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anys 0.3.0

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anys provides matchers for pytest-style assertions. What’s a “matcher,”
you say? Well, say you’re writing a unit test and you want to assert that a
given object contains the correct values. Normally, you’d just write:
assert foo == {
"widgets": 42,
"name": "Alice",
"subfoo": {
"created_at": "2021-06-24T18:41:59Z",
"name": "Bob",
"widgets": 23,
}
}
But wait! What if the value of foo["subfoo"]["created_at"] can’t be
determined in advance, but you still need to check that it’s a valid timestamp?
You’d have to compare everything in foo other than that one field to the
expected values and then separately check the timestamp field for validity.
This is where matchers come in: they’re magic objects that compare equal to any
& all values that meet given criteria. For the case above, anys allows you
to just write:
from anys import ANY_DATETIME_STR

assert foo == {
"widgets": 42,
"name": "Alice",
"subfoo": {
"created_at": ANY_DATETIME_STR,
"name": "Bob",
"widgets": 23,
}
}
and the assertion will do what you mean.

Installation
anys requires Python 3.7 or higher. Just use pip
for Python 3 (You have pip, right?) to install it:
python3 -m pip install anys

API
anys provides the following classes & constants for matching against values
meeting certain criteria. Matching is performed by comparing a value against
an anys matcher with ==, either directly or as a result of comparing
two larger structures with ==.
If a comparison raises a TypeError or ValueError (say, because you
evaluated 42 == AnyMatch(r'\d+'), which tries to match a regex against an
integer), the exception is suppressed, and the comparison evaluates to
False; all other exceptions are propagated out.
anys matchers can be combined using the & operator to produce new
matchers that require both operands to succeed; for example, AnyGT(23) & AnyLT(42) will match any number between 23 and 42, exclusive, and nothing
else.
anys matchers can be combined using the | operator to produce new
matchers that require at least one of the operands to succeed; for example,
ANY_INT | ANY_STR will match any value that is an int or a str.

Classes
Note that, unless stated otherwise, anys class constructors cannot take
anys matchers as arguments.
AnyContains(key: Any, /)
A matcher that matches any value for which key in value is true. If
key is an anys matcher, value == AnyContains(key) will instead be
evaluated by iterating through the elements of value and checking whether
any match key.
AnyFullmatch(pattern: Union[AnyStr, re.Pattern[AnyStr]], /)
A matcher that matches any string s for which re.fullmatch(pattern, s)
succeeds
AnyFunc(func: Callable, /)
A matcher that matches any value x for which func(x) is true. If
func(x) raises a TypeError or ValueError, it will be suppressed,
and x == AnyFunc(func) will evaluate to False. All other exceptions
are propagated out.
AnyGE(bound: Any, /)
A matcher that matches any value greater than or equal to bound
AnyGT(bound: Any, /)
A matcher that matches any value greater than bound
AnyIn(iterable: Iterable, /)
A matcher that matches any value that equals or matches an element of
iterable (which may contain anys matchers). Note that, if iterable
is a string, only individual characters in the string will match; to match
substrings, use AnySubstr() instead.
AnyInstance(classinfo, /)
A matcher that matches any value that is an instance of classinfo.
classinfo can be either a type or a tuple of types (or, starting in Python
3.10, a Union of types).
A number of pre-composed AnyInstance() values are provided as constants for
your convenience; see “Constants” below.
AnyLE(bound: Any, /)
A matcher that matches any value less than or equal to bound
AnyLT(bound: Any, /)
A matcher that matches any value less than bound
AnyMatch(pattern: Union[AnyStr, re.Pattern[AnyStr]], /)
A matcher that matches any string s for which re.match(pattern, s)
succeeds
AnySearch(pattern: Union[AnyStr, re.Pattern[AnyStr]], /)
A matcher that matches any string s for which re.search(pattern, s)
succeeds
AnySubstr(s: AnyStr, /)
A matcher that matches any substring of s
AnyWithAttrs(mapping: Mapping, /)
A matcher that matches any object obj such that getattr(obj, k) == v
for all k,v in mapping.items().
The values (but not the keys) of mapping can be anys matchers.
AnyWithEntries(mapping: Mapping, /)
A matcher that matches any object obj such that obj[k] == v for all
k,v in mapping.items().
The values (but not the keys) of mapping can be anys matchers.
Maybe(arg: Any, /)
A matcher that matches None and any value that equals or matches arg
(which can be an anys matcher)
Not(arg: Any, /)
A matcher that matches anything that does not equal or match arg (which can
be an anys matcher)

Constants
The following constants match values of the given type:

ANY_BOOL
ANY_BYTES
ANY_COMPLEX
ANY_DATE — Matches date instances. You may not be aware, but
datetime is a subclass of date, and so this also matches
datetimes. If you only want to match actual dates, use
ANY_STRICT_DATE.
ANY_DATETIME
ANY_DICT
ANY_FLOAT
ANY_INT
ANY_ITERABLE
ANY_ITERATOR
ANY_LIST
ANY_MAPPING
ANY_NUMBER
ANY_SEQUENCE
ANY_SET
ANY_STR
ANY_STRICT_DATE — Matches any instance of date that is not an
instance of datetime
ANY_TUPLE

The following constants match aware or naïve datetime or time
values:

ANY_AWARE_DATETIME
ANY_AWARE_TIME
ANY_NAIVE_DATETIME
ANY_NAIVE_TIME

The following constants match ISO 8601-style date, time, & datetime strings.
“Aware” matchers require timezone information, while “naïve” matchers forbid
it.

ANY_AWARE_DATETIME_STR
ANY_AWARE_TIME_STR
ANY_DATETIME_STR
ANY_DATE_STR
ANY_NAIVE_DATETIME_STR
ANY_NAIVE_TIME_STR
ANY_TIME_STR

Other constants:

ANY_FALSY — Matches anything considered false
ANY_TRUTHY — Matches anything considered true

Note: If you’re after a matcher that matches absolutely everything, Python
already provides that as the unittest.mock.ANY constant.

Caveat: Custom Classes
When a well-behaved class defines an __eq__ method, it will only test
against values of the same class, returning NotImplemented for other types,
[1] which signals Python to evaluate x == y by instead calling y’s
__eq__ method. Thus, when comparing an anys matcher against an
instance of a well-behaved class, the matcher can be on either the left or the
right of the ==. All of the classes in the Python standard library are
well-behaved, as are classes that don’t define __eq__ methods, but some
custom classes in third-party code are not well-behaved. In order to
successfully compare an anys matcher against an ill-behaved class, the
matcher must be on the left side of the == operator; if it is on the
right, only the custom class’s __eq__ method will be consulted, which
usually means that the comparison will always evaluate to false.

[1]
In order to work their magic, anys matchers do not follow this rule,
and so they are not well-behaved. “Do as I say, not as I do,” as they
say.