Merge "Add tempest test writing guide"

doc/source/configuration.rst

@@ -9,6 +9,8 @@ they are used in conjunction. The source of truth on each option is the sample
 config file which explains the purpose of each individual option. You can see
 the sample config file here: :ref:`tempest-sampleconf`
 
+.. _tempest_cred_provider_conf:
+
 Test Credentials
 ----------------
 
@@ -232,6 +234,9 @@ Tempest's config around network configuration.
 
 Enabling Remote Access to Created Servers
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. _tempest_conf_network_allocation:
+
 Network Creation/Usage for Servers
 """"""""""""""""""""""""""""""""""
 When Tempest creates servers for testing, some tests require being able to

doc/source/index.rst

@@ -68,6 +68,7 @@ Development
    REVIEWING
    microversion_testing
    test-removal
+   write_tests
 
 -------
 Plugins

doc/source/plugin.rst

@@ -1,3 +1,5 @@
+.. _tempest_plugin:
+
 =============================
 Tempest Test Plugin Interface
 =============================

doc/source/write_tests.rst

@@ -0,0 +1,243 @@
+.. _tempest_test_writing:
+
+Tempest Test Writing Guide
+==========================
+
+This guide serves as a starting point for developers working on writing new
+Tempest tests. At a high level tests in Tempest are just tests that conform to
+the standard python `unit test`_ framework. But there are several aspects of
+that are unique to tempest and it's role as an integration test suite running
+against a real cloud.
+
+.. _unit test: https://docs.python.org/3.6/library/unittest.html
+
+.. note:: This guide is for writing tests in the tempest repository. While many
+          parts of this guide are also applicable to tempest plugins, not all
+          the APIs mentioned are considered stable or recommended for use in
+          plugins. Please refer to :ref:`tempest_plugin` for details about
+          writing plugins
+
+
+Adding a New TestCase
+=====================
+
+The base unit of testing in Tempest is the `TestCase`_ (also called the test
+class). Each TestCase contains test methods which are the individual tests that
+will be executed by the test runner. But, the TestCase is the smallest self
+contained unit for tests from the tempest perspective. It's also the level at
+which tempest is parallel safe. In other words, multiple TestCases can be
+executed in parallel, but individual test methods in the same TestCase can not.
+Also, all test methods within a TestCase are assumed to be executed serially. As
+such you can use the test case to store variables that are shared between
+methods.
+
+.. _TestCase: https://docs.python.org/3.6/library/unittest.html#unittest.TestCase
+
+In standard unittest the lifecycle of a TestCase can be described in the
+following phases:
+
+ #. setUpClass
+ #. setUp
+ #. Test Execution
+ #. tearDown
+ #. doCleanups
+ #. tearDownClass
+
+setUpClass
+----------
+
+The setUpClass phase is the first phase executed by the test runner and is used
+to perform any setup required for all the test methods to be executed. In
+Tempest this is a very important step and will automatically do the necessary
+setup for interacting with the configured cloud.
+
+To accomplish this you do **not** define a setUpClass function, instead there
+are a number of predefined phases to setUpClass that are used. The phases are:
+
+ * skip_checks
+ * setup_credentials
+ * setup_clients
+ * resource_setup
+
+which is executed in that order. An example of a TestCase which defines all
+of these would be::
+
+  from tempest import config
+  from tempest import test
+
+  CONF = config.CONF
+
+
+  class TestExampleCase(test.BaseTestCase):
+
+    @classmethod
+    def skip_checks(cls):
+        """This section is used to evaluate config early and skip all test
+           methods based on these checks
+        """
+        super(TestExampleCase, cls).skip_checks()
+        if not CONF.section.foo
+            cls.skip('A helpful message')
+
+    @classmethod
+    def setup_credentials(cls):
+        """This section is used to do any manual credential allocation and also
+           in the case of dynamic credentials to override the default network
+           resource creation/auto allocation
+        """
+        # This call is used to tell the credential allocator to not create any
+        # network resources for this test case. It also enables selective
+        # creation of other neutron resources. NOTE: it must go before the
+        # super call
+        cls.set_network_resources()
+        super(TestExampleCase, cls).setup_credentials()
+
+    @classmethod
+    def setup_clients(cls):
+        """This section is used to setup client aliases from the manager object
+           or to initialize any additional clients. Except in a few very
+           specific situations you should not need to use this.
+        """
+        super(TestExampleCase, cls).setup_clients()
+        cls.servers_client = cls.os.servers_client
+
+    @classmethod
+    def resource_setup(cls):
+        """This section is used to create any resources or objects which are
+           going to be used and shared by **all** test methods in the
+           TestCase. Note then anything created in this section must also be
+           destroyed in the corresponding resource_cleanup() method (which will
+           be run during tearDownClass())
+        """
+        super(TestExampleCase, cls).resource_setup()
+        cls.shared_server = cls.servers_client.create_server(...)
+
+
+Allocating Credentials
+''''''''''''''''''''''
+
+Since Tempest tests are all about testing a running cloud, every test will need
