fix: fix page guard sample test (#695)

* fix page guard sample test

* add upgraderead & upgradewrite method

Author: xx01cyx

src/storage/page/page_guard.cpp

@@ -11,6 +11,10 @@ auto BasicPageGuard::operator=(BasicPageGuard &&that) noexcept -> BasicPageGuard
 
 BasicPageGuard::~BasicPageGuard(){};  // NOLINT
 
+auto BasicPageGuard::UpgradeRead() -> ReadPageGuard { return {bpm_, page_}; }
+
+auto BasicPageGuard::UpgradeWrite() -> WritePageGuard { return {bpm_, page_}; }
+
 ReadPageGuard::ReadPageGuard(BufferPoolManager *bpm, Page *page) {}
 
 ReadPageGuard::ReadPageGuard(ReadPageGuard &&that) noexcept = default;

test/storage/page_guard_test.cpp

@@ -45,7 +45,6 @@ TEST(PageGuardTest, DISABLED_SampleTest) {
 
   {
     auto *page2 = bpm->NewPage(&page_id_temp);
-    page2->RLatch();
     auto guard2 = ReadPageGuard(bpm.get(), page2);
   }