Credentials

Credentials is a virtual WebAuthn authenticator scoped to a BrowserContext. It lets tests register passkeys and answer navigator.credentials.create() / navigator.credentials.get() ceremonies in the page, without a real authenticator or hardware security key.

There are two common ways to use it:

Usage: seed a known credential

context = browser.new_context

# A passkey your backend already provisioned for a test user.
context.credentials.create(
  "example.com",
  id: known_credential_id, # base64url
  userHandle: known_user_handle, # base64url
  privateKey: known_private_key, # base64url PKCS#8 (DER)
  publicKey: known_public_key, # base64url SPKI (DER)
)
context.credentials.install

page = context.new_page
page.goto("https://example.com/login")
# The page's navigator.credentials.get() is answered with the seeded passkey.

Usage: capture a passkey, then reuse it

# setup test: let the app register a passkey, then save it.
context = browser.new_context
context.credentials.install

page = context.new_page
page.goto("https://example.com/register")
page.get_by_role("button", name: "Create a passkey").click

# Read back the passkey the page registered - it includes the private key.
credential = context.credentials.get(rpId: "example.com").first
File.write("playwright/.auth/passkey.json", JSON.generate(credential))

# later test: seed the captured passkey so the app starts already enrolled.
credential = JSON.parse(File.read("playwright/.auth/passkey.json"))
context = browser.new_context
context.credentials.create(
  credential["rpId"],
  id: credential["id"],
  userHandle: credential["userHandle"],
  privateKey: credential["privateKey"],
  publicKey: credential["publicKey"],
)
context.credentials.install

page = context.new_page
page.goto("https://example.com/login")
# navigator.credentials.get() resolves the captured passkey - already signed in.

Defaults

install

def install

Installs the virtual WebAuthn authenticator into the context, overriding navigator.credentials.create() and navigator.credentials.get() in all current and future pages. Call this before the page first touches navigator.credentials.

Required: until Credentials#install is called, no interception is in place and the page sees the platform's native (or absent) WebAuthn behaviour. Seeding credentials with Credentials#create without installing populates the authenticator, but the page will never see those credentials.

create

def create(
      rpId,
      id: nil,
      privateKey: nil,
      publicKey: nil,
      userHandle: nil)

Seeds a virtual WebAuthn credential and returns it.

With only rpId, generates a fresh ECDSA P-256 keypair, credential id and user handle. The seeded credential is discoverable (resident), so the page can resolve it from both username-then-passkey and usernameless passkey flows. The returned object carries the private and public keys, so it can be persisted to disk and re-seeded in a later test.

To import a known credential, supply all four of id, userHandle, privateKey and publicKey together.

Call Credentials#install before navigating to a page that uses WebAuthn.

delete

def delete(id)

Removes a credential from the authenticator by its id. Works for any credential currently held — both those seeded with Credentials#create and those the page registered itself by calling navigator.credentials.create().

get

def get(id: nil, rpId: nil)

Returns every credential currently held by the authenticator, optionally filtered by rpId or id. This includes both credentials seeded with Credentials#create and credentials the page registered itself by calling navigator.credentials.create().

Each returned credential includes its private and public keys, so a passkey the app just registered can be saved and re-seeded into a later test with Credentials#create — see the second example in the class overview.