Fix UnboundLocalError: cannot access local variable 'url'

pictures/templatetags/pictures.py

@@ -1,3 +1,5 @@
+import warnings
+
 from django import template
 from django.template import loader
 
@@ -68,6 +70,12 @@ def img_url(field_file, file_type, width, ratio=None) -> str:
         raise ValueError(
             f"Invalid file type: {file_type}. Choices are: {', '.join(file_types.keys())}"
         ) from e
+    url = field_file.url
+    if not sizes.items():
+        warnings.warn(
+            "Image is smaller than requested size, using source file URL.",
+            stacklevel=2,
+        )
     for w, img in sorted(sizes.items()):
         url = img.url
         if w >= int(width):

tests/conftest.py

@@ -17,6 +17,15 @@ def image_upload_file():
         return SimpleUploadedFile("image.png", output.getvalue())
 
 
+@pytest.fixture
+def tiny_image_upload_file():
+    img = Image.new("RGBA", (1, 1), (255, 55, 255, 1))
+
+    with io.BytesIO() as output:
+        img.save(output, format="PNG")
+        return SimpleUploadedFile("image.png", output.getvalue())
+
+
 @pytest.fixture(autouse=True, scope="function")
 def media_root(settings, tmpdir_factory):
     settings.MEDIA_ROOT = tmpdir_factory.mktemp("media", numbered=True)

tests/test_templatetags.py

@@ -111,3 +111,18 @@ def test_img_url__raise_wrong_file_type(image_upload_file):
     with pytest.raises(ValueError) as e:
         img_url(profile.picture, ratio="3/2", file_type="gif", width=800)
     assert "Invalid file type: gif. Choices are: WEBP" in str(e.value)
+
+
+@pytest.mark.django_db
+def test_img_url__too_small(tiny_image_upload_file, caplog):
+    profile = Profile.objects.create(name="Spiderman", picture=tiny_image_upload_file)
+    with pytest.warns() as record:
+        assert (
+            img_url(profile.picture, ratio="3/2", file_type="webp", width="800")
+            == "/media/testapp/profile/image.png"
+        )
+    assert len(record) == 1
+    assert (
+        "Image is smaller than requested size, using source file URL."
+        in record[0].message.args[0]
+    )