Ensure empty binaries are trimmed

Author: josevalim

lib/ecto/type.ex

@@ -1001,9 +1001,8 @@ defmodule Ecto.Type do
   defp same_duration(_), do: :error
 
   @doc false
-  def empty_trimmed?(value, type) do
-    is_binary(value) and type != :binary and String.trim_leading(value) == ""
-  end
+  def empty_trimmed?(value, :binary), do: value == ""
+  def empty_trimmed?(value, _type), do: is_binary(value) and String.trim_leading(value) == ""
 
   ## Adapter related
 

test/ecto/changeset_test.exs

@@ -222,11 +222,11 @@ defmodule Ecto.ChangesetTest do
   test "cast/4: with binary empty values" do
     # <<9>> is a control character which should not be empty_trimmed
     # for a binary field
-    params = %{"color" => <<9>>}
-    struct = %Post{}
+    changeset = cast(%Post{}, %{"color" => <<9>>}, ~w(color)a)
+    assert changeset.changes == %{color: <<9>>}
 
-    changeset = cast(struct, params, ~w(color)a)
-    assert changeset.changes == %{"color": <<9>>}
+    changeset = cast(%Post{}, %{"color" => <<>>}, ~w(color)a)
+    assert changeset.changes == %{}
   end
 
   test "cast/4: with force_changes" do