Add client capabilities, enable messages

The API version the client sends can now be used to check what the client
expects or is capable of.

All version tests IPA does will be be named and listed in one module,
ipalib.capabilities, which includes a function to test a specific capability
against an API version.
Similarly to Python's __future__ module, capabilities.py also serves as
documentation of backwards-incompatible changes to the API.

The first capability to be defined is "messages". Recent enough clients can
accept a list of warnings or other info under the "messages" key in the
result dict.

If a JSON client does not send the API version, it is assumed this is a testing
client (e.g. curl from the command line). Such a client "has" all capabilities,
but it will always receive a warning mentioning that forward compatibility
is not guaranteed.
If a XML client does not send the API version, it is assumed it uses the API
version before capabilities were introduced. (This is to keep backwards
compatibility with clients containing bug https://fedorahosted.org/freeipa/ticket/3294)

Whenever a capability is added, the API version must be incremented.
To ensure that, capabilities are written to API.txt and checked by
`makeapi --validate`.

Design page: http://freeipa.org/page/V3/Messages
Ticket: https://fedorahosted.org/freeipa/ticket/2732

1 files changed, 42 insertions, 1 deletions

diff --git a/tests/test_ipalib/test_frontend.py b/tests/test_ipalib/test_frontend.py
index 4b4735599..3a540608d 100644
--- a/tests/test_ipalib/test_frontend.py
+++ b/tests/test_ipalib/test_frontend.py
@@ -27,7 +27,7 @@ from tests.util import assert_equal
 from ipalib.constants import TYPE_ERROR
 from ipalib.base import NameSpace
 from ipalib import frontend, backend, plugable, errors, parameters, config
-from ipalib import output
+from ipalib import output, messages
 from ipalib.parameters import Str
 from ipapython.version import API_VERSION
 
@@ -619,6 +619,47 @@ class test_Command(ClassChecker):
         assert o.run.im_func is self.cls.run.im_func
         assert ('forward', args, kw) == o.run(*args, **kw)
 
+    def test_messages(self):
+        """
+        Test correct handling of messages
+        """
+        class TestMessage(messages.PublicMessage):
+            type = 'info'
+            format = 'This is a message.'
+            errno = 1234
+
+        class my_cmd(self.cls):
+            def execute(self, *args, **kw):
+                result = {'name': 'execute'}
+                messages.add_message(kw['version'], result, TestMessage())
+                return result
+
+            def forward(self, *args, **kw):
+                result = {'name': 'forward'}
+                messages.add_message(kw['version'], result, TestMessage())
+                return result
+
+        args = ('Hello,', 'world,')
+        kw = dict(how_are='you', on_this='fine day?', version=API_VERSION)
+
+        expected = [TestMessage().to_dict()]
+
+        # Test in server context:
+        (api, home) = create_test_api(in_server=True)
+        api.finalize()
+        o = my_cmd()
+        o.set_api(api)
+        assert o.run.im_func is self.cls.run.im_func
+        assert {'name': 'execute', 'messages': expected} == o.run(*args, **kw)
+
+        # Test in non-server context
+        (api, home) = create_test_api(in_server=False)
+        api.finalize()
+        o = my_cmd()
+        o.set_api(api)
+        assert o.run.im_func is self.cls.run.im_func
+        assert {'name': 'forward', 'messages': expected} == o.run(*args, **kw)
+
     def test_validate_output_basic(self):
         """
         Test the `ipalib.frontend.Command.validate_output` method.