fix: fetch-lib error message showing "Library None not found"

charmcraft/application/commands/store.py

@@ -1534,11 +1534,15 @@ def run(self, parsed_args: argparse.Namespace) -> None:
                     for lib in local_libs_data
                 ]
             )
-        except errors.LibraryError:
-            raise errors.LibraryError(
-                message=f"Library {parsed_args.library} not found in Charmhub.",
-                logpath_report=False,
-            )
+        except errors.LibraryError as e:
+            # If a specific library was requested, use that in the error message
+            # Otherwise, re-raise the original error which should have details
+            if parsed_args.library:
+                raise errors.LibraryError(
+                    message=f"Library {parsed_args.library} not found in Charmhub.",
+                    logpath_report=False,
+                ) from e
+            raise
 
         # check if something needs to be done
         analysis = []
@@ -1559,7 +1563,7 @@ def run(self, parsed_args: argparse.Namespace) -> None:
                     break
             else:
                 raise errors.LibraryError(
-                    message=f"Library {parsed_args.library} not found in Charmhub.",
+                    message=f"Library {lib_data.full_name} not found in Charmhub.",
                     logpath_report=False,
                 )
             emit.debug(f"Store tip: {tip}")

tests/integration/commands/test_store_commands.py

@@ -193,6 +193,38 @@ def test_fetchlib_store_not_found(
     )
 
 
+@pytest.mark.slow
+def test_fetchlib_all_library_not_found(
+    emitter: craft_cli.pytest_plugin.RecordingEmitter,
+    new_path: pathlib.Path,
+    config,
+) -> None:
+    """When fetching all libraries, if one is not found, show its name in error message."""
+    # Create a library with a fake lib_id that doesn't exist in Charmhub
+    # Using a lib_id that's clearly fake and won't match any real library
+    factory.create_lib_filepath(
+        "nonexistent-charm",
+        "nonexistent_lib",
+        api=0,
+        patch=1,
+        lib_id="00000000000000000000000000000000",
+    )
+
+    args = argparse.Namespace(library=None, format=None)
+
+    with pytest.raises(errors.LibraryError) as exc_info:
+        FetchLibCommand(config).run(args)
+
+    # The error message should contain the actual library name, not "None"
+    error_message = exc_info.value.args[0]
+    assert "charms.nonexistent_charm.v0.nonexistent_lib" in error_message
+    assert "None" not in error_message
+    # Verify the full error message format
+    assert error_message == (
+        "Library charms.nonexistent_charm.v0.nonexistent_lib not found in Charmhub."
+    )
+
+
 @pytest.mark.slow
 @pytest.mark.parametrize("formatted", [None, "json"])
 def test_fetchlib_store_is_old(

tests/spread/store/libraries-not-found/task.yaml

@@ -0,0 +1,46 @@
+---
+summary: test fetch-lib error message when library not found
+
+environment:
+  CHARM_NAME: nonexistent-charm-$(uuidgen | sed -e 's/-//g')
+
+include:
+  - tests/
+
+prepare: |
+  tests.pkgs install jq
+
+  # Create a temporary charm directory with a library that has a fake lib_id
+  mkdir -p charm/lib/charms/nonexistent_charm/v0
+
+  # Create a library file with metadata that won't exist in Charmhub
+  cat > charm/lib/charms/nonexistent_charm/v0/fake_lib.py << 'EOF'
+  # Test library with fake ID
+  LIBID = "00000000000000000000000000000000"
+  LIBAPI = 0
+  LIBPATCH = 1
+
+  # Some library code
+  def test_function():
+      pass
+  EOF
+
+restore: |
+  rm -rf charm
+
+execute: |
+  cd charm
+
+  # Try to fetch all libraries (without specifying a library name)
+  # This should fail with error showing library name, not "None"
+  output=$(charmcraft fetch-lib 2>&1) && exit 1 || true
+
+  # Verify the error message contains the library name
+  echo "$output" | MATCH "charms.nonexistent_charm.v0.fake_lib"
+
+  # Verify the error message does NOT contain "Library None"
+  echo "$output" | NOMATCH "Library None"
+
+  # Verify the full error message format
+  echo "$output" | \
+    MATCH "Library charms.nonexistent_charm.v0.fake_lib not found"