MyPy

Mypy is a static type checker for Python. If you sprinkle your code with type annotations, mypy can type check your code and find common bugs. As mypy is a static analyzer or a lint-like tool, the type annotations are just hints for mypy and don’t interfere when running your program. You run your program with a standard Python interpreter, and the annotations are treated effectively as comments.

For further information visit https://mypy.readthedocs.io/en/stable/introduction.html

Installation

$ poetry add mypy --dev

Configuration

Add the following in setup.cfg:

[mypy]
ignore_missing_imports = true
disallow_untyped_defs = true
warn_redundant_casts = true
warn_unreachable = true
show_error_codes = true
pretty = true

Usage

$ mypy python_lifecycle_training tests
MyPy Output

Resolution

from numbers import Real


def add(a: Real, b: Real) -> Real:
    return a + b

def test_version() -> None:
    assert __version__ == "0.1.0"

Add a badge

Checked with mypy 
.. image:: http://www.mypy-lang.org/static/mypy_badge.svg
    :target: http://mypy-lang.org/
    :alt: Checked with mypy

Next Step

To move on to the next step commit or stash your changes then checkout to the branch init/pre-commit

$ git stash
$ git checkout init/pre-commit

Uninstall

$ poetry remove mypy --dev