Make Mix.Utils.Underscore accept .'s and empty args

Author: jwarwick

lib/mix/lib/mix/utils.ex

@@ -194,6 +194,8 @@ defmodule Mix.Utils do
     underscore(rest)
   end
 
+  def underscore(""), do: ""
+
   def underscore(<<h, t :: binary>>) do
     <<to_lower_char(h)>> <> do_underscore(t, h)
   end
@@ -210,6 +212,12 @@ defmodule Mix.Utils do
     <<?_>> <> do_underscore(t, ?-)
   end
 
+  defp do_underscore(<< "..", t :: binary>>, _) do
+    <<"..">> <> underscore(t)
+  end
+
+  defp do_underscore(<<?.>>, _), do: <<?.>>
+
   defp do_underscore(<<?., t :: binary>>, _) do
     <<?/>> <> underscore(t)
   end

lib/mix/test/mix/utils_test.exs

@@ -52,6 +52,10 @@ defmodule Mix.UtilsTest do
     assert Mix.Utils.underscore("FoBaZa") == "fo_ba_za"
     assert Mix.Utils.underscore("Foo.Bar") == "foo/bar"
     assert Mix.Utils.underscore(Foo.Bar) == "foo/bar"
+    assert Mix.Utils.underscore("") == ""
+    assert Mix.Utils.underscore("..") == ".."
+    assert Mix.Utils.underscore("/..") == "/.."
+    assert Mix.Utils.underscore("foo/../bar") == "foo/../bar"
   end
 
   test :camelize do