pytest-httpchain-templates 0.8.0

Templating support for pytest-httpchain

pytest-httpchain-templates

The {{ expression }} template engine for pytest-httpchain.

This package evaluates template expressions and walks them recursively through strings, dicts, lists, Pydantic models, and SimpleNamespace objects against a context. A value that is a single {{ ... }} expression preserves its type (walk("{{ 42 }}", {}) returns the int 42), while mixed content interpolates into a string. Expressions are evaluated with simpleeval and a curated set of built-ins (type conversions, len/min/max/sum, range, uuid4(), env(), and the context helpers get() / exists()). Note that scenario files are treated as trusted input — simpleeval blocks accidental footguns but is not a hardened sandbox, so templates can run arbitrary Python by design.

Role in the workspace

pytest-httpchain shares a key-value context across the stages of a scenario. When a stage runs, the plugin walks its request model through this engine, substituting saved values, fixtures, parametrize parameters, and substitution variables before the HTTP request is sent. It is published separately so the evaluation logic can be reused and tested in isolation.

Usage

from pytest_httpchain_templates.substitution import walk
from pytest_httpchain_templates.exceptions import TemplatesError

try:
    walk("{{ name }}", {"name": "Alice"})            # "Alice"
    walk("{{ [x * 2 for x in items] }}", {"items": [1, 2]})  # [2, 4]
    walk("{{ get('missing', 'default') }}", {})      # "default"
except TemplatesError as e:
    print(f"template error: {e}")

Links

• Documentation: https://aeresov.github.io/pytest-httpchain/
• Source and issues: https://github.com/aeresov/pytest-httpchain