Correct doc and error message for File.cp!/3

Author: lexmag

lib/elixir/lib/file.ex

@@ -480,14 +480,14 @@ defmodule File do
 
   @doc """
   The same as `cp/3`, but raises `File.CopyError` if it fails.
-  Returns the list of copied files otherwise.
+  Returns `:ok` otherwise.
   """
   @spec cp!(Path.t, Path.t, (Path.t, Path.t -> boolean)) :: :ok | no_return
   def cp!(source, destination, callback \\ fn(_, _) -> true end) do
     case cp(source, destination, callback) do
       :ok -> :ok
       {:error, reason} ->
-        raise File.CopyError, reason: reason, action: "copy recursively",
+        raise File.CopyError, reason: reason, action: "copy",
           source: IO.chardata_to_string(source), destination: IO.chardata_to_string(destination)
     end
   end

lib/elixir/test/elixir/file_test.exs

@@ -123,7 +123,7 @@ defmodule FileTest do
     test :cp_with_src_dir! do
       src   = fixture_path("cp_r")
       dest  = tmp_path("tmp.file")
-      assert_raise File.CopyError, "could not copy recursively from #{src} to #{dest}: " <>
+      assert_raise File.CopyError, "could not copy from #{src} to #{dest}: " <>
           "illegal operation on a directory", fn ->
         File.cp!(src, dest)
       end
@@ -883,7 +883,7 @@ defmodule FileTest do
     end
   end
 
-   test :lstat do
+  test :lstat do
     {:ok, info} = File.lstat(__ENV__.file)
     assert info.mtime
   end