assertpy

library1.1pypypi✓ verified 35d ago

AssertPy is a simple assertion library for Python unit testing with a fluent API, inspired by AssertJ for Java. It allows for highly readable and chainable assertions. The current version is 1.1, and it has an active release cadence with frequent updates.

testing

github ↗package ↗

Install & Compatibility

Where this runs

No compatibility data collected yet for this library.

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

The primary entry point for all fluent assertions.

from assertpy import assert_that

Used as a context manager to collect multiple assertion failures without halting execution immediately.

from assertpy import soft_assertions

Renamed from `assert_soft` in v0.10; logs warnings instead of raising an AssertionError.

from assertpy import assert_warn

This quickstart demonstrates basic chained assertions using `assert_that` and shows how to use `soft_assertions` as a context manager to collect multiple failures before raising a single `AssertionError` at the end of the block.

from assertpy import assert_that, soft_assertions def test_basic_assertions(): assert_that(1 + 2).is_equal_to(3) assert_that('foobar').is_length(6).starts_with('foo').ends_with('bar') assert_that(['a', 'b', 'c']).contains('a').does_not_contain('x') print('Basic assertions passed.') def test_soft_assertions(): with soft_assertions(): assert_that(1).is_equal_to(2) # This will fail assert_that('hello').is_length(10) # This will also fail print('Soft assertions completed. Failures (if any) are collected.') test_basic_assertions() test_soft_assertions()

Debug

Known footguns

breakingThe `assert_soft()` function was renamed to `assert_warn()`.

breakingThe `extract()` helper function was renamed to `extracting()`.

gotchaOlder versions of AssertPy supported Python 2.x, but modern versions are Python 3.x only. Specific older Python 3 versions (e.g., 3.3, 2.6) have also been dropped over time.

gotchaWhen using `matches()` for regular expression assertions, be aware that it performs a partial match (like `re.match`). For exact full string matches, include anchors (e.g., `^...$`) in your regex pattern.

gotchaFor `dict` equality comparisons with `is_equal_to()`, you can control which keys are included or ignored. If not specified, all keys are compared.

gotchaSnapshot testing (`.snapshot()`) requires Python 3.x and saves artifacts to disk (e.g., `__snapshots` directory by default). These artifacts should be committed to version control.

Upgrade

Version history

Breaking-change detection hasn't run for this library yet.

Audit

Security & dependencies

CVE tracking and dependency tree are planned for a later release.

Agent activity

0 hits · last 30 days

No traffic data recorded yet.

Resources

githubhttps://github.com/assertpy/assertpy ↗

packagehttps://pypi.org/project/assertpy/ ↗