Fix type checking errors (#6016)

cylc/flow/clean.py

@@ -42,6 +42,7 @@
     Optional,
     Set,
     Union,
+    cast,
 )
 
 from cylc.flow import LOG
@@ -399,7 +400,7 @@ def remote_clean(
             excp = PlatformError(
                 PlatformError.MSG_TIDY,
                 this_platform['name'],
-                cmd=item.proc.args,
+                cmd=cast('List[str]', item.proc.args),
                 ret_code=ret_code,
                 out=out,
                 err=err,

cylc/flow/exceptions.py

@@ -19,8 +19,8 @@
 from textwrap import wrap
 from typing import (
     Dict,
-    Iterable,
     Optional,
+    Sequence,
     Union,
     TYPE_CHECKING,
 )
@@ -184,7 +184,7 @@ def __init__(
         platform_name: str,
         *,
         ctx: 'Optional[SubFuncContext]' = None,
-        cmd: Optional[Union[str, Iterable]] = None,
+        cmd: Union[str, Sequence[str], None] = None,
         ret_code: Optional[int] = None,
         out: Optional[str] = None,
         err: Optional[str] = None
@@ -419,13 +419,12 @@ def get_hint(self):
             )
         ):
             # likely an issue with the ranking expression
-            ranking = "\n".join(
-                wrap(
-                    self.data.get("ranking"),
-                    initial_indent='    ',
-                    subsequent_indent='    ',
-                )
+            lines = wrap(
+                self.data.get("ranking"),
+                initial_indent='    ',
+                subsequent_indent='    ',
             )
+            ranking = "\n".join(lines)
             return (
                 'This is likely an error in the ranking expression:'
                 f'\n{ranking}'

cylc/flow/task_remote_mgr.py

@@ -41,6 +41,7 @@
     Set,
     TYPE_CHECKING,
     Tuple,
+    cast,
 )
 
 from cylc.flow import LOG
@@ -434,7 +435,7 @@ def remote_tidy(self) -> None:
                     PlatformError(
                         PlatformError.MSG_TIDY,
                         item.platform['name'],
-                        cmd=item.proc.args,
+                        cmd=cast('List[str]', item.proc.args),
                         ret_code=item.proc.returncode,
                         out=out,
                         err=err
@@ -451,7 +452,7 @@ def remote_tidy(self) -> None:
                     PlatformError(
                         PlatformError.MSG_TIDY,
                         item.platform['name'],
-                        cmd=item.proc.args,
+                        cmd=cast('List[str]', item.proc.args),
                         ret_code=item.proc.returncode,
                         out=out,
                         err=err,
@@ -508,10 +509,8 @@ def _remote_init_callback(
                 install_target=install_target
             )
             old_umask = os.umask(0o177)
-            with open(
-                    public_key.full_key_path,
-                    'w', encoding='utf8') as text_file:
-                text_file.write(key)
+            with open(public_key.full_key_path, 'w', encoding='utf8') as f:
+                f.write(key)
             os.umask(old_umask)
             # configure_curve must be called every time certificates are
             # added or removed, in order to update the Authenticator's

cylc/flow/util.py

@@ -22,8 +22,7 @@
 from typing import (
     Any,
     List,
-    Tuple,
-    Union,
+    Sequence,
 )
 
 
@@ -77,7 +76,7 @@ def natural_sort(items: List[str], fcns=(int, str)) -> None:
     items.sort(key=partial(natural_sort_key, fcns=fcns))
 
 
-def format_cmd(cmd: Union[List[str], Tuple[str]], maxlen: int = 60) -> str:
+def format_cmd(cmd: Sequence[str], maxlen: int = 60) -> str:
     r"""Convert a shell command list to a user-friendly representation.
 
     Examples:

cylc/flow/workflow_files.py

@@ -110,15 +110,21 @@ class KeyInfo():  # noqa: SIM119 (not really relevant here)
 
     """
 
-    def __init__(self, key_type, key_owner, full_key_path=None,
-                 workflow_srv_dir=None, install_target=None, server_held=True):
+    def __init__(
+        self,
+        key_type: KeyType,
+        key_owner: KeyOwner,
+        full_key_path: Optional[str] = None,
+        workflow_srv_dir: Optional[str] = None,
+        install_target: Optional[str] = None,
+        server_held: bool = True
+    ):
         self.key_type = key_type
         self.key_owner = key_owner
-        self.full_key_path = full_key_path
         self.workflow_srv_dir = workflow_srv_dir
         self.install_target = install_target
-        if self.full_key_path is not None:
-            self.key_path, self.file_name = os.path.split(self.full_key_path)
+        if full_key_path is not None:
+            self.key_path, self.file_name = os.path.split(full_key_path)
         elif self.workflow_srv_dir is not None:  # noqa: SIM106
             # Build key filename
             file_name = key_owner.value
@@ -129,7 +135,7 @@ def __init__(self, key_type, key_owner, full_key_path=None,
                     and self.install_target is not None):
                 file_name = f"{file_name}_{self.install_target}"
 
-            if key_type == KeyType.PRIVATE:
+            if key_type is KeyType.PRIVATE:
                 file_extension = WorkflowFiles.Service.PRIVATE_FILE_EXTENSION
             else:
                 file_extension = WorkflowFiles.Service.PUBLIC_FILE_EXTENSION