---
id: expects
version: "0.9.0"
license: Apache 2.0
license_treatment: permissive
maintenance: dormant
---

# expects — Expressive and extensible TDD/BDD assertion library for Python

License: permissive · Maintenance: dormant · Downloads: 208.8K/mo

## What it is and what it does

Expects is a TDD/BDD assertion library that provides a fluent, composable syntax for writing test expectations. Instead of traditional assert statements, you use an `expect()` function paired with matchers (like `be_empty`, `equal`, `have_key`) chained with `.to()` or `.not_to()` to express what you expect from your code. The library supports combining matchers with `&` (and) and `|` (or) operators, and you can define custom matchers to extend its behavior.

The package has no runtime dependencies, making it lightweight to install. However, it is dormant—the last release was 2018-10-25, and it carries classifiers for Python 2.7, 3.5, 3.6, and 3.7, which are all end-of-life. No updates or security patches have been released in 2850 days, so using it on modern Python versions is risky and unsupported.

Use it for:

- Writing readable BDD-style test assertions in test suites where fluent syntax improves clarity over raw assert statements.
- Defining custom matchers for domain-specific test assertions that are reusable across a test suite.
- Testing exception behavior with matchers like `raise_error` to verify that code fails as expected.
- Composing complex assertions on data structures (dicts, lists) using chainable matchers and logical operators.

## Worth the install?

AI-flagged interpretation of the facts above — verify before relying.

Expects is an assertion library for TDD/BDD that lets you write test expectations using a fluent, composable matcher syntax with support for custom matchers.

No. The package is dormant (last release 2018-10-25) and targets end-of-life Python versions (2.7, 3.5, 3.6, 3.7). Compatibility with later Python versions is unverified and likely broken. For modern TDD/BDD assertion libraries, consider actively maintained alternatives.

## Install

pip install expects
uv add expects
poetry add expects

## Installing expects

Before you install: Installation friction is high—the package is dormant (last release 2018-10-25, no updates in 2850 days) and carries classifiers for Python 2.7, 3.5, 3.6, and 3.7, making it a poor fit for modern Python environments. The repo is not archived but shows no active maintenance.

License in practice: Licensed under Apache 2.0 (permissive), so you can use it freely in commercial and open-source projects without restriction, though the dormant status means no legal updates or security patches are forthcoming.

Quickstart:

pip install expects

from expects import expect, be_empty, equal

expect([]).to(be_empty)
expect('Foo').to(equal('Foo'))

The package targets Python 2.7, 3.5, 3.6, and 3.7; compatibility with later Python versions is unverified.

Verify before relying:

- Whether the package actually works on Python versions released after 3.7.
- Whether custom matchers can be defined and composed as the description suggests in practice.
- Current test coverage and whether the built-in matchers cover common assertion patterns.

## Package facts

- License: Apache 2.0 (permissive)
- Python support: unspecified
- Install friction: high
- Maintenance: dormant
- Downloads: 208.8K/month (top 15,000 on PyPI)
- Known vulnerabilities: none known

## Tags

python assertion library, BDD testing matchers, TDD expectation syntax, fluent test assertions, custom matcher framework, expressive test expectations, python testing DSL, bdd-testing, assertion-library, dormant

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