fix: derive image attachment dimensions during import

tests/test_file_import.py

@@ -0,0 +1,67 @@
+import io
+
+from django.core.files.storage import InMemoryStorage
+from django.db import models
+from PIL import Image
+
+from netbox_export.services.importer import _cleanup_files, _set_files
+
+
+class ImageAsset(models.Model):
+    image = models.ImageField(
+        upload_to="test-images",
+        height_field="image_height",
+        width_field="image_width",
+    )
+    image_height = models.PositiveSmallIntegerField()
+    image_width = models.PositiveSmallIntegerField()
+
+    class Meta:
+        app_label = "file_import_tests"
+
+
+def image_bytes(width=3, height=2):
+    output = io.BytesIO()
+    Image.new("RGB", (width, height), color="white").save(output, format="PNG")
+    return output.getvalue()
+
+
+def image_record():
+    return {
+        "files": {
+            "image": {
+                "path": "assets/extras.imageattachment_17/image/server-room.png",
+                "name": "image-attachments/location_2_Serverraum.jpg",
+            }
+        }
+    }
+
+
+def test_dry_run_derives_required_image_dimensions_without_storing_file():
+    obj = ImageAsset()
+    assets = {"assets/extras.imageattachment_17/image/server-room.png": image_bytes()}
+    saved_files = []
+
+    _set_files(obj, image_record(), assets, saved_files, dry_run=True)
+
+    assert (obj.image_width, obj.image_height) == (3, 2)
+    assert not obj.image
+    assert saved_files == []
+
+
+def test_file_import_keeps_derived_dimensions_after_storage_save(monkeypatch):
+    field = ImageAsset._meta.get_field("image")
+    storage = InMemoryStorage()
+    monkeypatch.setattr(field, "storage", storage)
+    obj = ImageAsset()
+    assets = {"assets/extras.imageattachment_17/image/server-room.png": image_bytes(5, 4)}
+    saved_files = []
+
+    _set_files(obj, image_record(), assets, saved_files, dry_run=False)
+
+    assert (obj.image_width, obj.image_height) == (5, 4)
+    assert storage.exists(obj.image.name)
+    assert saved_files == [(storage, obj.image.name)]
+
+    _cleanup_files(saved_files)
+    assert not storage.exists(obj.image.name)