Compute: Fix DisplayCommandBase comments for cliff Lister subclass tests

As bug #1477199 describes, the wrong comment below is all over the
unit test code of OSC.

    # DisplayCommandBase.take_action() returns two tuples

There is no such class named DisplayCommandBase in OSC. It is in cliff.

All OSC command classes inherit from the base classes in cliff,
class Command, class Lister and class ShowOne. It is like this:

Object
|--> Command
     |--> DisplayCommandBase
         |--> Lister
         |--> ShowOne

take_action() is an abstract method of class Command, and generally is
overwritten by subclasses.

* Command.take_action() returns nothing.
* Lister.take_action() returns a tuple which contains a tuple of
  columns and a generator used to generate the data.
* ShowOne.take_action() returns an iterator which contains a tuple
  of columns and a tuple of data

So, this problem should be fixed in 3 steps:
1. Remove all DisplayCommandBase comments for tests of classes
   inheriting from class Command in cliff as it returns nothing.
2. Fix all DisplayCommandBase comments for tests of classes
   inheriting from class Lister in cliff. Lister.take_action()
   returns a tuple and a generator.
3. Fix all DisplayCommandBase comments for tests of classes
   inheriting from class ShowOne in cliff. ShowOne.take_action()
   returns two tuples.

This patch finishes step 2 in compute tests.

Change-Id: Idc54ad21eaa1371ebd601327b8d962c7039f2de0
Partial-bug: #1477199

Author: Tang Chen

openstackclient/tests/compute/v2/test_flavor.py

@@ -126,7 +126,9 @@ def test_flavor_list_no_options(self):
 
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstractmethod take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
 
         # Set expected values
@@ -153,7 +155,9 @@ def test_flavor_list_all_flavors(self):
 
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstractmethod take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
 
         # Set expected values
@@ -180,7 +184,9 @@ def test_flavor_list_private_flavors(self):
 
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstractmethod take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
 
         # Set expected values
@@ -207,7 +213,9 @@ def test_flavor_list_public_flavors(self):
 
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstractmethod take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
 
         # Set expected values
@@ -234,7 +242,9 @@ def test_flavor_list_long(self):
 
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstractmethod take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
 
         # Set expected values

openstackclient/tests/compute/v2/test_security_group.py

@@ -158,7 +158,9 @@ def test_security_group_list_no_options(self):
 
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstractmethod take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
 
         # Set expected values

openstackclient/tests/compute/v2/test_security_group_rule.py

@@ -404,7 +404,9 @@ def test_security_group_rule_list(self):
 
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstractmethod take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
 
         collist = (
@@ -440,7 +442,9 @@ def test_security_group_rule_list_no_group(self):
 
         parsed_args = self.check_parser(self.cmd, [], [])
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstractmethod take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
 
         collist = (

openstackclient/tests/compute/v2/test_service.py

@@ -81,7 +81,9 @@ def test_service_list(self):
         ]
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstractmethod take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         self.cmd.take_action(parsed_args)
 
         self.service_mock.list.assert_called_with(