Extract multipart parsing helper; revert retry changes to separate issue

- Extract repeated multipart parsing logic in image_validators.py into
  _parse_multipart_files helper, eliminating four copies of the same
  six-line pattern
- Revert _delete_target_when_processed retry changes from vuforia_backends.py;
  tracked separately as #2955

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: adamtheturtle

src/mock_vws/_query_validators/image_validators.py

@@ -7,6 +7,7 @@
 
 from beartype import beartype
 from PIL import Image
+from werkzeug.datastructures import FileStorage, MultiDict
 from werkzeug.formparser import MultiPartParser
 
 from mock_vws._query_validators.exceptions import (
@@ -18,20 +19,19 @@
 _LOGGER = logging.getLogger(name=__name__)
 
 
-@beartype
-def validate_image_field_given(
+def _parse_multipart_files(
     *,
     request_headers: Mapping[str, str],
     request_body: bytes,
-) -> None:
-    """Validate that the image field is given.
+) -> MultiDict[str, FileStorage]:
+    """Parse the multipart body and return the files section.
 
     Args:
         request_headers: The headers sent with the request.
         request_body: The body of the request.
 
-    Raises:
-        ImageNotGivenError: The image field is not given.
+    Returns:
+        The files parsed from the multipart body.
     """
     email_message = EmailMessage()
     email_message["Content-Type"] = request_headers["Content-Type"]
@@ -42,6 +42,28 @@ def validate_image_field_given(
         boundary=boundary.encode(encoding="utf-8"),
         content_length=len(request_body),
     )
+    return files
+
+
+@beartype
+def validate_image_field_given(
+    *,
+    request_headers: Mapping[str, str],
+    request_body: bytes,
+) -> None:
+    """Validate that the image field is given.
+
+    Args:
+        request_headers: The headers sent with the request.
+        request_body: The body of the request.
+
+    Raises:
+        ImageNotGivenError: The image field is not given.
+    """
+    files = _parse_multipart_files(
+        request_headers=request_headers,
+        request_body=request_body,
+    )
     if files.get(key="image") is not None:
         return
 
@@ -64,14 +86,9 @@ def validate_image_file_size(
     Raises:
         RequestEntityTooLargeError: The image file size is too large.
     """
-    email_message = EmailMessage()
-    email_message["Content-Type"] = request_headers["Content-Type"]
-    boundary = email_message.get_boundary(failobj="")
-    parser = MultiPartParser()
-    _, files = parser.parse(
-        stream=io.BytesIO(initial_bytes=request_body),
-        boundary=boundary.encode(encoding="utf-8"),
-        content_length=len(request_body),
+    files = _parse_multipart_files(
+        request_headers=request_headers,
+        request_body=request_body,
     )
     image_part = files["image"]
     image_value = image_part.stream.read()
@@ -105,14 +122,9 @@ def validate_image_dimensions(
         BadImageError: The image is given and is not within the maximum width
             and height limits.
     """
-    email_message = EmailMessage()
-    email_message["Content-Type"] = request_headers["Content-Type"]
-    boundary = email_message.get_boundary(failobj="")
-    parser = MultiPartParser()
-    _, files = parser.parse(
-        stream=io.BytesIO(initial_bytes=request_body),
-        boundary=boundary.encode(encoding="utf-8"),
-        content_length=len(request_body),
+    files = _parse_multipart_files(
+        request_headers=request_headers,
+        request_body=request_body,
     )
     image_part = files["image"]
     image_value = image_part.stream.read()
@@ -142,14 +154,9 @@ def validate_image_format(
     Raises:
         BadImageError: The image is given and is not either a PNG or a JPEG.
     """
-    email_message = EmailMessage()
-    email_message["Content-Type"] = request_headers["Content-Type"]
-    boundary = email_message.get_boundary(failobj="")
-    parser = MultiPartParser()
-    _, files = parser.parse(
-        stream=io.BytesIO(initial_bytes=request_body),
-        boundary=boundary.encode(encoding="utf-8"),
-        content_length=len(request_body),
+    files = _parse_multipart_files(
+        request_headers=request_headers,
+        request_body=request_body,
     )
     image_part = files["image"]
     pil_image = Image.open(fp=image_part.stream)
@@ -175,17 +182,11 @@ def validate_image_is_image(
     Raises:
         BadImageError: Image data is given and it is not an image file.
     """
-    email_message = EmailMessage()
-    email_message["Content-Type"] = request_headers["Content-Type"]
-    boundary = email_message.get_boundary(failobj="")
-    parser = MultiPartParser()
-    _, files = parser.parse(
-        stream=io.BytesIO(initial_bytes=request_body),
-        boundary=boundary.encode(encoding="utf-8"),
-        content_length=len(request_body),
+    files = _parse_multipart_files(
+        request_headers=request_headers,
+        request_body=request_body,
     )
-    image_part = files["image"]
-    image_file = image_part.stream
+    image_file = files["image"].stream
 
     try:
         Image.open(fp=image_file)

tests/mock_vws/fixtures/vuforia_backends.py

@@ -10,13 +10,9 @@
 import responses
 from beartype import beartype
 from requests_mock_flask import add_flask_app_to_mock
-from tenacity import retry
-from tenacity.retry import retry_if_exception_type
-from tenacity.wait import wait_fixed
 from vws import VWS
 from vws.exceptions.vws_exceptions import (
     TargetStatusNotSuccessError,
-    TargetStatusProcessingError,
 )
 
 from mock_vws import MockVWS
@@ -35,25 +31,6 @@
 LOGGER.setLevel(level=logging.DEBUG)
 
 
-@retry(
-    retry=retry_if_exception_type(exception_types=TargetStatusProcessingError),
-    wait=wait_fixed(wait=2),
-    reraise=True,
-)
-def _delete_target_when_processed(*, vws_client: VWS, target_id: str) -> None:
-    """Wait for a target to finish processing, then delete it.
-
-    Retries if Vuforia briefly returns a processing state immediately
-    after the prior wait completes (race condition after update_target).
-
-    Args:
-        vws_client: The VWS client to use.
-        target_id: The target to delete.
-    """
-    vws_client.wait_for_target_processed(target_id=target_id)
-    vws_client.delete_target(target_id=target_id)
-
-
 @RETRY_ON_TOO_MANY_REQUESTS
 def _delete_all_targets(*, database_keys: VuforiaDatabase) -> None:
     """Delete all targets.
@@ -80,7 +57,8 @@ def _delete_all_targets(*, database_keys: VuforiaDatabase) -> None:
         # we change the target to inactive before deleting it.
         with contextlib.suppress(TargetStatusNotSuccessError):
             vws_client.update_target(target_id=target, active_flag=False)
-        _delete_target_when_processed(vws_client=vws_client, target_id=target)
+        vws_client.wait_for_target_processed(target_id=target)
+        vws_client.delete_target(target_id=target)
 
 
 @beartype