+credentials to be able to make API requests against the cloud. Since this is
+critical to operation and, when running in parallel, easy to make a mistake,
+the base TestCase class will automatically allocate a regular user for each
+TestCase during the setup_credentials() phase. During this process it will also
+initialize a client manager object using those credentials, which will be your
+entry point into interacting with the cloud. For more details on how credentials
+are allocated the :ref:`tempest_cred_provider_conf` section of the Tempest
+Configuration Guide provides more details on the operation of this.
+
+There are some cases when you need more than a single set of credentials, or
+credentials with a more specialized set of roles. To accomplish this you have
+to set a class variable ``credentials`` on the TestCase directly. For example::
+
+    from tempest import test
+
+    class TestExampleAdmin(test.BaseTestCase):
+
+        credentials = ['primary', 'admin']
+
+    @classmethod
+    def skip_checks(cls):
+    ...
+
+In this example the ``TestExampleAdmin`` TestCase will allocate 2 sets of
+credentials, one regular user and one admin user. The corresponding manager
+objects will be set as class variables cls.os and cls.os_adm respectively. You
+can also allocate a second user by putting **'alt'** in the list too. A set of
+alt credentials are the same as primary but can be used for tests cases that
+need a second user/project.
+
+You can also specify credentials with specific roles assigned. This is useful
+for cases where there are specific RBAC requirements hard coded into an API.
+The canonical example of this are swift tests which often want to test swift's
+concepts of operator and reseller_admin. An actual example from tempest on how
+to do this is::
+
+    class PublicObjectTest(base.BaseObjectTest):
+
+        credentials = [['operator', CONF.object_storage.operator_role],
+                       ['operator_alt', CONF.object_storage.operator_role]]
+
+        @classmethod
+        def setup_credentials(cls):
+            super(PublicObjectTest, cls).setup_credentials()
+            ...
+
+In this case the manager objects will be set to ``cls.os_roles_operator`` and
+``cls.os_roles_operator_alt`` respectively.
+
+
+There is no limit to how many credentials you can allocate in this manner,
+however in almost every case you should **not** need more than 3 sets of
+credentials per test case.
+
+To figure out the mapping of manager objects set on the TestCase and the
+requested credentials you can reference:
+
++-------------------+---------------------+
+| Credentials Entry | Manager Variable    |
++===================+=====================+
+| primary           | cls.os              |
++-------------------+---------------------+
+| admin             | cls.os_adm          |
++-------------------+---------------------+
+| alt               | cls.os_alt          |
++-------------------+---------------------+
+| [$label, $role]   | cls.os_roles_$label |
++-------------------+---------------------+
+
+By default cls.os is available since it is allocated in the base tempest test
+class. (located in tempest/test.py) If your TestCase inherits from a different
+direct parent class (it'll still inherit from the BaseTestCase, just not
+directly) be sure to check if that class overrides allocated credentials.
+
+Dealing with Network Allocation
+'''''''''''''''''''''''''''''''
+
+When neutron is enabled and a testing requires networking this isn't normally
+automatically setup when a tenant is created. Since tempest needs isolated
+tenants to function properly it also needs to handle network allocation. By
+default the base test class will allocate a network, subnet, and router
+automatically. (this depends on the configured credential provider, for more
+details see: :ref:`tempest_conf_network_allocation`) However, there are
+situations where you do no need all of these resources allocated. (or your
+TestCase inherits from a class that overrides the default in tempest/test.py)
+There is a class level mechanism to override this allocation and specify which
+resources you need. To do this you need to call `cls.set_network_resources()`
+in the `setup_credentials()` method before the `super()`. For example::
+
+  from tempest import test
+
+
+  class TestExampleCase(test.BaseTestCase):
+
+  @classmethod
+  def setup_credentials(cls):
+      cls.set_network_resources(network=True, subnet=True, router=False)
+      super(TestExampleCase, cls).setup_credentials()
+
+There are 2 quirks with the usage here. First for the set_network_resources
+function to work properly it **must be called before super()**. This is so
+that children classes' settings are always used instead of a parent classes'.
+The other quirk here is that if you do not want to allocate any network
+resources for your test class simply call `set_network_resources()` without
+any arguments. For example::
+
+  from tempest import test
+
+
+  class TestExampleCase(test.BaseTestCase):
+
+  @classmethod
+  def setup_credentials(cls):
+      cls.set_network_resources()
+      super(TestExampleCase, cls).setup_credentials()
+
+This will not allocate any networking resources. This is because by default all
+the arguments default to False.
+
+It's also worth pointing out that it is common for base test classes for
+different services (and scenario tests) to override this setting. When
+inheriting from classes other than the base TestCase in tempest/test.py it is
+worth checking the immediate parent for what is set to determine if your
+class needs to override that setting.