useless-exception-statement (PLW0133)

Derived from the Pylint linter.

Fix is sometimes available.

This rule is unstable and in preview. The --preview flag is required for use.

What it does

Checks for an exception that is not raised.

Why is this bad?

It's unnecessary to create an exception without raising it. For example, ValueError("...") on its own will have no effect (unlike raise ValueError("...")) and is likely a mistake.

Known problems

This rule only detects built-in exceptions, like ValueError, and does not catch user-defined exceptions.

Example

ValueError("...")

Use instead:

raise ValueError("...")

Fix safety

This rule's fix is marked as unsafe, as converting a useless exception statement to a raise statement will change the program's behavior.