Nrthugu

I have been able to have mypy do a type check on NamedTuple and use default values for NamedTuple.

However, I always have an error raised by mypy when I use default value.

Here is my code (I use Python 3.6)

class TestResult(NamedTuple):

    """To store results of a given Test Case"""



    outcome: str

    duration: Optional[int]  # in seconds

    comment: Optional[str]

    msg: Optional[str]





TestResult.__new__.__defaults__ = (None,) * 3  # type: ignore  # Hack for Python < 3.7

When I do passed_tc = TestResult("Passed"), I have the following error message

error:Too few arguments for "TestResult"

Anyone got an idea on how to tell mypy we can have optional arguments and avoid this error?

Assign the values that need default values with the desired default values. For example:

from typing import NamedTuple, Optional



class Test(NamedTuple):

    foo: str

    bar: Optional[str] = None

    qux: int = 100



t = Test("foo")

I've tested that this works at runtime for both Python 3.6 and 3.7, and confirmed it type-checks as expected using mypy 0.641.