vedro-fn

A plugin for the Vedro framework that enables a functional-style syntax for defining Vedro scenarios.

(!) Starting with Vedro v1.14, the functional‑style scenario syntax is available directly in Vedro core. Use vedro-fn only if your project is on Vedro v1.13 or earlier, or if you need backward‑compatibility with older versions.

Installation

$ vedro plugin install vedro-fn

$ pip3 install vedro-fn

# ./vedro.cfg.py
import vedro
import vedro_fn


class Config(vedro.Config):
    class Plugins(vedro.Config.Plugins):
        class VedroFn(vedro_fn.VedroFn):
            enabled = True

Usage

Basic Example

import base64
from vedro_fn import scenario, given, when, then

@scenario()
def decode_base64_encoded_str():
    with given:
        encoded = "YmFuYW5h"

    with when:
        decoded = base64.b64decode(encoded)

    with then:
        assert decoded == b"banana"

To run scenarios, use:

$ vedro run

Using Scenario Decorators

Scenario decorators (such as @skip, @only, etc.) can be passed via an extended syntax:

import base64
from vedro import skip
from vedro_fn import scenario, given, when, then

@scenario[skip]()
def decode_base64_encoded_str():
    with given:
        encoded = "YmFuYW5h"

    with when:
        decoded = base64.b64decode(encoded)

    with then:
        assert decoded == b"banana"

Parametrization

You can also use Vedro’s built-in @params decorator with @scenario for parametrized scenarios:

import base64
from vedro import params
from vedro_fn import scenario, when, then

@scenario([
    params("YmFuYW5h", b"banana"),
    params("", b""),
])
def decode_base64_encoded_str(encoded, expected):
    with when:
        decoded = base64.b64decode(encoded)

    with then:
        assert decoded == expected

Async Example

Here’s an example of an asynchronous scenario:

from vedro_fn import scenario, when, then
from interfaces.api import fetch_users

@scenario()
async def fetch_users_from_api():
    with when:
        users = await fetch_users()

    with then:
        assert users == [
            {"id": 1, "name": "Bob"},
            {"id": 2, "name": "Alice"},
        ]