Improve exception trace with RUF B904 (#1641)

Co-authored-by: Martin Durant <[email protected]>

Author: Skylion007

fsspec/core.py

@@ -639,7 +639,7 @@ def get_fs_token_paths(
     if isinstance(urlpath, (list, tuple, set)):
         if not urlpath:
             raise ValueError("empty urlpath sequence")
-        urlpath0 = stringify_path(list(urlpath)[0])
+        urlpath0 = stringify_path(next(iter(urlpath)))
     else:
         urlpath0 = stringify_path(urlpath)
     storage_options = storage_options or {}

fsspec/fuse.py

@@ -31,8 +31,8 @@ def getattr(self, path, fh=None):
         path = "".join([self.root, path.lstrip("/")]).rstrip("/")
         try:
             info = self.fs.info(path)
-        except FileNotFoundError:
-            raise FuseOSError(ENOENT)
+        except FileNotFoundError as exc:
+            raise FuseOSError(ENOENT) from exc
 
         data = {"st_uid": info.get("uid", 1000), "st_gid": info.get("gid", 1000)}
         perm = info.get("mode", 0o777)
@@ -119,8 +119,8 @@ def unlink(self, path):
         fn = "".join([self.root, path.lstrip("/")])
         try:
             self.fs.rm(fn, False)
-        except (OSError, FileNotFoundError):
-            raise FuseOSError(EIO)
+        except (OSError, FileNotFoundError) as exc:
+            raise FuseOSError(EIO) from exc
 
     def release(self, path, fh):
         try:

fsspec/gui.py

@@ -93,8 +93,10 @@ def _repr_mimebundle_(self, *args, **kwargs):
         """Display in a notebook or a server"""
         try:
             return self.panel._repr_mimebundle_(*args, **kwargs)
-        except (ValueError, AttributeError):
-            raise NotImplementedError("Panel does not seem to be set up properly")
+        except (ValueError, AttributeError) as exc:
+            raise NotImplementedError(
+                "Panel does not seem to be set up properly"
+            ) from exc
 
     def connect(self, signal, slot):
         """Associate call back with given event

fsspec/implementations/dbfs.py

@@ -77,7 +77,7 @@ def ls(self, path, detail=True, **kwargs):
                 )
             except DatabricksException as e:
                 if e.error_code == "RESOURCE_DOES_NOT_EXIST":
-                    raise FileNotFoundError(e.message)
+                    raise FileNotFoundError(e.message) from e
 
                 raise e
             files = r["files"]
@@ -123,7 +123,7 @@ def makedirs(self, path, exist_ok=True):
             self._send_to_api(method="post", endpoint="mkdirs", json={"path": path})
         except DatabricksException as e:
             if e.error_code == "RESOURCE_ALREADY_EXISTS":
-                raise FileExistsError(e.message)
+                raise FileExistsError(e.message) from e
 
             raise e
         self.invalidate_cache(self._parent(path))
@@ -169,7 +169,7 @@ def rm(self, path, recursive=False, **kwargs):
                 self.rm(path=path, recursive=recursive)
             elif e.error_code == "IO_ERROR":
                 # Using the same exception as the os module would use here
-                raise OSError(e.message)
+                raise OSError(e.message) from e
 
             raise e
         self.invalidate_cache(self._parent(path))
@@ -212,9 +212,9 @@ def mv(
             )
         except DatabricksException as e:
             if e.error_code == "RESOURCE_DOES_NOT_EXIST":
-                raise FileNotFoundError(e.message)
+                raise FileNotFoundError(e.message) from e
             elif e.error_code == "RESOURCE_ALREADY_EXISTS":
-                raise FileExistsError(e.message)
+                raise FileExistsError(e.message) from e
 
             raise e
         self.invalidate_cache(self._parent(source_path))
@@ -264,9 +264,9 @@ def _send_to_api(self, method, endpoint, json):
             try:
                 exception_json = e.response.json()
             except Exception:
-                raise e
+                raise e from None
 
