Assertions Python Packages

pandera

A light-weight, flexible, and expressive statistical data testing library

asserts

Stand-alone Assertions for Python

grappa

Behavior-oriented, expressive, human-friendly Python assertion library for the 21st century

assertpy2

Fluent assertion library for Python with composable matchers, structural matching, and full type safety

fluentcheck

Fluent assertions for Python

mcp-assert

The testing standard for MCP servers. Lint (14 rules), test, and fuzz over real stdio/SSE/HTTP transport. 18 assertion types in YAML. Found 4,794 schema issues across 55 servers. Any language, no mocks, single binary.

assertionlib

A package for performing assertions and providing informative exception messages.

pytest-mcp-assert

The testing standard for MCP servers. Lint (14 rules), test, and fuzz over real stdio/SSE/HTTP transport. 18 assertion types in YAML. Found 4,794 schema issues across 55 servers. Any language, no mocks, single binary.

pyssertive

Fluent, chainable assertions for Django tests. Inspired by Laravel's elegant testing API.

sentienceapi

A verification-first runtime for AI web agents — with Jest-style assertions and token-efficient snapshots

pytest-llm-assert

Natural language assertions for pytest using LLMs

business-use-core

Track, validate, and visualize business flows in production applications.

business-use

Track, validate, and visualize business flows in production applications.

grappa-http

HTTP assertion plugin for grappa

conditions-py

Conditions libary for Python 3+

predicate-sdk

A verification-first runtime for AI web agents — with Jest-style assertions and token-efficient snapshots

predicate-runtime

A verification-first runtime for AI web agents — with Jest-style assertions and token-efficient snapshots

sentience-python

A verification-first runtime for AI web agents — with Jest-style assertions and token-efficient snapshots

predicatelabs

A verification-first runtime for AI web agents — with Jest-style assertions and token-efficient snapshots

assertify

Simple, Flexible, and Extendable python3.6+ library for boolean expressions, assertions, and verifications.

ml-assert

A declarative assertion library for validating ML data and model behavior.

flexible-matchers

Lightweight, zero-dependency mock assertion helpers with flexible numeric and string matching

fluent-assertions

Fluent API for assertions supporting pytest, designed with simplicity and ease of use in mind.

sql-guard

A small package for data quality rules using SQL