Restore test_preflight.py from Make-It-Animatable

test_preflight.py

@@ -0,0 +1,62 @@
+import json
+import struct
+import tempfile
+import unittest
+from pathlib import Path
+from preflight import inspect_glb
+
+class PreflightTests(unittest.TestCase):
+    def write_fixture(self, root, faces, copies=1):
+        # Valid unindexed triangles. Repeated triangle vertices exercise the
+        # parser with real binary payload, without a 2M-face Python object graph.
+        count = faces * 3
+        doc = {"asset":{"version":"2.0"}, "buffers":[{"byteLength":count*12}],
+               "bufferViews":[{"buffer":0,"byteLength":count*12}],
+               "accessors":[{"bufferView":0,"componentType":5126,"count":count,
+                             "type":"VEC3","min":[0,0,0],"max":[1,1,0]}],
+               "meshes":[{"primitives":[{"attributes":{"POSITION":0}}]}],
+               "nodes":[{"mesh":0} for _ in range(copies)],
+               "scenes":[{"nodes":list(range(copies))}],"scene":0}
+        payload = json.dumps(doc).encode()
+        payload += b" " * (-len(payload) % 4)
+        p = Path(root)/"fixture.glb"
+        with p.open("wb") as stream:
+            stream.write(struct.pack("<4sIIII", b"glTF",2,28+len(payload)+count*12,len(payload),0x4E4F534A))
+            stream.write(payload)
+            stream.write(struct.pack("<II",count*12,0x004E4942))
+            triangle = struct.pack("<9f",0,0,0,1,0,0,0,1,0)
+            block = triangle * 1000
+            for _ in range(faces//1000):
+                stream.write(block)
+            stream.write(triangle * (faces%1000))
+        return p
+
+    def test_normal(self):
+        with tempfile.TemporaryDirectory() as root:
+            result = inspect_glb(self.write_fixture(root,12))
+            self.assertTrue(result["inference_allowed"])
+            self.assertEqual(result["triangles"],12)
+
+    def test_two_million_faces_preserved_and_blocked(self):
+        with tempfile.TemporaryDirectory() as root:
+            path = self.write_fixture(root,2_000_000)
+            before = path.stat()
+            result = inspect_glb(path)
+            self.assertEqual(result["triangles"],2_000_000)
+            self.assertFalse(result["inference_allowed"])
+            self.assertIn("decimation required",result["warning"])
+            self.assertEqual(path.stat().st_size,before.st_size)
+            self.assertEqual(path.stat().st_mtime_ns,before.st_mtime_ns)
+
+    def test_instances_count_towards_limit(self):
+        with tempfile.TemporaryDirectory() as root:
+            result = inspect_glb(self.write_fixture(root,100_000,6))
+            self.assertFalse(result["inference_allowed"])
+            self.assertEqual(result["instantiated_triangles"],600_000)
+
+    def test_truncated_rejected(self):
+        with tempfile.TemporaryDirectory() as root:
+            path=Path(root)/"bad.glb"
+            path.write_bytes(b"glTF")
+            with self.assertRaises(ValueError):
+                inspect_glb(path)