Alembic import: added simple unit test for importer.

It only tests the presence of the objects and their parent/child pointers.
Matrix and animated properties should be done in a later test.

tests/python/CMakeLists.txt

@@ -444,6 +444,12 @@ if(WITH_CYCLES)
 endif()
 
 if(WITH_ALEMBIC)
+	add_test(script_alembic_import ${TEST_BLENDER_EXE}
+		--python ${CMAKE_CURRENT_LIST_DIR}/bl_alembic_import_test.py
+		--
+		--testdir "${TEST_SRC_DIR}/alembic"
+	)
+
 	if(MSVC)
 		add_test(NAME cycles_${subject}_test
 			COMMAND

tests/python/bl_alembic_import_test.py

@@ -0,0 +1,92 @@
+# ##### BEGIN GPL LICENSE BLOCK #####
+#
+#  This program is free software; you can redistribute it and/or
+#  modify it under the terms of the GNU General Public License
+#  as published by the Free Software Foundation; either version 2
+#  of the License, or (at your option) any later version.
+#
+#  This program is distributed in the hope that it will be useful,
+#  but WITHOUT ANY WARRANTY; without even the implied warranty of
+#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#  GNU General Public License for more details.
+#
+#  You should have received a copy of the GNU General Public License
+#  along with this program; if not, write to the Free Software Foundation,
+#  Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+#
+# ##### END GPL LICENSE BLOCK #####
+
+# <pep8 compliant>
+
+"""
+./blender.bin --background -noaudio --factory-startup --python tests/python/bl_alembic_import_test.py -- --testdir /path/to/lib/tests/alembic
+"""
+
+import pathlib
+import sys
+import unittest
+
+import bpy
+
+args = None
+
+
+class SimpleImportTest(unittest.TestCase):
+    @classmethod
+    def setUpClass(cls):
+        cls.testdir = args.testdir
+
+    def setUp(self):
+        self.assertTrue(self.testdir.exists(),
+                        'Test dir %s should exist' % self.testdir)
+
+        # Make sure we always start with a known-empty file.
+        bpy.ops.wm.open_mainfile(filepath=str(self.testdir / "empty.blend"))
+
+    def test_import_cube_hierarchy(self):
+        res = bpy.ops.wm.alembic_import(
+            filepath=str(self.testdir / "cubes-hierarchy.abc"),
+            as_background_job=False)
+        self.assertEqual({'FINISHED'}, res)
+
+        # The objects should be linked to scene_collection in Blender 2.8,
+        # and to scene in Blender 2.7x.
+        objects = bpy.context.scene.objects
+        self.assertEqual(13, len(objects))
+
+        # Test the hierarchy.
+        self.assertIsNone(objects['Cube'].parent)
+        self.assertEqual(objects['Cube'], objects['Cube_001'].parent)
+        self.assertEqual(objects['Cube'], objects['Cube_002'].parent)
+        self.assertEqual(objects['Cube'], objects['Cube_003'].parent)
+        self.assertEqual(objects['Cube_003'], objects['Cube_004'].parent)
+        self.assertEqual(objects['Cube_003'], objects['Cube_005'].parent)
+        self.assertEqual(objects['Cube_003'], objects['Cube_006'].parent)
+
+
+def main():
+    global args
+    import argparse
+
+    if '--' in sys.argv:
+        argv = [sys.argv[0]] + sys.argv[sys.argv.index('--')+1:]
+    else:
+        argv = sys.argv
+
+    parser = argparse.ArgumentParser()
+    parser.add_argument('--testdir', required=True, type=pathlib.Path)
+    args, remaining = parser.parse_known_args(argv)
+
+    unittest.main(argv=remaining)
+
+
+if __name__ == "__main__":
+    import traceback
+    # So a python error exits Blender itself too
+    try:
+        main()
+    except SystemExit:
+        raise
+    except:
+        traceback.print_exc()
+        sys.exit(1)