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compare-to-empty-string (PLC1901)#

Derived from the Pylint linter.

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

What it does#

Checks for comparisons to empty strings.

Why is this bad?#

An empty string is falsy, so it is unnecessary to compare it to "". If the value can be something else Python considers falsy, such as None or 0 or another empty container, then the code is not equivalent.

Known problems#

High false positive rate, as the check is context-insensitive and does not consider the type of the variable being compared (#4282).

Example#

x: str = ...

if x == "":
    print("x is empty")

Use instead: 

x: str = ...

if not x:
    print("x is empty")

References#