Bug 971272 - Part 2: Expose FileRegistry.required_directories. r=gps

python/mozbuild/mozpack/copier.py

@@ -134,6 +134,15 @@ class FileRegistry(object):
         '''
         return self._files.iteritems()
 
+    def required_directories(self):
+        '''
+        Return the set of directories required by the paths in the container,
+        in no particular order.  The returned directories are relative to an
+        unspecified (virtual) root directory (and do not include said root
+        directory).
+        '''
+        return set(k for k, v in self._required_directories.items() if v > 0)
+
 
 class FileCopyResult(object):
     """Represents results of a FileCopier.copy operation."""

python/mozbuild/mozpack/test/test_copier.py

@@ -116,6 +116,33 @@ class TestFileRegistry(MatchTestTemplate, unittest.TestCase):
         self.registry.remove('bar/zot')
         self.registry.add('bar/zot', GeneratedFile('barzot'))
 
+    def test_required_directories(self):
+        self.registry = FileRegistry()
+
+        self.registry.add('foo', GeneratedFile('foo'))
+        self.assertEqual(self.registry.required_directories(), set())
+
+        self.registry.add('bar/baz', GeneratedFile('barbaz'))
+        self.assertEqual(self.registry.required_directories(), {'bar'})
+
+        self.registry.add('bar/zot', GeneratedFile('barzot'))
+        self.assertEqual(self.registry.required_directories(), {'bar'})
+
+        self.registry.add('bar/zap/zot', GeneratedFile('barzapzot'))
+        self.assertEqual(self.registry.required_directories(), {'bar', 'bar/zap'})
+
+        self.registry.remove('bar/zap/zot')
+        self.assertEqual(self.registry.required_directories(), {'bar'})
+
+        self.registry.remove('bar/baz')
+        self.assertEqual(self.registry.required_directories(), {'bar'})
+
+        self.registry.remove('bar/zot')
+        self.assertEqual(self.registry.required_directories(), set())
+
+        self.registry.add('x/y/z', GeneratedFile('xyz'))
+        self.assertEqual(self.registry.required_directories(), {'x', 'x/y'})
+
 
 class TestFileCopier(TestWithTmpDir):
     def all_dirs(self, base):