image_test should include at least one DexFile

Change-Id: Ica6d6fa39f10f5efda549fbb7ef08bc00404e4de
diff --git a/src/image_test.cc b/src/image_test.cc
index 57afe68..f5f96d8 100644
--- a/src/image_test.cc
+++ b/src/image_test.cc
@@ -19,6 +19,7 @@
 TEST_F(ImageTest, WriteRead) {
   ScratchFile tmp_oat;
   std::vector<const DexFile*> dex_files;
+  dex_files.push_back(GetLibCoreDex());
   bool success_oat = OatWriter::Create(tmp_oat.GetFile(), NULL, dex_files, *compiler_.get());
   ASSERT_TRUE(success_oat);