is a lot of copy&paste test code for Nova v2/v3 API tests.
+In addition, we need to add many checks for API test coverage.
+As the result, we should apply the same changes to v2 and v3 tests and
+that becomes much maintenance burden now.
+
+
+Proposed change
+===============
+
+To improve the maintenancebility, this blueprint proposes the changes to share
+v2 and v3 API test code. The proposed way is the following three steps.
+
+1. Create common base test class
+2. Make each v2 test class inherit the v3 test class
+3. Change the Nova API test directory structure
+
+1. Create common base test class
+--------------------------------
+
+Now each Nova API test class inherits like:
+
+* [v2 test class] -> [BaseV2ComputeTest] -> [BaseComputeTest]
+* [v3 test class] -> [BaseV3ComputeTest] -> [BaseComputeTest]
+
+To share API test classes, we need to create common base test class instead
+of BaseV2ComputeTest/BaseV3ComputeTest. The class instance can switch its
+behavior based on some variable which represents an API version.
+After applying this common class to every API test classes, the existing
+BaseV2ComputeTest and BaseV3ComputeTest can be removed.
+
+2. Make each v2 test class inherit the v3 test class
+----------------------------------------------------
+
+We need to change v3 test classes' inheritances to the common base test class
+and change v2 test classes' inheritances to v3 test class:
+
+* [v2 test class] -> [v3 test class] -> [CommonComputeTest]
+
+In v2 test class, the variable which represents an API version should be "2",
+and the variable should be "3" in v3 test class::
+
+  class SomeApiV3Test(CommonComputeTest):
+    _api_version = 3
+    [..]
+
+  class SomeApiV2Test(SomeApiV3Test):
+    _api_version = 2
+    [..]
+
+3. Change the Nova API test directory structure
+-----------------------------------------------
+
+Current test directory structure is
+
+* tempest/api/compute/    : v2 API test files
+* tempest/api/compute/v3/ : v3 API test files
+
+This structure is not understandable, and it is better to move v2 API test
+files to some directory which shows v2's one clearly.
+
+This blueprint proposes to change the structure to
+
+* tempest/api/compute/    : common test files
+* tempest/api/compute/v2/ : v2 API specific test files
+* tempest/api/compute/v3/ : v3 API specific test files
+
+The test files which can be inherited with the way(2) will be stored to
+"tempest/api/compute/". Otherwise, the hierarchy would be
+
+* [v2 test class] -> [CommonComputeTest]
+* [v3 test class] -> [CommonComputeTest]
+
+and these test files would be stored to
+
+* tempest/api/compute/v2/
+* tempest/api/compute/v3/
+
+
+Implementation
+==============
+
+Assignee(s)
+-----------
+
+Primary assignee:
+  Ken'ichi Ohmichi <oomichi@mxs.nes.nec.co.jp>
+
+Other contributors:
+  Ghanshyam Mann <ghanshyam.mann@nectechnologies.in>
+
+Milestones
+----------
+
+Target Milestone for completion:
+  Juno-2
+
+Work Items
+----------
+
+- Add a common class for Nova v2/v3 API tests
+- Add a common admin class for Nova v2/v3 API tests
+- Share API test clases
+  This work needs a lot of patchset.
+  To manage the task progress, I prepare the etherpad:
+  https://etherpad.openstack.org/p/nova-api-test-inheritance
+