---
id: robotframework-assertion-engine
version: "5.0.1"
license: Apache-2.0
license_treatment: permissive
maintenance: active
---

# robotframework-assertion-engine — Generic way to create meaningful and easy to use assertions for the Robot Framework libraries.

License: permissive · Maintenance: active · Downloads: 786.4K/mo

## What it is and what it does

The Assertion Engine is a utility library for Robot Framework that abstracts assertion logic into a reusable component. It was originally developed as part of the Browser library and extracted as a standalone tool for use by other Robot Framework library developers. The package provides a `verify_assertion` method that accepts a value, an assertion operator (such as `==`, `!=`, `>`, `*=`, regex `matches`, or custom Python `validate` expressions), and an expected value, then performs the validation and returns results or raises errors accordingly.

Library developers integrate this by calling `verify_assertion` within their keyword methods to perform inline assertions without reimplementing validation logic. The engine supports multiple assertion operators covering equality, comparison, substring matching, regex extraction with optional group capture (returning strings, tuples, or dictionaries), and custom Python expression evaluation. It also provides a formatter interface for preprocessing values (normalize spaces, strip, case insensitive) and allows custom error messages with optional prefixes.

Use it for:

- Developing Robot Framework libraries that need consistent, reusable assertion syntax across multiple keywords.
- Extracting and validating data from pages or APIs using regex groups and named capture groups.
- Implementing custom validation logic in Robot Framework keywords using Python expressions.
- Normalizing and comparing values with formatters like case-insensitive or whitespace-normalized matching.
- Building test libraries that support multiple assertion operators without duplicating validation code.

## Worth the install?

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

Provides a standardized assertion engine for Robot Framework libraries, enabling inline validation with operators like equality, comparison, regex matching, and custom Python expressions.

Yes, if you are developing Robot Framework libraries and want to standardize assertion behavior across keywords. The package is actively maintained, has no known vulnerabilities, uses a permissive license, and has low install friction. It is most valuable for library developers rather than end-user test writers, as it is a building block for other libraries.

## Install

pip install robotframework-assertion-engine
uv add robotframework-assertion-engine
poetry add robotframework-assertion-engine

## Installing robotframework-assertion-engine

Before you install: Low install friction with a pure Python wheel distribution. Active maintenance with a recent commit on 2026-08-10 and a release on 2026-06-04. Requires Python 3.10 or later.

License in practice: Licensed under Apache-2.0 (permissive), allowing use in commercial and proprietary projects with minimal restrictions.

Quickstart:

pip install robotframework-assertion-engine

from robotframework_assertion_engine import verify_assertion, AssertionOperator

value = "test string"
result = verify_assertion(value, AssertionOperator.EQUAL, "test string")

Requires Python 3.10 or later; depends on robotframework and robotframework-pythonlibcore.

Verify before relying:

- Whether the package is actively used in production Robot Framework libraries beyond the Browser library.
- Performance characteristics when handling large regex matches or complex validation chains.
- Availability of comprehensive documentation or examples beyond the GitHub repository.

## Package facts

- License: Apache-2.0 (permissive)
- Python support: supports_current
- Install friction: low
- Maintenance: active
- Downloads: 786.4K/month (top 15,000 on PyPI)
- Known vulnerabilities: none known

## Tags

robot framework assertions, robot framework validation, assertion operators, robot framework testing, inline assertions robot, robot framework library assertions, assertion engine, robot-framework, testing-library, assertion-framework

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