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Here’s an application of “test smarter, not harder”, as per Luke Plant’s post. I came up with this recently whilst working on my client Silvr’s project, and I’m pretty proud of it. It should apply to any project using Django’s admin.
Sometimes you want to download a whole website so you have a local copy that you can browse offline. When programming, this is often useful for documentation that sites that do not provide downloadable versions, and are not available in offline tools like DevDocs.
Your Django project’s startup time impacts how smooth it is to work with. Django has to restart your project every time you run a management command and when runserver reloads. This involves importing all your apps, and thus all the modules that they import.
Python 3.11 only made one change to unittest, but it’s a good one: context manager methods. These methods can simplify setup and teardown logic in many cases, such as dynamic use of unittest.mock.
Take this code, which prints a shruggy man:
Sometimes code uses boolean checks on variables that can only be true. This is normally a sign of a mistake, either in the type hints or the implementation. Mypy has an optional check that can find such problematic boolean usage with its truthy-bool error code.
The original type hint proposal, PEP 484, initially allowed implicit optional types in function signatures. That is, a parameter with a default value of None would have its type automatically interpreted as optional. For example, this signature:
As type hints have evolved, Python has added simpler, more succinct syntaxes. But you still need to know the older forms, since Mypy uses them when reporting types.
Exhaustiveness checking is a very handy type checker feature. It ensures that all possible types of a variable are handled. If your code changes to add another possible type, you can guarantee that exhaustiveness-checked code paths handle the new case.
Python has no syntax to add type hints to lambdas, but that doesn’t mean you can’t use them in type-checked code. In this post we’ll look at how Mypy can infer the types for lambdas, based on where they’re used.