tests: introduce ETagNotInResponseHeaderWarning to reduce warnings

dclab/http_utils.py

@@ -27,6 +27,10 @@
 )
 
 
+class ETagNotInResponseHeaderWarning(UserWarning):
+    """Used for cases where the requests.Response does not contain an ETag"""
+
+
 class HTTPFile(io.IOBase):
     def __init__(self, url, chunk_size=2**18, keep_chunks=200):
         """Chunk-cached access to a URL supporting range requests
@@ -78,7 +82,8 @@ def _parse_header(self):
             etag = resp.headers.get("etag", "").strip("'").strip('"')
             if len(etag) < 5:
                 etag = None
-                warnings.warn(f"Got empty ETag header for {self.url}")
+                warnings.warn(f"Got empty ETag header for {self.url}",
+                              ETagNotInResponseHeaderWarning)
             self._etag = etag
 
     @property

tests/test_rtdc_fmt_http_basin.py

@@ -7,6 +7,7 @@
 import pytest
 
 import dclab
+from dclab.http_utils import ETagNotInResponseHeaderWarning
 from dclab import new_dataset, RTDCWriter
 from dclab.rtdc_dataset.fmt_http import HTTPBasin, RTDC_HTTP
 from dclab.rtdc_dataset.feat_basin import BasinNotAvailableError
@@ -271,8 +272,12 @@ def test_trace_availability_invalid(tmp_path):
         # because `__contains__` returns True for "trace", but the trace data
         # are nowhere to find.
         with (pytest.warns(UserWarning, match="but I cannot get its data"),
+              pytest.warns(ETagNotInResponseHeaderWarning,
+                           match="Got empty ETag header"),
               pytest.raises(KeyError, match="trace")):
             _ = ds["trace"]
         with (pytest.warns(UserWarning, match="but I cannot get its data"),
+              pytest.warns(ETagNotInResponseHeaderWarning,
+                           match="Got empty ETag header"),
               pytest.raises(KeyError, match="trace")):
             dclab.new_dataset(ds)