Bug 1053069 - Make mozbuild.util.ReadOnlyDefaultDict raise an exception on update() and del. r=gps

python/mozbuild/mozbuild/test/common.py

@@ -27,9 +27,7 @@ class MockConfig(object):
             'MOZ_BAR': 'bar',
             'MOZ_TRUE': '1',
             'MOZ_FALSE': '',
-        })
-
-        self.substs.update(extra_substs)
+        }, **extra_substs)
 
         self.substs_unicode = ReadOnlyDict({k.decode('utf-8'): v.decode('utf-8',
             'replace') for k, v in self.substs.items()})

python/mozbuild/mozbuild/test/frontend/test_emitter.py

@@ -220,7 +220,7 @@ class TestEmitterBasic(unittest.TestCase):
         reader = self.reader('resources')
         objs = self.read_topsrcdir(reader)
 
-        expected_defines = reader.config.defines
+        expected_defines = dict(reader.config.defines)
         expected_defines.update({
             'FOO': True,
             'BAR': 'BAZ',

python/mozbuild/mozbuild/test/test_containers.py

@@ -27,6 +27,26 @@ class TestReadOnlyDict(unittest.TestCase):
         with self.assertRaises(Exception):
             test['baz'] = True
 
+    def test_update(self):
+        original = {'foo': 1, 'bar': 2}
+
+        test = ReadOnlyDict(original)
+
+        with self.assertRaises(Exception):
+            test.update(foo=2)
+
+        self.assertEqual(original, test)
+
+    def test_del(self):
+        original = {'foo': 1, 'bar': 2}
+
+        test = ReadOnlyDict(original)
+
+        with self.assertRaises(Exception):
+            del test['foo']
+
+        self.assertEqual(original, test)
+
 
 class TestReadOnlyDefaultDict(unittest.TestCase):
     def test_simple(self):

python/mozbuild/mozbuild/util.py

@@ -53,9 +53,15 @@ class ReadOnlyDict(dict):
     def __init__(self, *args, **kwargs):
         dict.__init__(self, *args, **kwargs)
 
-    def __setitem__(self, name, value):
+    def __delitem__(self, key):
+        raise Exception('Object does not support deletion.')
+
+    def __setitem__(self, key, value):
         raise Exception('Object does not support assignment.')
 
+    def update(self, *args, **kwargs):
+        raise Exception('Object does not support update.')
+
 
 class undefined_default(object):
     """Represents an undefined argument value that isn't None."""