Warn and default to null if repo or ref are given

This now means that the system morphology is not altered when chunks are
altered, so some tests had to change.

Since this uses the python warnings API, these warnings can be ignored
by running

    python -W ignore:"stratum morphology" \
           -W ignore:"system morphology" \
           "$(which morph)" ...`

or turned into errors with

    python -W error:"stratum morphology" \
           -W error:"system morphology" \
           "$(which morph)" ...`

1 files changed, 77 insertions, 3 deletions

diff --git a/morphlib/morphloader_tests.py b/morphlib/morphloader_tests.py
index bd3e77e3..b8738804 100644
--- a/morphlib/morphloader_tests.py
+++ b/morphlib/morphloader_tests.py
@@ -16,12 +16,15 @@
 # =*= License: GPL-2 =*=
 
 
+import contextlib
 import os
 import shutil
 import tempfile
 import unittest
+import warnings
 
 import morphlib
+from morphlib.morphloader import MorphologyObsoleteFieldWarning
 
 
 class MorphologyLoaderTests(unittest.TestCase):
@@ -648,10 +651,13 @@ name: foo
             name='foo',
             arch='testarch',
             strata=[
-                {'morph': 'bar'},
+                {
+                    'morph': 'bar',
+                    'repo': 'obsolete',
+                    'ref': 'obsolete',
+                },
             ])
         self.loader.set_defaults(m)
-        self.loader.validate(m)
         self.assertEqual(
             {
                 'kind': 'system',
@@ -675,7 +681,11 @@ name: foo
                 'name': 'foo',
                 'arch': 'testarch',
                 'strata': [
-                    {'morph': 'bar'},
+                    {
+                        'morph': 'bar',
+                        'repo': None,
+                        'ref': None,
+                    },
                 ],
                 'configuration-extensions': [],
             })
@@ -788,3 +798,67 @@ name: foo
         self.assertEqual(m['name'], 'foo')
         self.assertEqual(m['kind'], 'cluster')
         self.assertEqual(m['systems'][0]['morph'], 'bar')
+
+    @contextlib.contextmanager
+    def catch_warnings(*warning_classes):
+        with warnings.catch_warnings(record=True) as caught_warnings:
+            warnings.resetwarnings()
+            for warning_class in warning_classes:
+                warnings.simplefilter("always", warning_class)
+            yield caught_warnings
+
+    def test_warns_when_systems_refer_to_strata_with_repo_or_ref(self):
+        for obsolete_field in ('repo', 'ref'):
+            m = morphlib.morph3.Morphology(
+                name="foo",
+                kind="system",
+                arch="testarch",
+                strata=[
+                    {
+                        'morph': 'bar',
+                        obsolete_field: 'obsolete',
+                    }])
+
+            with self.catch_warnings(MorphologyObsoleteFieldWarning) \
+            as caught_warnings:
+
+                self.loader.validate(m)
+                self.assertEqual(len(caught_warnings), 1)
+                warning = caught_warnings[0].message
+                self.assertEqual(warning.kind, 'system')
+                self.assertEqual(warning.morphology_name, 'foo')
+                self.assertEqual(warning.stratum_name, 'bar')
+                self.assertEqual(warning.field, obsolete_field)
+
+    def test_warns_when_strata_refer_to_build_depends_with_repo_or_ref(self):
+        for obsolete_field in ('repo', 'ref'):
+            m = morphlib.morph3.Morphology(
+                {
+                    'name': 'foo',
+                    'kind': 'stratum',
+                    'build-depends': [
+                        {
+                            'morph': 'bar',
+                            obsolete_field: 'obsolete'
+                        },
+                    ],
+                    'chunks': [
+                        {
+                            'morph': 'chunk',
+                            'name': 'chunk',
+                            'build-mode': 'test',
+                            'build-depends': [],
+                        },
+                    ],
+                })
+
+            with self.catch_warnings(MorphologyObsoleteFieldWarning) \
+            as caught_warnings:
+
+                self.loader.validate(m)
+                self.assertEqual(len(caught_warnings), 1)
+                warning = caught_warnings[0].message
+                self.assertEqual(warning.kind, 'stratum')
+                self.assertEqual(warning.morphology_name, 'foo')
+                self.assertEqual(warning.stratum_name, 'bar')
+                self.assertEqual(warning.field, obsolete_field)