# Capability matrix

The table compares Fluffy's Phoenix and Playwright backends within the
boundaries described below.

- **equivalent** — matching behavior verified against Playwright;
- **structural subset** — supports HTML-represented state, with browser-only
  behavior excluded;
- **-** — unavailable or not applicable.

<!-- capability-matrix:start -->
| Feature | Phoenix | Playwright |
| --- | --- | --- |
| Documented CSS locator subset | equivalent | equivalent |
| Text, label, and attribute locators | equivalent | equivalent |
| Structural role and accessible-name subset | structural subset | equivalent |
| DOM assertions and strictness | equivalent | equivalent |
| Page title assertions | equivalent | equivalent |
| Indeterminate checkbox/radio DOM property | - | equivalent |
| Structural element actions | structural subset | equivalent |
| Visits, reloads, links, redirects, cookies, and HTTP forms | equivalent | equivalent |
| Phoenix.HTML data-method/data-to actions | structural subset | equivalent |
| LiveView events, patches, navigation, and structural action retry | equivalent | equivalent |
| LiveView form-change delivery and timing | structural subset | equivalent |
| Declarative LiveView keyboard events | structural subset | equivalent |
| Supported mutable form state and ordered submission | equivalent | equivalent |
| Structural Enter implicit form submission | structural subset | equivalent |
| Native constraint validation | - | equivalent |
| Specialized scalar input values | structural subset | equivalent |
| Computed style, layout, and browser accessibility tree | - | equivalent |
| Downloads | equivalent | equivalent |
| Named pages and new tabs | - | equivalent |
| Dialogs and browser request/response events | - | equivalent |
| Active-page JavaScript evaluation | - | equivalent |
| JavaScript-owned DOM and default actions | - | equivalent |
| Native invalid, submit, and formdata event ordering | - | equivalent |
| Hard-wrapped textarea, object, and custom-element entries | - | equivalent |
| Per-test sessions, cleanup, and Ecto sandbox propagation | equivalent | equivalent |
| Regex URL matching | equivalent | equivalent |
| Structured path, query, and fragment URL matching | equivalent | equivalent |
| Typed file selection and supported upload lifecycle | equivalent | equivalent |
| Script-opened file chooser events | - | equivalent |
<!-- capability-matrix:end -->

## Boundaries

### When to choose Playwright

Use Playwright for computed style, layout, browser accessibility, native
validation, arbitrary JavaScript, and browser network events. Phoenix operates
on parsed HTML and mutable form state.

### LiveView timing and keyboard events

LiveView eagerly dispatches each applicable form-control `phx-change` and
ignores `phx-debounce`/`phx-throttle` scheduling. Use Playwright for delay,
blur-only delivery, coalescing, cancellation, and throttle suppression.

For Enter, Space, and Tab, LiveView dispatches the supported direct and window
`phx-keydown`/`phx-keyup` bindings, filters `phx-key`, preserves `phx-target`,
and orders events around the structural default action. Application-defined
LiveSocket metadata, modifiers and chords, repeats, browser timing, inline
listeners, and client-side `JS` commands remain Playwright-only.

### LiveView document and patch boundaries

LiveView locators and actions see the current `Phoenix.LiveViewTest.View`,
not the surrounding dead layout. Use `Phoenix.ConnTest` for initial
outer-layout HTML assertions or Playwright for full-document interactions.
LiveView `unwrap/2` receives only the View.

### Browser baseline

Fluffy verifies compatibility against pinned Chromium. Firefox and WebKit are
available through Playwright but are not covered by Fluffy's conformance suite.

### Phoenix.HTML actions and dialogs

For a Static or LiveView target with `data-confirm`, `click/2` ignores the
attribute and continues with the normal structural action. It does not create,
inspect, accept, or dismiss a browser dialog; use Playwright whenever the
prompt or its cancellation path is part of the assertion. Both in-process
drivers model the pinned Phoenix.HTML `data-method`/`data-to` hidden-form
action for plain elements, including links and buttons. Custom
`phoenix.link.click` listeners, cancellation, and competing LiveView actions
remain browser-only.

### Forms and files

Static and LiveView bypass native validation and retain specialized scalar
input values as supplied strings. Use Playwright for validation events and
blocking, browser sanitization/defaults, and custom or form-associated elements.

File selection supports bounded local paths and typed in-memory payloads,
ordered multiple selection, clearing, and ordinary multipart forms, including
empty-file entries. Managed LiveView uploads support validation, progress,
cancellation, replacement, auto-upload, and submission.

Native picker UI, external uploaders, directories, drag-and-drop, and arbitrary
`FileList` mutation are unsupported. `Event.file_chooser/2` requires Playwright
because application JavaScript opens the chooser.

### Native escape hatch

`Fluffy.unwrap/2` exposes driver-specific APIs: `Plug.Conn`,
`Phoenix.LiveViewTest.View`, or `Fluffy.Playwright.Handle`. Use the shared event
and page APIs for lifecycle operations. See
[Native escape hatch](usage.md#native-escape-hatch) for callback behavior.