Support strings being passed to grep

This also returns a nicer error if a Regex or String isn't passed.

lib/ring_logger.ex

@@ -127,8 +127,8 @@ defmodule RingLogger do
   * Options from `attach/1`
   * `:pager` - a function for printing log messages to the console. Defaults to `IO.binwrite/2`.
   """
-  @spec grep(Regex.t(), [client_option]) :: :ok | {:error, term()}
-  defdelegate grep(regex, opts \\ []), to: Autoclient
+  @spec grep(Regex.t() | String.t(), [client_option]) :: :ok | {:error, term()}
+  defdelegate grep(regex_or_string, opts \\ []), to: Autoclient
 
   @doc """
   Helper method for formatting log messages per the current client's

lib/ring_logger/autoclient.ex

@@ -60,10 +60,10 @@ defmodule RingLogger.Autoclient do
   @doc """
   Run a regular expression on each entry in the log and print out the matchers.
   """
-  def grep(regex, opts \\ []) do
+  def grep(regex_or_string, opts \\ []) do
     with :ok <- check_server_started(),
          pid <- maybe_create_client(opts),
-         do: Client.grep(pid, regex, opts)
+         do: Client.grep(pid, regex_or_string, opts)
   end
 
   @doc """

lib/ring_logger/client.ex

@@ -119,14 +119,26 @@ defmodule RingLogger.Client do
 
   * `:pager` - an optional 2-arity function that takes an IO device and what to print
   """
-  @spec grep(GenServer.server(), Regex.t(), keyword()) :: :ok | {:error, term()}
-  def grep(client_pid, regex, opts \\ []) do
+  @spec grep(GenServer.server(), String.t() | Regex.t(), keyword()) :: :ok | {:error, term()}
+  def grep(client_pid, regex_or_string, opts \\ [])
+
+  def grep(client_pid, regex_string, opts) when is_binary(regex_string) do
+    with {:ok, regex} <- Regex.compile(regex_string) do
+      grep(client_pid, regex, opts)
+    end
+  end
+
+  def grep(client_pid, %Regex{} = regex, opts) do
     {io, to_print} = GenServer.call(client_pid, {:grep, regex})
 
     pager = Keyword.get(opts, :pager, &IO.binwrite/2)
     pager.(io, to_print)
   end
 
+  def grep(_client_pid, _regex, _opts) do
+    {:error, :invalid_regex}
+  end
+
   def init(config) do
     state = %State{
       io: Keyword.get(config, :io, :stdio),

test/ring_logger_test.exs

@@ -128,6 +128,22 @@ defmodule RingLoggerTest do
     assert message =~ "[debug] Hello, world"
   end
 
+  test "can grep using a string", %{io: io} do
+    :ok = RingLogger.attach(io: io)
+
+    io
+    |> handshake_log(:debug, "Hello")
+    |> handshake_log(:debug, "World")
+
+    RingLogger.grep("H..lo", io: io)
+    assert_receive {:io, message}
+    assert message =~ "[debug] Hello"
+  end
+
+  test "invalid regex returns error", %{io: io} do
+    assert {:error, _} = RingLogger.grep(5, io: io)
+  end
+
   test "can next the log", %{io: io} do
     :ok = RingLogger.attach(io: io)
     handshake_log(io, :debug, "Hello")