Jagreehal Executable Stories Pytest Story API

executable-stories-pytest — Story API

Setup

from executable_stories import story


def test_applies_discount_code():
    story.init("Applies discount code", tags=["checkout"], ticket="CART-42", covers=["src/checkout.py"])

    story.given("a cart with items totaling $100")
    cart = create_cart([{"name": "Shirt", "price": 100}])

    story.when("a 20% discount code is applied")
    apply_discount(cart, "SAVE20")

    story.then("the total is $80")
    assert cart.total == 80

    story.and_("the discount is shown in the summary")
    assert len(cart.discounts) == 1

File naming: test_*_story.py. Output is automatic via the pytest plugin — .executable-stories/raw-run.json is written after all tests. Override with EXECUTABLE_STORIES_OUTPUT env var.

Note: and_ has a trailing underscore because and is a Python keyword.

Core Patterns

Step markers with Auto-And conversion

First call to given(), when(), or then() renders the keyword as-is. Subsequent calls to the same keyword auto-convert to "And". Explicit and_() always renders "And". Explicit but() always renders "But" and never auto-converts.

def test_blocks_suspended_user_login():
    story.init("Blocks suspended user login")

    story.given("the user account exists")          # renders "Given"
    story.given("the account is suspended")          # renders "And" (auto-converted)
    story.when("the user submits valid credentials")
    story.then("the user sees an error message")
    story.but("the user is not logged in")           # renders "But" (always)
    story.but("no session is created")               # renders "But" (always)

Step aliases

AAA pattern: story.arrange() (Given), story.act() (When), story.assert_() (Then).

Additional: story.setup(), story.context() (Given), story.execute(), story.action() (When), story.verify() (Then).

Note: The Then alias is assert_() because assert is a Python keyword.

Doc entries attached to steps

def test_processes_payment():
    story.init("Processes payment")

    story.given("a valid payment request")
    story.json("Request payload", {"amount": 50, "currency": "USD"})
    story.kv("Gateway", "stripe")

    story.when("the payment is submitted")
    story.code("Response", '{ "status": "ok" }', lang="json")

    story.then("the order is confirmed")
    story.table("Order summary",
        columns=["Item", "Qty", "Price"],
        rows=[["Widget", "2", "$25"]],
    )
    story.link("API docs", "https://docs.example.com/payments")
    story.note("Payment processed in sandbox mode")

Embedded HTML

Embed generated HTML (charts, single-file reports, skill/agent output) in an always-sandboxed iframe in the report. Exactly one of path / url / content is required; optional title and height (number → px, string passed through; default 400px).

story.html(content=chart_html, title="Latency chart", height=600)
story.html(url="https://dash.example.com/run/42", height=600)
story.html(path="./reports/summary.html", title="Summary")

Source guidance: generated/ephemeral HTML (a skill writing to a temp dir) → pass content (captured now, survives temp-dir cleanup). Stable on-disk artifact → pass path (inlined at format time).

The embedded HTML must be self-contained (a single file). Local files are inlined as the iframe's srcdoc; relative references to sibling CSS/JS/images are not rewritten, so a multi-file report renders broken. Use a single-file/inline mode or pass markup via content. Directory bundling is planned.

Sandbox-safe contract: renders inside <iframe sandbox="allow-scripts"> (opaque origin, no allow-same-origin). CDN scripts (Tailwind, Mermaid) and inline DOM scripts work; localStorage/ sessionStorage/cookies throw SecurityError (and an unguarded access aborts the rest of that script block) — guard with try/catch or avoid. No window.top/parent access; no popups.

Inline docs via docs parameter

story.given("valid credentials", docs=[
    {"kind": "kv", "label": "username", "value": "alice", "phase": "runtime"},
    {"kind": "note", "text": "Password masked for security", "phase": "runtime"},
])

Step wrappers with timing

def test_fetches_user_profile():
    story.init("Fetches user profile")

    story.given("a registered user")

    profile = story.fn("When", "the profile is fetched", lambda: fetch_profile("user-123"))

    story.expect("the profile contains the correct name", lambda: (
        assert profile.name == "Alice"
    ))

fn and expect wrap a callable with automatic timing. Exceptions propagate after duration is recorded. Both return the callable's result.

Init options

story.init("My scenario",
    tags=["smoke", "auth"],
    ticket="AUTH-42",              # or ticket=["AUTH-42", "AUTH-43"]
    meta={"priority": "high"},
    trace_url_template="https://jaeger.example.com/trace/{traceId}",
)

Manual step timing

story.given("a step to time")
token = story.start_timer()
# ... work ...
story.end_timer(token)

Attachments

story.attach("debug.log", "text/plain", path="/tmp/debug.log")
story.attach("config", "application/json", body='{"key":"val"}', encoding="IDENTITY")

Common Mistakes

CRITICAL Missing story.init() before steps

Wrong:

def test_my_scenario():
    story.given("something")  # No context — steps are lost

Correct:

def test_my_scenario():
    story.init("My scenario")
    story.given("something")

story.init() creates the thread-local context. Without it, step calls have no effect.

Source: packages/executable-stories-pytest/src/executable_stories/_story_api.py

HIGH Using and or assert instead of and_ or assert_

Wrong:

story.and("also this")     # SyntaxError: 'and' is a Python keyword
story.assert("result")     # SyntaxError: 'assert' is a Python keyword

Correct:

story.and_("also this")    # Trailing underscore
story.assert_("result")    # Trailing underscore

Python keywords and and assert cannot be used as method names. The trailing underscore follows PEP 8 naming conventions for keyword conflicts.

Source: packages/executable-stories-pytest/src/executable_stories/_story_api.py

MEDIUM Parameterized scenarios with pytest.mark.parametrize

import pytest

@pytest.mark.parametrize("a,b,expected", [(1, 2, 3), (2, 3, 5)])
def test_addition(a, b, expected):
    story.init(f"Adding {a} and {b}")
    story.given(f"two numbers {a} and {b}")
    story.when("the numbers are added")
    result = a + b
    story.then(f"the result is {expected}")
    assert result == expected

Each parametrize iteration produces a separate scenario. Use f-strings in the scenario title so each has a distinct name.

Source: packages/executable-stories-pytest/src/executable_stories/_plugin.py

Source: jagreehal/executable-stories — distributed by TomeVault.