Start of unit test framework for constraints

Currently this only tests the Child Of constraint. My aim is to cover
constraints with tests before they are refactored/altered.

No functional changes.

2 files changed, 186 insertions, 0 deletions

diff --git a/tests/python/CMakeLists.txt b/tests/python/CMakeLists.txt
index 358200dece4..c47c7a5b4fc 100644
--- a/tests/python/CMakeLists.txt
+++ b/tests/python/CMakeLists.txt
@@ -183,6 +183,13 @@ add_blender_test(
   --run-all-tests
 )
 
+add_blender_test(
+  constraints
+  --python ${CMAKE_CURRENT_LIST_DIR}/bl_constraints.py
+  --
+  --testdir "${TEST_SRC_DIR}/constraints"
+)
+
 # ------------------------------------------------------------------------------
 # OPERATORS TESTS
 add_blender_test(
diff --git a/tests/python/bl_constraints.py b/tests/python/bl_constraints.py
new file mode 100644
index 00000000000..1b3ced9b4d7
--- /dev/null
+++ b/tests/python/bl_constraints.py
@@ -0,0 +1,179 @@
+# ##### 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 #####
+
+"""
+./blender.bin --background -noaudio --factory-startup --python tests/python/bl_constraints.py -- --testdir /path/to/lib/tests/constraints
+"""
+
+import pathlib
+import sys
+import unittest
+
+import bpy
+from mathutils import Matrix
+
+
+class AbstractConstraintTests(unittest.TestCase):
+    """Useful functionality for constraint tests."""
+
+    def setUp(self):
+        bpy.ops.wm.open_mainfile(filepath=str(args.testdir / "constraints.blend"))
+
+    def assert_matrix(self, actual, expect, places=6, delta=None):
+        """Asserts that the matrices almost equal."""
+        self.assertEqual(len(actual), 4, 'Expected a 4x4 matrix')
+
+        # TODO(Sybren): decompose the matrices and compare loc, rot, and scale separately.
+        # That'll probably improve readability & understandability of test failures.
+        for row, (act_row, exp_row) in enumerate(zip(actual, expect)):
+            for col, (act, exp) in enumerate(zip(act_row, exp_row)):
+                self.assertAlmostEqual(act, exp, places=places, delta=delta,
+                                       msg=f'{act} != {exp} at element [{row}][{col}]')
+
+    def matrix(self, object_name: str) -> Matrix:
+        """Return the evaluated world matrix."""
+        depsgraph = bpy.context.view_layer.depsgraph
+        depsgraph.update()
+        ob_orig = bpy.context.scene.objects[object_name]
+        ob_eval = ob_orig.evaluated_get(depsgraph)
+        return ob_eval.matrix_world
+
+    def matrix_test(self, object_name: str, expect: Matrix):
+        """Assert that the object's world matrix is as expected."""
+        actual = self.matrix(object_name)
+        self.assert_matrix(actual, expect)
+
+    def constraint_context(self, constraint_name: str) -> dict:
+        """Return a context suitable for calling constraint operators.
+
+        Assumes the owner is called "{constraint_name}.owner".
+        """
+        owner = bpy.context.scene.objects['Child Of.owner']
+        constraint = owner.constraints[constraint_name]
+        context = {
+            **bpy.context.copy(),
+            'constraint': constraint,
+        }
+        return context
+
+class ChildOfTest(AbstractConstraintTests):
+    def test_childof_simple_parent(self):
+        """Child Of: simple evaluation."""
+        initial_matrix = Matrix((
+            (0.5872668623924255, -0.3642929494380951, 0.29567837715148926, 1.0886117219924927),
+            (0.31689348816871643, 0.7095895409584045, 0.05480116978287697, 2.178966999053955),
+            (-0.21244174242019653, 0.06738340109586716, 0.8475662469863892, 3.2520291805267334),
+            (0.0, 0.0, 0.0, 1.0),
+        ))
+        self.matrix_test('Child Of.owner', initial_matrix)
