more precise log for non-UTF-8 text-like

Author: rgaudin

src/zimscraperlib/zim/creator.py

@@ -183,7 +183,8 @@ def _log_metadata(self):
                     logger.debug(f"Metadata: {name} = {value.decode('UTF-8')}")
                 except Exception:
                     logger.debug(
-                        f"Metadata: {name} is a {len(value)} bytes {mimetype} blob"
+                        f"Metadata: {name} is a {len(value)} bytes {mimetype} blob "
+                        "not decodable as an UTF-8 string"
                     )
                 continue
 

tests/zim/test_zim_creator.py

@@ -604,7 +604,10 @@ def __str__(self):
     mocked_logger.debug.assert_has_calls(
         [
             call("Metadata: Chars = šɔɛ"),
-            call("Metadata: Chars-32 is a 16 bytes text/plain blob"),
+            call(
+                "Metadata: Chars-32 is a 16 bytes text/plain blob "
+                "not decodable as an UTF-8 string"
+            ),
             call("Metadata: Creator = English speaking Wikipedia contributors"),
             call("Metadata: Date = 2009-11-21"),
             call(