Hold data pointer reference to AAPT2 test file

To try and solve test flakiness, hold the unique_ptr in the method scope to make sure it's cleaned up after we assert on it.

Bug: 123079798

Test: gonna merge and check for failures, since it passes locally

Change-Id: Id348d1112832cbb82f605a84ef675c25a7488b11
diff --git a/tools/aapt2/test/Fixture.cpp b/tools/aapt2/test/Fixture.cpp
index aae79fa..3fcdfb7 100644
--- a/tools/aapt2/test/Fixture.cpp
+++ b/tools/aapt2/test/Fixture.cpp
@@ -133,16 +133,18 @@
   return manifest_file;
 }
 
-void CommandTestFixture::AssertLoadXml(LoadedApk *apk, const android::StringPiece &xml_path,
+std::unique_ptr<io::IData> CommandTestFixture::OpenFileAsData(LoadedApk* apk,
+                                                              const android::StringPiece& path) {
+  return apk
+      ->GetFileCollection()
+      ->FindFile(path)
+      ->OpenAsData();
+}
+
+void CommandTestFixture::AssertLoadXml(LoadedApk* apk, const io::IData* data,
                                        android::ResXMLTree *out_tree) {
   ASSERT_THAT(apk, Ne(nullptr));
 
-  io::IFile* file = apk->GetFileCollection()->FindFile(xml_path);
-  ASSERT_THAT(file, Ne(nullptr));
-
-  std::unique_ptr<io::IData> data = file->OpenAsData();
-  ASSERT_THAT(data, Ne(nullptr));
-
   out_tree->setTo(data->data(), data->size());
   ASSERT_THAT(out_tree->getError(), Eq(android::OK));
   while (out_tree->next() != android::ResXMLTree::START_TAG) {