behave-playwright

BDD web testing with Behave and Playwright — reusable Gherkin step definitions plus browser lifecycle hooks, so you write features, not boilerplate.

Feature: Login
  Scenario: Successful login
    Given I navigate to "/login"
    When I fill "Email" with "user@test.com"
    And I fill "Password" with "secret"
    And I click "Sign in"
    Then I should see "Welcome back"

Quickstart

pip install behave-playwright
playwright install          # one-time browser download
behave-playwright init      # scaffold behave.ini + features/
behave

init creates (use -d DIR to pick the target, --force to overwrite):

behave.ini
features/
├── environment.py                  # from behave_playwright.environment import *
├── steps/behave_playwright_steps.py  # import behave_playwright.steps
└── example.feature

Already have a behave project? Add the two imports yourself:

# features/environment.py
from behave_playwright.environment import *  # noqa: F401,F403

# features/steps/behave_playwright_steps.py
import behave_playwright.steps  # noqa: F401

That's it — one browser per run, fresh context + page per scenario, screenshot captured and attached on failure.

The context

context (behave's) is wired automatically per scenario:

Custom hooks

The lifecycle hooks are plain functions — delegate when you need your own setup:

# features/environment.py
from behave_playwright import environment as bp


def before_all(context):
    my_app.start()
    context.config.userdata.setdefault("base_url", "http://localhost:8000")
    bp.before_all(context)


def before_scenario(context, scenario):
    my_app.reset_db()
    bp.before_scenario(context, scenario)


def after_scenario(context, scenario):
    bp.after_scenario(context, scenario)


def after_all(context):
    bp.after_all(context)
    my_app.stop()

Steps register on import — import behave_playwright.steps in a step file, or behave_playwright.steps.use_steps() from environment.py to make it explicit.

Element targeting

Steps take a plain string and resolve it the way Playwright recommends — accessible selectors first:

1. get_by_role (accessible name)
2. get_by_label / get_by_placeholder (form fields)
3. get_by_text
4. get_by_test_id
5. CSS selector

Force a strategy with a prefix:

Step catalog

Navigation

Given I navigate to "/login"        # aliases: I go to, I open — resolves against base_url
When I go back / forward
When I reload the page              # alias: I refresh the page

Interaction

When I click "Sign in"              # aliases: click on, double click, right click, hover
When I fill "Email" with "a@b.c"    # aliases: fill in ... with, I enter "x" in/into "Email"
When I type "hello" in "Search"     # per-key events (fill is instant)
When I fill the form:               # data table: columns | field | value |
  | field    | value   |
  | Email    | a@b.c   |
When I clear "Email"
When I select "Banana" from "Fruit" # by label; alias: in
When I check "Accept terms" / I uncheck "Accept terms"
When I press the "Enter" key        # or: I press "Enter" on/in "Search"
When I upload the file "data.csv" to "Upload"
When I scroll to "css=#footer"
When I drag "css=#src" to "css=#dst"
When I take a screenshot / I take a screenshot of "css=#modal"

Assertions (auto-retrying — Playwright expect under the hood)

Then I should see "Welcome back" / I should not see "Error"
Then the "css=.modal" element should be visible / hidden / enabled / disabled / checked / not checked
Then I should see the "css=.modal" element
Then the url should be "/dashboard" / the url should contain "dashboard"
Then the title should be "Home" / the title should contain "Hom"
Then I should see 3 "css=.item" elements
Then the "css=.banner" element should contain "Sale ends today"   # substring
Then the "css=.banner" element should have text "Sale: 50%"       # exact
Then the "css=.logo" element should have attribute "src" with value "/logo.png"
Then the "Email" field should have value "user@test.com"
Then the "session" cookie should exist / have value "abc123"
Then there should be no console errors / except "favicon"
Then the file "report.pdf" was downloaded

Waits — Playwright auto-waits everywhere; these exist for when an explicit wait is the honest expression of intent

When I wait for "css=.spinner" to be hidden   # also: to disappear / the "x" element
When I wait for text "Loaded"                 # also: for the text "Loaded"
When I wait for the page to load / I wait for navigation
When I wait for the network to be idle
When I wait 2 seconds                         # only wait_for_timeout in the lib

Network — interception patterns: glob (**/api/*, * within a segment, ** across), bare path (/api/x → **/api/x), or /regex/. Intercept steps register routes — use them before navigation.

Given I intercept "/api/users" and return:     # docstring is required
  """[{"name": "Ada"}]"""                       # served as application/json
When I intercept "**/api/health" and respond with status 503:
  """backend is down"""                         # optional docstring body
When I intercept "**/analytics" and abort
Then a request was made to "**/api/login"       # waits up to `timeout` for it
Then a "POST" request was made to "**/api/login"

Session — device emulation, tracing, storage state (these recreate browser_context + page)

When I emulate device "iPhone 12"
When I enable tracing          # on failure → <traces_dir>/<scenario>.trace.zip (view: playwright show-trace)
Given I am logged in as "ada"  # loads auth/ada.json (convention)
When I save the storage state to "auth/ada.json"
Given I use the storage state "auth/ada.json"

Tabs, frames, dialogs, downloads

When I open a new tab with "/docs"
When I click "Help" in a new tab       # popup capture + switch
When I switch to tab 2                    # 1-based
When I close the current tab
When I switch to the "payment" iframe  # steps now act on the frame…
When I switch back to the main frame   # …until you switch back
When I accept the next dialog          # must precede the action that opens it
When I dismiss the next dialog / I answer the next dialog with "42"
When I click "Export" and download the file  # saved to downloads_dir

Configuration

Via behave -D key=value, behave.ini userdata, or BEHAVE_PW_* env vars:

behave -D browser=firefox -D headless=false -D base_url=http://localhost:8000

Keys can also be namespaced to avoid collisions with other -D values: -D behave_playwright.browser=firefox works too.

Examples

• examples/saucedemo — a complete project against the classic saucedemo.com test site: login, inventory, cart flow and network mocking, plus a custom step composed via execute_steps. cd examples/saucedemo && behave (needs internet).
• examples/playground — a self-contained testbed: local app + API covering every feature (forms, tabs, iframes, dialogs, downloads, storage state, device emulation, network, console errors, artifacts). cd examples/playground && behave — no internet needed.

Custom steps and the page object

The bundled steps cover the common cases; write your own on top of context.page:

@then("the cart badge shows {count:d} items")
def step_cart_badge(context, count):
    expect(context.page.locator(".cart-badge")).to_have_text(str(count))

If a step creates a page itself (custom popup handling, extra tabs), call wire_page(context, page) from behave_playwright.environment so it inherits timeouts and request/console captures.

Or compose bundled steps with execute_steps:

@given("I am logged in")
def step_logged_in(context):
    context.execute_steps("""
        Given I navigate to "/"
        When I fill "Email" with "a@b.c"
        And I fill "Password" with "secret"
        And I click "Sign in"
        """)

Philosophy

• Auto-wait by default — no sleep/wait_for_timeout except the explicit I wait N seconds step. If a step is flaky, the fix is a better locator, not a longer sleep.
• Sync API only — behave is synchronous; Playwright's sync API is the right fit.
• Steps + hooks, not a runner — behave stays the runner; this library removes the boilerplate.

Development

pip install -e ".[dev]"
pytest          # unit + integration tests (real Chromium + local server)
ruff check      # lint
mypy            # type check
behave --dry-run  # validate step registration

See CONTRIBUTING.md for the full contributor workflow.

License

MIT — see LICENSE. Security reports: SECURITY.md.