Add specs to Plug.BasicAuth (#1181)

lib/plug/basic_auth.ex

@@ -92,7 +92,9 @@ defmodule Plug.BasicAuth do
  strings with only alphanumeric characters and space
 
  """
- def basic_auth(conn, options \\ []) do
+ @spec basic_auth(Plug.Conn.t(), [auth_option]) :: Plug.Conn.t()
+ when auth_option: {:username, String.t()} | {:password, String.t()} | {:realm, String.t()}
+ def basic_auth(%Plug.Conn{} = conn, options \\ []) when is_list(options) do
  username = Keyword.fetch!(options, :username)
  password = Keyword.fetch!(options, :password)
 
@@ -116,7 +118,8 @@ defmodule Plug.BasicAuth do
 
  See the module docs for examples.
  """
- def parse_basic_auth(conn) do
+ @spec parse_basic_auth(Plug.Conn.t()) :: {user :: String.t(), password :: String.t()} | :error
+ def parse_basic_auth(%Plug.Conn{} = conn) do
  with ["Basic " <> encoded_user_and_pass] <- get_req_header(conn, "authorization"),
  {:ok, decoded_user_and_pass} <- Base.decode64(encoded_user_and_pass),
  [user, pass] <- :binary.split(decoded_user_and_pass, ":") do
@@ -134,6 +137,7 @@ defmodule Plug.BasicAuth do
  put_req_header(conn, "authorization", encode_basic_auth("hello", "world"))
 
  """
+ @spec encode_basic_auth(String.t(), String.t()) :: String.t()
  def encode_basic_auth(user, pass) when is_binary(user) and is_binary(pass) do
  "Basic " <> Base.encode64("#{user}:#{pass}")
  end
@@ -150,8 +154,11 @@ defmodule Plug.BasicAuth do
  * `:realm` - the authentication realm. The value is not fully
  sanitized, so do not accept user input as the realm and use
  strings with only alphanumeric characters and space
+
  """
- def request_basic_auth(conn, options \\ []) when is_list(options) do
+ @spec request_basic_auth(Plug.Conn.t(), [option]) :: Plug.Conn.t()
+ when option: {:realm, String.t()}
+ def request_basic_auth(%Plug.Conn{} = conn, options \\ []) when is_list(options) do
  realm = Keyword.get(options, :realm, "Application")
  escaped_realm = String.replace(realm, "\"", "")