Beginning of CLI interface + protection against infinite recursion.

tests/test_tracer_file_sequence.py

@@ -0,0 +1,39 @@
+from abstract_test import AbstractBlendFileTest
+
+from blender_asset_tracer.tracer import file_sequence
+
+
+class ExpandFileSequenceTest(AbstractBlendFileTest):
+    def setUp(self):
+        super().setUp()
+        self.imgseq = [self.blendfiles / ('imgseq/%06d.png' % num)
+                       for num in range(210, 215)]
+
+    def test_glob(self):
+        path = self.blendfiles / 'imgseq/*.png'
+        actual = list(file_sequence.expand_sequence(path))
+        self.assertEqual(self.imgseq, actual)
+
+    def test_directory(self):
+        path = self.blendfiles / 'imgseq'
+        actual = list(file_sequence.expand_sequence(path))
+        expected = self.imgseq + [self.blendfiles / 'imgseq/LICENSE.txt']
+        self.assertEqual(expected, actual)
+
+    def test_first_file(self):
+        path = self.blendfiles / 'imgseq/000210.png'
+        actual = list(file_sequence.expand_sequence(path))
+        self.assertEqual(self.imgseq, actual)
+
+    def test_nonexistent(self):
+        path = self.blendfiles / 'nonexistant'
+        with self.assertRaises(file_sequence.DoesNotExist) as raises:
+            for result in file_sequence.expand_sequence(path):
+                self.fail('unexpected result %r' % result)
+
+        self.assertEqual(path, raises.exception.path)
+
+    def test_non_sequence_file(self):
+        path = self.blendfiles / 'imgseq/LICENSE.txt'
+        actual = list(file_sequence.expand_sequence(path))
+        self.assertEqual([path], actual)