The checks library uses a few custom type annotations to make functions a bit more readable, or to provide additional information about parameters. This document will explain what they mean.
Checks = TypeVar("Checks", bound=Union["Check", Iterable["Check"]])Checks is used to indicate that a parameter can be a variable amount of Checks. This also allows lists, tuples, maps and generator expressions to be passed into this function.
The examples below use the all_of utility function to show what this is capable of.
html = HtmlSuite(content)
body = html.element("body")
# One argument:
# - <body> exists
all_of(body.exists())
# Multiple arguments:
# - <body> exists
# - <body> contains a <div>
all_of(body.exists(), body.has_child("div"))
# Using map() to quickly check if the body only contains <div> elements
all_of(map(lambda c: c.has_tag("div"), body.get_children()))
# Using a generator expression to check if the body only contains <div> elements
all_of(c.has_tag("div") for c in body.get_children())The use of this specific type also removes the need for unnecessary spread operators (*) and list casts, which allows for slightly cleaner code.
# Before:
all_of(*[c.exists() for c in elements])
# After:
all_of(c.exists() for c in elements)Emmet = TypeVar("Emmet", bound=str)The Emmet type suggests you can use Emmet Syntax on this parameter. You can not create an instance of this class, and these parameters still take a string.
def function(arg: Emmet): ...
# Emmet parameters are equal to strings
function("body>table>#some_id")In most cases, the type will be Union[str, Emmet]. This is to show that you can also use other means (eg. names of HTML tags, ...) instead of only Emmet Syntax.