fix: ensure compatibility std::uniform_int_distribution for binary da…

…ta generation & improve overall format

test/buffer/buffer_pool_manager_test.cpp

@@ -13,6 +13,7 @@
 #include "buffer/buffer_pool_manager.h"
 
 #include <cstdio>
+#include <limits>
 #include <random>
 #include <string>
 
@@ -29,7 +30,12 @@ TEST(BufferPoolManagerTest, DISABLED_BinaryDataTest) {
 
  std::random_device r;
  std::default_random_engine rng(r());
- std::uniform_int_distribution<char> uniform_dist(0);
+
+ constexpr int lower_bound = static_cast<int>(std::numeric_limits<char>::min());
+ constexpr int upper_bound = static_cast<int>(std::numeric_limits<char>::max());
+ // No matter if `char` is signed or unsigned by default, this constraint must be met
+ static_assert(upper_bound - lower_bound == 255);
+ std::uniform_int_distribution<int> uniform_dist(lower_bound, upper_bound);
 
  auto *disk_manager = new DiskManager(db_name);
  auto *bpm = new BufferPoolManager(buffer_pool_size, disk_manager, k);
@@ -44,7 +50,7 @@ TEST(BufferPoolManagerTest, DISABLED_BinaryDataTest) {
  char random_binary_data[BUSTUB_PAGE_SIZE];
  // Generate random binary data
  for (char &i : random_binary_data) {
- i = uniform_dist(rng);
+ i = static_cast<char>(uniform_dist(rng));
  }
 
  // Insert terminal characters both in the middle and at end
@@ -65,17 +71,20 @@ TEST(BufferPoolManagerTest, DISABLED_BinaryDataTest) {
  EXPECT_EQ(nullptr, bpm->NewPage(&page_id_temp));
  }
 
- // Scenario: After unpinning pages {0, 1, 2, 3, 4} we should be able to create 5 new pages
+ // Scenario: After unpinning pages {0, 1, 2, 3, 4}, we should be able to create 5 new pages
  for (int i = 0; i < 5; ++i) {
  EXPECT_EQ(true, bpm->UnpinPage(i, true));
  bpm->FlushPage(i);
  }
  for (int i = 0; i < 5; ++i) {
  EXPECT_NE(nullptr, bpm->NewPage(&page_id_temp));
+ // Unpin the page here to allow future fetching
  bpm->UnpinPage(page_id_temp, false);
  }
+
  // Scenario: We should be able to fetch the data we wrote a while ago.
  page0 = bpm->FetchPage(0);
+ ASSERT_NE(nullptr, page0);
  EXPECT_EQ(0, memcmp(page0->GetData(), random_binary_data, BUSTUB_PAGE_SIZE));
  EXPECT_EQ(true, bpm->UnpinPage(0, true));
 
@@ -128,10 +137,11 @@ TEST(BufferPoolManagerTest, DISABLED_SampleTest) {
 
  // Scenario: We should be able to fetch the data we wrote a while ago.
  page0 = bpm->FetchPage(0);
+ ASSERT_NE(nullptr, page0);
  EXPECT_EQ(0, strcmp(page0->GetData(), "Hello"));
 
  // Scenario: If we unpin page 0 and then make a new page, all the buffer pages should
- // now be pinned. Fetching page 0 should fail.
+ // now be pinned. Fetching page 0 again should fail.
  EXPECT_EQ(true, bpm->UnpinPage(0, true));
  EXPECT_NE(nullptr, bpm->NewPage(&page_id_temp));
  EXPECT_EQ(nullptr, bpm->FetchPage(0));