Work around some coupling of links, net & volume_from

This is minimal disruptive change I could make to ensure
the service integration tests worked, now we have some validation
happening.

There is some coupling/entanglement/assumption going on here.

Project when creating a service, using it's class method from_dicts
performs some transformations on links, net & volume_from, which
get passed on to Service when creating. Service itself, then performs
some transformation on those values. This worked fine in the tests before
because those options were merely passed on via make_service_dict.

This is no longer true with our validation in place. You can't pass to
ServiceLoader [(obj, 'string')] for links, the validation expects it to be
a list of strings. Which it would be when passed into Project.from_dicts
method.

I think the tests need some re-factoring but for now, manually deleting
keys out of the kwargs and then putting them back in for Service Creation
allows the tests to continue.

I am not super happy about this approach. Hopefully we can come back and
improve it.

Signed-off-by: Mazz Mosley <mazz@houseofmnowster.com>

tests/integration/testcases.py

@@ -31,11 +31,29 @@ class DockerClientTestCase(unittest.TestCase):
         if 'command' not in kwargs:
             kwargs['command'] = ["top"]
 
+        links = kwargs.get('links', None)
+        volumes_from = kwargs.get('volumes_from', None)
+        net = kwargs.get('net', None)
+
+        workaround_options = ['links', 'volumes_from', 'net']
+        for key in workaround_options:
+            try:
+                del kwargs[key]
+            except KeyError:
+                pass
+
         options = ServiceLoader(working_dir='.', filename=None, service_name=name, service_dict=kwargs).make_service_dict()
 
         labels = options.setdefault('labels', {})
         labels['com.docker.compose.test-name'] = self.id()
 
+        if links:
+            options['links'] = links
+        if volumes_from:
+            options['volumes_from'] = volumes_from
+        if net:
+            options['net'] = net
+
         return Service(
             project='composetest',
             client=self.client,