test/test_translate_song: move MakeTag() to header

test/MakeTag.hxx

+/*
+ * Copyright 2003-2019 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "tag/Builder.hxx"
+#include "tag/Tag.hxx"
+#include "util/Compiler.h"
+
+static void
+BuildTag(gcc_unused TagBuilder &tag)
+{
+}
+
+template<typename... Args>
+static void
+BuildTag(TagBuilder &tag, TagType type, const char *value, Args&&... args)
+{
+	tag.AddItem(type, value);
+	BuildTag(tag, std::forward<Args>(args)...);
+}
+
+template<typename... Args>
+static Tag
+MakeTag(Args&&... args)
+{
+	TagBuilder tag;
+	BuildTag(tag, std::forward<Args>(args)...);
+	return tag.Commit();
+}

test/test_translate_song.cxx

@@ -2,6 +2,7 @@
  * Unit tests for playlist_check_translate_song().
  */
 
+#include "MakeTag.hxx"
 #include "playlist/PlaylistSong.hxx"
 #include "song/DetachedSong.hxx"
 #include "SongLoader.hxx"
@@ -38,28 +39,6 @@ uri_supported_scheme(const char *uri) noexcept
 static constexpr auto music_directory = PATH_LITERAL("/music");
 static Storage *storage;
 
-static void
-BuildTag(gcc_unused TagBuilder &tag)
-{
-}
-
-template<typename... Args>
-static void
-BuildTag(TagBuilder &tag, TagType type, const char *value, Args&&... args)
-{
-	tag.AddItem(type, value);
-	BuildTag(tag, std::forward<Args>(args)...);
-}
-
-template<typename... Args>
-static Tag
-MakeTag(Args&&... args)
-{
-	TagBuilder tag;
-	BuildTag(tag, std::forward<Args>(args)...);
-	return tag.Commit();
-}
-
 static Tag
 MakeTag1a()
 {