Playwright rs usage

Using playwright-rs

Rust bindings for Microsoft Playwright. This crate is a thin JSON-RPC client to the upstream Playwright server, so the API mirrors playwright-python / java / .NET semantics. When unsure about a method's behavior, the upstream Playwright docs are the authoritative reference.

Drift discipline. The canonical API tour lives in the crate-level rustdoc at https://docs.rs/playwright-rs — that's compile-checked against the actual code. This skill is the "what to reach for, what to avoid" overlay: durable conventions, not a method-by-method reference. The one Rust code block below is compile-checked by cargo xtask verify-agent-docs; the rest is prose that ages well because it talks in concepts (auto-wait, builder pattern) rather than specific method names.

Object model

Playwright            start here — Playwright::launch().await?
  └── BrowserType     .chromium() / .firefox() / .webkit()
        └── Browser   .launch().await? → owns the browser process
              └── BrowserContext       isolated cookies / storage
                    └── Page            one tab
                          └── Locator   selector with auto-wait

Locator is the workhorse. Build with page.locator(...) or the semantic get_by_* helpers (get_by_role, get_by_text, etc. — see docs.rs for the full list) and chain action / assertion methods.

Conventions to follow

• Result<T> and async/await on tokio. One error type: playwright_rs::Error. Use ? to propagate.
• Builders / setters for option-heavy methods. goto, click, screenshot, fill, tracing().start, etc. take an Options struct. These are #[non_exhaustive] (so upstream option additions stay non-breaking) — struct literals won't compile. Construct with the type's builder() where it has one, otherwise chain setters off Default/new(): GetByRoleOptions::default().name("OK").exact(true), Cookie::new(name, value).domain("example.com"). The exact method names live on docs.rs; don't memorize them.
• Auto-wait + auto-retry. Locator-based actions wait until the element is actionable; expect() assertions retry until they hold or time out. Never insert tokio::time::sleep between an action and a check — that's a smell. If a wait feels necessary, you probably want expect(locator).to_be_visible().await or similar.
• locator!() macro for literal selectors. Compile-time validation catches typos and structural errors. Fall back to &str only for selectors computed at runtime.
• No reimplemented browser protocols. This crate is intentionally thin over the Playwright server. Anything you can't do via Playwright itself, you can't do here.

Minimal test skeleton

This block is compile-checked by cargo xtask verify-agent-docs — if the API drifts, the verifier fails:

use anyhow::Result;
use playwright_rs::{Playwright, locator, expect};

#[tokio::test]
async fn login_flow() -> Result<()> {
    let pw = Playwright::launch().await?;
    let browser = pw.chromium().launch().await?;
    let context = browser.new_context().await?;
    let page = context.new_page().await?;

    page.goto("https://example.com/login", None).await?;
    page.locator(locator!("input[name='user']")).fill("alice", None).await?;
    page.locator(locator!("input[name='pass']")).fill("hunter2", None).await?;
    page.locator(locator!("text=Sign in")).click(None).await?;

    expect(page.locator(locator!(".welcome"))).to_be_visible().await?;

    browser.close().await?;
    Ok(())
}

Capabilities worth reaching for

Concept-level pointers; the exact options live on docs.rs.

• Stable / redacted screenshots. ScreenshotOptions carries animations(Disabled) for flake-free shots (freeze CSS animations before capture) and mask/mask_color to overpaint dynamic or sensitive elements. Reach for animations(Disabled) whenever a screenshot races an animation.
• Context-level events. Beyond per-page handlers, BrowserContext observes activity across all its pages — on_download, on_page_load / on_page_close, on_frame_attached / _detached / _navigated — and Browser::on_context fires for each new context. Use these for multi-tab fixtures instead of wiring every page individually.
• HAR network capture. tracing().start_har(path, ..) / stop_har() records all network traffic to a HAR — inspect it in browser devtools or replay it deterministically with route_from_har. A sibling to trace capture.
• Typed page probes. page.evaluate::<R, T>(expr, arg) deserializes the JS return value straight into any serde Deserialize type — define a struct for the shape and skip manual parsing (None::<&()> for the no-argument case). evaluate_value (returns String) is only for one-off scalar probes; if you catch yourself returning delimited strings from JS and splitting them in Rust, switch to evaluate. Runnable walkthroughs: examples/evaluate_typed.rs and examples/canvas_pixels.rs (canvas pixel assertions for wasm/canvas frontends).
• Drags: Locator::drag_to covers everything, including canvas. It drives the real pointerdown → capture → pointermove → pointerup chain (works against setPointerCapture UIs), and DragToOptions::target_position — an offset from the target's top-left — turns it into "drag to a coordinate": pass the containing canvas/stage as the target. Prefer it over held-button Mouse::move_to sequences, which hang on headless Linux. Don't hand-roll synthetic PointerEvent dispatch via evaluate.
• External drag-and-drop. Locator::drop simulates dragging files or data in from outside the page (upload zones), distinct from drag_to, which drags one element onto another within the page.
• File System Access API flows. page.fake_file_system() installs an opt-in fake of showSaveFilePicker/showOpenFilePicker (native dialogs no automation tool can drive): seed opens with set_open_file, assert saves with last_saved_bytes(), control permission state. Don't hand-roll an add_init_script picker shim.
• Accessibility-tree assertions. expect_page(&page) .to_match_aria_snapshot(..) (and the locator form) guard the page's ARIA structure as a regression check; aria_snapshot can emit [box=..] bounding boxes for visual/agent reasoning.

Debugging failures with traces

Rust has no async Drop, so trace cleanup is explicit. The canonical pattern: capture the test result, run cleanup unconditionally, pass the trace path only on failure.

See examples/trace_on_failure.rs for the runnable end-to-end version — it's compiled by cargo check --examples so it can't silently rot.

To view a captured trace: playwright show-trace trace.zip. The viewer is language-agnostic — same UI JS / Python users see. The hosted version is at https://trace.playwright.dev.

Programmatic trace inspection

For CI bots, agent feedback loops, or any code that wants to read what happened in a trace without re-running the test, add the companion crate as a [dev-dependencies] entry: playwright-rs-trace = "0.1".

Use TraceReader::actions() to walk the reassembled action stream, TraceReader::network() for HTTP traffic. The crate's //! rustdoc on https://docs.rs/playwright-rs-trace has a runnable example.

Things that look like playwright-python but aren't quite

• No sync_playwright. Async only; everything awaits on tokio.
• Result, not exceptions. Use ? to propagate.
• No keyword arguments. Options come through Options structs with ..Default::default(), not name=value in method calls.
• No async Drop. Always close browsers / stop tracing explicitly in a cleanup block — don't rely on RAII for I/O.
• Locators are values, not lazy proxies. page.locator(...) returns a Locator you can .clone() and re-use cheaply.

Common pitfalls

• Manual sleeps before assertions. Use expect(..) and let it auto-retry.
• Closing the browser before tracing.stop() — traces are written on stop, so order matters: stop tracing first, then close.
• Hardcoding selectors as &str. Switch to locator!() for any selector you write as a literal.

References

• Full API: https://docs.rs/playwright-rs
• Runnable examples: https://github.com/padamson/playwright-rust/tree/main/crates/playwright/examples
• Upstream Playwright docs: https://playwright.dev/docs/api
• Trace format / parser: https://docs.rs/playwright-rs-trace
• locator!() macro: https://docs.rs/playwright-rs-macros