Catch zstandard warning (existed prior to PR #231)

tests/memory_test.py

@@ -1,6 +1,7 @@
 """
 Simple test for evaluating zstandard binding memory usage.
 """
+
 import io
 import sys
 

tests/test_degraded.py

@@ -6,6 +6,7 @@
 import importlib
 import subprocess
 import sys
+import warnings
 
 
 def test_degraded():
@@ -17,7 +18,13 @@ def test_degraded():
         # this is only testing conda_package_handling's code, and does not test
         # that conda_package_streaming works without zstandard.
 
-        import conda_package_handling.api
+        with warnings.catch_warnings(record=True) as w:
+            warnings.simplefilter("always")  # Ensure warnings are sent
+            import conda_package_handling.api
+
+            assert len(w) == 1
+            assert issubclass(w[-1].category, UserWarning)
+            assert "zstandard" in str(w[-1].message)
 
         importlib.reload(conda_package_handling.api)