-            raise DatabricksException(**exception_json)
+            raise DatabricksException(**exception_json) from e
 
         return r.json()
 
@@ -297,7 +297,7 @@ def _create_handle(self, path, overwrite=True):
             return r["handle"]
         except DatabricksException as e:
             if e.error_code == "RESOURCE_ALREADY_EXISTS":
-                raise FileExistsError(e.message)
+                raise FileExistsError(e.message) from e
 
             raise e
 
@@ -314,7 +314,7 @@ def _close_handle(self, handle):
             self._send_to_api(method="post", endpoint="close", json={"handle": handle})
         except DatabricksException as e:
             if e.error_code == "RESOURCE_DOES_NOT_EXIST":
-                raise FileNotFoundError(e.message)
+                raise FileNotFoundError(e.message) from e
 
             raise e
 
@@ -342,9 +342,9 @@ def _add_data(self, handle, data):
             )
         except DatabricksException as e:
             if e.error_code == "RESOURCE_DOES_NOT_EXIST":
-                raise FileNotFoundError(e.message)
+                raise FileNotFoundError(e.message) from e
             elif e.error_code == "MAX_BLOCK_SIZE_EXCEEDED":
-                raise ValueError(e.message)
+                raise ValueError(e.message) from e
 
             raise e
 
@@ -372,9 +372,9 @@ def _get_data(self, path, start, end):
             return base64.b64decode(r["data"])
         except DatabricksException as e:
             if e.error_code == "RESOURCE_DOES_NOT_EXIST":
-                raise FileNotFoundError(e.message)
+                raise FileNotFoundError(e.message) from e
             elif e.error_code in ["INVALID_PARAMETER_VALUE", "MAX_READ_SIZE_EXCEEDED"]:
-                raise ValueError(e.message)
+                raise ValueError(e.message) from e
 
             raise e
 

fsspec/implementations/ftp.py

@@ -122,8 +122,8 @@ def ls(self, path, detail=True, **kwargs):
                     info = self.info(path)
                     if info["type"] == "file":
                         out = [(path, info)]
-                except (Error, IndexError):
-                    raise FileNotFoundError(path)
+                except (Error, IndexError) as exc:
+                    raise FileNotFoundError(path) from exc
         files = self.dircache.get(path, out)
         if not detail:
             return sorted([fn for fn, details in files])
@@ -137,9 +137,9 @@ def info(self, path, **kwargs):
             return {"name": "/", "size": 0, "type": "directory"}
         files = self.ls(self._parent(path).lstrip("/"), True)
         try:
-            out = [f for f in files if f["name"] == path][0]
-        except IndexError:
-            raise FileNotFoundError(path)
+            out = next(f for f in files if f["name"] == path)
+        except StopIteration as exc:
+            raise FileNotFoundError(path) from exc
         return out
 
     def get_file(self, rpath, lpath, **kwargs):

fsspec/implementations/memory.py

@@ -224,8 +224,8 @@ def cat_file(self, path, start=None, end=None, **kwargs):
         path = self._strip_protocol(path)
         try:
             return bytes(self.store[path].getbuffer()[start:end])
-        except KeyError:
-            raise FileNotFoundError(path)
+        except KeyError as e:
+            raise FileNotFoundError(path) from e
 
     def _rm(self, path):
         path = self._strip_protocol(path)
@@ -238,15 +238,15 @@ def modified(self, path):
         path = self._strip_protocol(path)
         try:
             return self.store[path].modified
-        except KeyError:
-            raise FileNotFoundError(path)
+        except KeyError as e:
+            raise FileNotFoundError(path) from e
 
     def created(self, path):
         path = self._strip_protocol(path)
         try:
             return self.store[path].created
-        except KeyError:
-            raise FileNotFoundError(path)
+        except KeyError as e:
+            raise FileNotFoundError(path) from e
 
     def rm(self, path, recursive=False, maxdepth=None):
         if isinstance(path, str):

