# 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. | Feature | Phoenix | Playwright | | --- | --- | --- | | Frame locators and traversal | - | equivalent | | 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 | | Focus, blur, and focus assertions | - | 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 | | Enter implicit form submission | - | 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 | | Browser history navigation | - | equivalent | | Browser cookie helpers and storage-state export | - | equivalent | | Hover, drag-and-drop, and sequential typing | - | equivalent | | Dialogs, frame navigation, 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 | ## 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. Even Phoenix checks structural visibility; see [Visibility and DOM presence](usage.md#visibility-and-dom-presence) for the distinction from browser rendering and DOM absence. ### LiveView timing and keyboard events LiveView eagerly dispatches each applicable form-control `phx-change` and ignores `phx-debounce`/`phx-throttle` scheduling, including `phx-debounce="blur"`. Phoenix does not model focus; its change delivery is independent of focus. Use Playwright for delay, blur-only delivery, coalescing, cancellation, and throttle suppression. `Fluffy.press/4` has a driver-specific contract: - **Static:** unsupported; raises `Fluffy.CapabilityError` for every key. - **LiveView:** passes the supplied key unchanged to LiveViewTest keydown/keyup handlers bound to the selected element. This includes window bindings on that element, without discovering handlers elsewhere in the document. LiveViewTest supplies event values and targeting. Fluffy does not apply `phx-key` filters, translate keys or modifier combinations, synthesize field values, or simulate focus movement, editing, activation, or implicit submission. An element with no keyboard binding raises. Callers supply the intended key value. - **Playwright:** native browser key presses, including default actions and Playwright modifier syntax. Filling contenteditable elements requires Playwright. Static and LiveView fill input and textarea controls; they do not emulate editing element text. ### Focus and client state `Fluffy.Playwright.focus/3`, `Fluffy.Playwright.blur/3`, and focus assertions require Playwright. Static and LiveView do not track or simulate focus. On a changed LiveView render, local text values adopt the rendered value, except during `phx-trigger-action` handoff. Unchanged document renders preserve local values. Changes are detected across the document, not per control, so an unrelated update can discard local text. Checkbox/radio state survives while the rendered `checked` attribute is unchanged. Selected options survive while the option signature is unchanged; files survive while the matched control remains a file input. Use Playwright for focused input protection and exact browser patch behavior. ### 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 `Fluffy.unwrap/2` receives only the View. ### Tabs, windows, and iframes The Playwright backend exposes page handles for browser tabs and popup windows. All public page-management helpers live in `Fluffy.Playwright` and reject Phoenix sessions. Phoenix retains one current document internally; use shared page URL, title, and status assertions to inspect it. `Fluffy.Playwright.new_page/1` returns a handle; `Fluffy.Playwright.switch_page/2` selects it for subsequent actions. Use [frame locators](usage.md#frames-playwright) to query iframe contents with Playwright. Page switching does not select an iframe, and frame locators do not change the active page. Static and LiveView can query the iframe element in their current markup, but do not load its `src` or parse its `srcdoc` as a child document. They do not flatten iframe contents into the parent document or ignore frame boundaries: executing a frame-traversing query raises `Fluffy.CapabilityError`. Visit the embedded route directly to test it independently with Phoenix; use Playwright to test the embedding behavior. See [Pages, popups, and frames](advanced-events.md#pages-popups-and-frames) for how pages, browser contexts, and frames relate. ### 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`, `Fluffy.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. Native reset-button behavior requires Playwright. Static and LiveView clicks do not restore form defaults or clear file selections. LiveView reset buttons with `phx-click` still dispatch their server event. 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. `Fluffy.Event.file_chooser/1` 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.