Implemented/fixed/ported loading of blend files and getting blocks & props

tests/test_blendfile_loading.py

@@ -0,0 +1,45 @@
+import pathlib
+import unittest
+
+import os
+
+from blender_asset_tracer import blendfile
+
+
+class BlendLoadingTest(unittest.TestCase):
+    @classmethod
+    def setUpClass(cls):
+        cls.blendfiles = pathlib.Path(__file__).with_name('blendfiles')
+
+    def setUp(self):
+        self.bf = None
+
+    def tearDown(self):
+        if self.bf:
+            self.bf.close()
+
+    def test_some_properties(self):
+        self.bf = blendfile.BlendFile(self.blendfiles / 'basic_file.blend')
+        self.assertFalse(self.bf.is_compressed)
+        self.assertEqual(1, len(self.bf.code_index[b'OB']))
+        ob = self.bf.code_index[b'OB'][0]
+        self.assertEqual('Object', ob.dna_type_name)
+
+        # Try low level operation to read a property.
+        self.bf.fileobj.seek(ob.file_offset, os.SEEK_SET)
+        loc = ob.dna_type.field_get(self.bf.header, self.bf.fileobj, b'loc')
+        self.assertEqual(loc, [2.0, 3.0, 5.0])
+
+        # Try high level operation to read the same property.
+        loc = ob.get(b'loc')
+        self.assertEqual(loc, [2.0, 3.0, 5.0])
+
+        # Try getting a subproperty.
+        name = ob.get((b'id', b'name'))
+        self.assertEqual('OBümlaut', name)
+
+        # Try following a pointer.
+        mesh_ptr = ob.get(b'data')
+        mesh = self.bf.block_from_offset[mesh_ptr]
+        mname = mesh.get((b'id', b'name'))
+        self.assertEqual('MECube³', mname)