fsspec/implementations/reference.py

@@ -35,7 +35,7 @@ def __str__(self):
 
 
 def _first(d):
-    return list(d.values())[0]
+    return next(iter(d.values()))
 
 
 def _prot_in_references(path, references):
@@ -291,8 +291,8 @@ def _load_one_key(self, key):
         # Chunk keys can be loaded from row group and cached in LRU cache
         try:
             refs = self.open_refs(field, record)
-        except (ValueError, TypeError, FileNotFoundError):
-            raise KeyError(key)
+        except (ValueError, TypeError, FileNotFoundError) as exc:
+            raise KeyError(key) from exc
         columns = ["path", "offset", "size", "raw"]
         selection = [refs[c][ri] if c in refs else None for c in columns]
         raw = selection[-1]
@@ -732,8 +732,8 @@ def _cat_common(self, path, start=None, end=None):
         logger.debug(f"cat: {path}")
         try:
             part = self.references[path]
-        except KeyError:
-            raise FileNotFoundError(path)
+        except KeyError as exc:
+            raise FileNotFoundError(path) from exc
         if isinstance(part, str):
             part = part.encode()
         if isinstance(part, bytes):

fsspec/implementations/tests/test_cached.py

@@ -685,7 +685,9 @@ def test_local_filecache_basic(local_filecache):
     assert "cache" in os.listdir(cache_location)
 
     # the file in the location contains the right data
-    fn = list(fs._metadata.cached_files[-1].values())[0]["fn"]  # this is a hash value
+    fn = next(iter(fs._metadata.cached_files[-1].values()))[
+        "fn"
+    ]  # this is a hash value
     assert fn in os.listdir(cache_location)
     with open(os.path.join(cache_location, fn), "rb") as f:
         assert f.read() == data
@@ -730,7 +732,9 @@ def test_local_filecache_gets_from_original_if_cache_deleted(local_filecache):
         assert f.read() == new_data
 
     # the file in the location contains the right data
-    fn = list(fs._metadata.cached_files[-1].values())[0]["fn"]  # this is a hash value
+    fn = next(iter(fs._metadata.cached_files[-1].values()))[
+        "fn"
+    ]  # this is a hash value
     assert fn in os.listdir(cache_location)
     with open(os.path.join(cache_location, fn), "rb") as f:
         assert f.read() == new_data
@@ -753,7 +757,7 @@ def test_local_filecache_with_new_cache_location_makes_a_new_copy(local_filecach
         assert f.read() == data
 
     # the file in the location contains the right data
-    fn = list(new_fs._metadata.cached_files[-1].values())[0][
+    fn = next(iter(new_fs._metadata.cached_files[-1].values()))[
         "fn"
     ]  # this is a hash value
     assert fn in os.listdir(old_cache_location)

fsspec/mapping.py

@@ -153,10 +153,10 @@ def __getitem__(self, key, default=None):
         k = self._key_to_str(key)
         try:
             result = self.fs.cat(k)
-        except self.missing_exceptions:
+        except self.missing_exceptions as exc:
             if default is not None:
                 return default
-            raise KeyError(key)
+            raise KeyError(key) from exc
         return result
 
     def pop(self, key, default=None):
@@ -184,8 +184,8 @@ def __delitem__(self, key):
         """Remove key"""
         try:
             self.fs.rm(self._key_to_str(key))
-        except:  # noqa: E722
-            raise KeyError
+        except Exception as exc:
+            raise KeyError from exc
 
     def __contains__(self, key):
         """Does key exist in mapping?"""

pyproject.toml

@@ -154,6 +154,7 @@ select = [
     # fix noqas in fsspec/implementations/http.py
     "ASYNC",
     "B",
+    "B904",
     "C4",
     "G",
     "E4",
@@ -177,6 +178,7 @@ select = [
     # "PT", enable in later PR
     "PYI",
     "RUF006",
+    "RUF015",
     "RUF024",
     "SLOT",
     "SIM101",