+
+        context = self.constraint_context('Child Of')
+        bpy.ops.constraint.childof_set_inverse(context, constraint='Child Of')
+        self.matrix_test('Child Of.owner', Matrix((
+            (0.9992385506629944, 0.019844001159071922, -0.03359175845980644, 0.10000011324882507),
+            (-0.01744179055094719, 0.997369647026062, 0.07035345584154129, 0.1999998837709427),
+            (0.034899525344371796, -0.06971397250890732, 0.9969563484191895, 0.3000001311302185),
+            (0.0, 0.0, 0.0, 1.0),
+        )))
+
+        bpy.ops.constraint.childof_clear_inverse(context, constraint='Child Of')
+        self.matrix_test('Child Of.owner', initial_matrix)
+
+    def test_childof_rotation_only(self):
+        """Child Of: rotation only."""
+        owner = bpy.context.scene.objects['Child Of.owner']
+        constraint = owner.constraints['Child Of']
+        constraint.use_location_x = constraint.use_location_y = constraint.use_location_z = False
+        constraint.use_scale_x = constraint.use_scale_y = constraint.use_scale_z = False
+
+        initial_matrix = Matrix((
+            (0.8340795636177063, -0.4500490725040436, 0.31900957226753235, 0.10000000149011612),
+            (0.4547243118286133, 0.8883093595504761, 0.06428192555904388, 0.20000000298023224),
+            (-0.31230923533439636, 0.09144517779350281, 0.9455690383911133, 0.30000001192092896),
+            (0.0, 0.0, 0.0, 1.0),
+        ))
+        self.matrix_test('Child Of.owner', initial_matrix)
+
+        context = self.constraint_context('Child Of')
+        bpy.ops.constraint.childof_set_inverse(context, constraint='Child Of')
+        self.matrix_test('Child Of.owner', Matrix((
+            (0.9992386102676392, 0.019843975082039833, -0.033591702580451965, 0.10000000149011612),
+            (-0.017441781237721443, 0.9973695874214172, 0.0703534483909607, 0.20000000298023224),
+            (0.03489946573972702, -0.06971397250890732, 0.9969563484191895, 0.30000001192092896),
+            (0.0, 0.0, 0.0, 1.0),
+        )))
+
+        bpy.ops.constraint.childof_clear_inverse(context, constraint='Child Of')
+        self.matrix_test('Child Of.owner', initial_matrix)
+
+
+    def test_childof_no_x_axis(self):
+        """Child Of: loc/rot/scale on only Y and Z axes."""
+        owner = bpy.context.scene.objects['Child Of.owner']
+        constraint = owner.constraints['Child Of']
+        constraint.use_location_x = False
+        constraint.use_rotation_x = False
+        constraint.use_scale_x = False
+
+        initial_matrix = Matrix((
+            (0.8294582366943359, -0.4013831615447998, 0.2102886438369751, 0.10000000149011612),
+            (0.46277597546577454, 0.6895919442176819, 0.18639995157718658, 2.2317214012145996),
+            (-0.31224438548088074, -0.06574578583240509, 0.8546382784843445, 3.219514846801758),
+            (0.0, 0.0, 0.0, 1.0),
+        ))
+        self.matrix_test('Child Of.owner', initial_matrix)
+
+        context = self.constraint_context('Child Of')
+        bpy.ops.constraint.childof_set_inverse(context, constraint='Child Of')
+        self.matrix_test('Child Of.owner', Matrix((
+            (0.9228900671005249, 0.23250490427017212, -0.035540513694286346, 0.10000000149011612),
+            (-0.011224273592233658, 0.9838480949401855, 0.24731633067131042, 0.21246682107448578),
+            (0.0383986234664917, -0.3163823187351227, 0.9553266167640686, 0.27248233556747437),
+            (0.0, 0.0, 0.0, 1.0),
+        )))
+
+        bpy.ops.constraint.childof_clear_inverse(context, constraint='Child Of')
+        self.matrix_test('Child Of.owner', initial_matrix)
+
+
+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)