len-test (PLC1802)

Derived from the Pylint linter.

Fix is always available.

What it does

Checks for len calls on sequences in a boolean test context.

Empty sequences are considered false in a boolean context. You can either remove the call to len or compare the length against a scalar.

fruits = ["orange", "apple"]
vegetables = []

if len(fruits):
    print(fruits)

if not len(vegetables):
    print(vegetables)

Use instead:

fruits = ["orange", "apple"]
vegetables = []

if fruits:
    print(fruits)

if not vegetables:
    print(vegetables)