single-item-membership-test (FURB171)
Derived from the refurb linter.
Fix is sometimes available.
This rule is unstable and in preview. The --preview flag is required for use.
What it does
Checks for membership tests against single-item containers.
Why is this bad?
Performing a membership test against a container (like a list or set)
with a single item is less readable and less efficient than comparing
against the item directly.
Example
Use instead:
Fix safety
The fix is always marked as unsafe.
When the right-hand side is a string, this fix can change the behavior of your program.
This is because c in "a" is true both when c is "a" and when c is the empty string.
Additionally, converting in/not in against a single-item container to ==/!= can
change runtime behavior: in may consider identity (e.g., NaN) and always
yields a bool.
Comments within the replacement range will also be removed.