From 825981a102422c01b054a93c7de00a680b5ce77f Mon Sep 17 00:00:00 2001
From: Ben Brown <ben.brown@codethink.co.uk>
Date: Wed, 8 Jan 2014 12:10:58 +0000
Subject: Add validation for chunk refs in strata to be (non-empty) strings

---
 morphlib/morphloader.py       | 33 +++++++++++++++++++++++++++++++++
 morphlib/morphloader_tests.py | 36 ++++++++++++++++++++++++++++++++++++
 2 files changed, 69 insertions(+)

diff --git a/morphlib/morphloader.py b/morphlib/morphloader.py
index 637544be..32b5b40b 100644
--- a/morphlib/morphloader.py
+++ b/morphlib/morphloader.py
@@ -120,6 +120,27 @@ class DuplicateChunkError(morphlib.Error):
                   'in stratum %(stratum_name)s' % locals())
 
 
+class EmptyRefError(morphlib.Error):
+
+    def __init__(self, ref_location, morphology):
+        self.ref_location = ref_location
+        self.morphology = morphology
+        morphlib.Error.__init__(
+            self, 'Empty ref found for %(ref_location)s '\
+                  'in %(morphology)s' % locals())
+
+
+class ChunkSpecRefNotStringError(morphlib.Error):
+
+    def __init__(self, ref_value, chunk_name, stratum_name):
+        self.ref_value = ref_value
+        self.chunk_name = chunk_name
+        self.stratum_name = stratum_name
+        morphlib.Error.__init__(
+            self, 'Ref %(ref_value)s for %(chunk_name)s '\
+                  'in stratum %(stratum_name)s is not a string' % locals())
+
+
 class SystemStrataNotListError(morphlib.Error):
 
     def __init__(self, system_name, strata_type):
@@ -130,6 +151,7 @@ class SystemStrataNotListError(morphlib.Error):
             self, 'System %(system_name)s has the wrong type for its strata: '\
                   '%(typename)s, expected list' % locals())
 
+
 class DuplicateStratumError(morphlib.Error):
 
     def __init__(self, system_name, stratum_name):
@@ -366,6 +388,17 @@ class MorphologyLoader(object):
                raise DuplicateChunkError(morph['name'], name)
             names.add(name)
 
+        # All chunk refs must be strings.
+        for spec in morph['chunks']:
+            if 'ref' in spec:
+                ref = spec['ref']
+                if ref == None:
+                    raise EmptyRefError(
+                        spec.get('alias', spec['name']), morph.filename)
+                elif not isinstance(ref, basestring):
+                    raise ChunkSpecRefNotStringError(
+                        ref, spec.get('alias', spec['name']), morph.filename)
+
         # Require build-dependencies for the stratum itself, unless
         # it has chunks built in bootstrap mode.
         if 'build-depends' not in morph:
diff --git a/morphlib/morphloader_tests.py b/morphlib/morphloader_tests.py
index c2fbc5e8..39923348 100644
--- a/morphlib/morphloader_tests.py
+++ b/morphlib/morphloader_tests.py
@@ -187,6 +187,42 @@ build-system: dummy
         self.assertRaises(
             morphlib.morphloader.InvalidFieldError, self.loader.validate, m)
 
+    def test_validate_requires_chunk_refs_in_stratum_to_be_strings(self):
+        m = morphlib.morph3.Morphology({
+            'kind': 'stratum',
+            'name': 'foo',
+            'build-depends': [],
+            'chunks': [
+                {
+                    'name': 'chunk',
+                    'repo': 'test:repo',
+                    'ref': 1,
+                    'build-depends': []
+                }
+            ]
+        })
+        with self.assertRaises(
+                morphlib.morphloader.ChunkSpecRefNotStringError):
+            self.loader.validate(m)
+
+    def test_fails_to_validate_stratum_with_empty_refs_for_a_chunk(self):
+        m = morphlib.morph3.Morphology({
+            'kind': 'stratum',
+            'name': 'foo',
+            'build-depends': [],
+            'chunks' : [
+                {
+                    'name': 'chunk',
+                    'repo': 'test:repo',
+                    'ref': None,
+                    'build-depends': []
+                }
+            ]
+        })
+        with self.assertRaises(
+                morphlib.morphloader.EmptyRefError):
+            self.loader.validate(m)
+
     def test_fails_to_validate_system_with_obsolete_system_kind_field(self):
         m = morphlib.morph3.Morphology({
             'kind': 'system',
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