diff --git a/src/core/all_cases/all_cases.cc b/src/core/all_cases/all_cases.cc
index 9f0f48e..4deac7b 100644
--- a/src/core/all_cases/all_cases.cc
+++ b/src/core/all_cases/all_cases.cc
@@ -51,6 +51,7 @@ static int check_range(int head, uint32_t range) noexcept {
 
 /// Build all valid ranges of the specified head.
 void AllCases::BuildCases(int head, Ranges &release) noexcept {
+    release.clear();
     release.reserve(ALL_CASES_NUM[head]);
     auto &basic_ranges = BasicRanges::Instance().Fetch();
     for (uint32_t index = 0; index < basic_ranges.size(); ++index) {
@@ -76,30 +77,6 @@ void AllCases::Build() noexcept {
     });
 }
 
-/// Execute the build process in parallel without blocking.
-void AllCases::BuildParallelAsync(Executor &&executor, Notifier &&callback) noexcept {
-    if (available_) {
-        return; // reduce consumption of mutex
-    }
-    building_.lock();
-    if (available_) {
-        building_.unlock();
-        return; // data is already available
-    }
-    auto counter = std::make_shared<std::atomic<int>>(0);
-    auto all_done = std::make_shared<Notifier>(std::move(callback));
-    for (auto head : case_heads()) {
-        executor([this, head, counter, all_done]() {
-            BuildCases(head, GetCases()[head]);
-            if (counter->fetch_add(1) == case_heads().size() - 1) {
-                available_ = true;
-                building_.unlock(); // release building mutex
-                all_done->operator()(); // trigger callback
-            }
-        });
-    }
-}
-
 /// Execute the build process with parallel support and ensure thread safety.
 void AllCases::BuildParallel(Executor &&executor) noexcept {
     if (available_) {
@@ -126,6 +103,32 @@ void AllCases::BuildParallel(Executor &&executor) noexcept {
     available_ = true;
 }
 
+/// Execute the build process in parallel without blocking.
+void AllCases::BuildParallelAsync(Executor &&executor, Notifier &&callback) noexcept {
+    if (available_) {
+        callback();
+        return; // reduce consumption of mutex
+    }
+    building_.lock();
+    if (available_) {
+        building_.unlock();
+        callback();
+        return; // data is already available
+    }
+    auto counter = std::make_shared<std::atomic<int>>(0);
+    auto all_done = std::make_shared<Notifier>(std::move(callback));
+    for (auto head : case_heads()) {
+        executor([this, head, counter, all_done]() {
+            BuildCases(head, GetCases()[head]);
+            if (counter->fetch_add(1) == case_heads().size() - 1) { // all tasks done
+                available_ = true;
+                building_.unlock(); // release building mutex
+                all_done->operator()(); // trigger callback
+            }
+        });
+    }
+}
+
 RangesUnion& AllCases::GetCases() noexcept {
     static RangesUnion cases;
     return cases;
diff --git a/src/core/all_cases/basic_ranges.cc b/src/core/all_cases/basic_ranges.cc
index 0247e9a..1fc4b63 100644
--- a/src/core/all_cases/basic_ranges.cc
+++ b/src/core/all_cases/basic_ranges.cc
@@ -111,7 +111,7 @@ const Ranges& BasicRanges::Fetch() noexcept {
 }
 
 bool BasicRanges::IsAvailable() const noexcept {
-    return available_;
+    return available_; // no mutex required in one-way state
 }
 
 } // namespace cases
diff --git a/src/core_test/CMakeLists.txt b/src/core_test/CMakeLists.txt
index f86645a..3e70cb3 100644
--- a/src/core_test/CMakeLists.txt
+++ b/src/core_test/CMakeLists.txt
@@ -6,6 +6,8 @@ set(KLOTSKI_TEST_DEPS klotski-core gtest gtest_main md5sum)
 
 ###############################################################################################
 
+include_directories(utils)
+
 include_directories(${KLOTSKI_ROOT}/src/core/utils)
 include_directories(${KLOTSKI_ROOT}/src/core/all_cases)
 
diff --git a/src/core_test/cases/all_cases.cc b/src/core_test/cases/all_cases.cc
index d19ad04..990e111 100644
--- a/src/core_test/cases/all_cases.cc
+++ b/src/core_test/cases/all_cases.cc
@@ -1,8 +1,8 @@
 #include <string>
-#include <thread>
 #include <vector>
 
 #include "md5sum.h"
+#include "exposer.h"
 #include "all_cases.h"
 #include "gtest/gtest.h"
 #include "BS_thread_pool.hpp"
@@ -23,63 +23,47 @@ static const auto TEST_THREAD_NUM = 256;
 static const std::string ALL_CASES_MD5 = "3888e9fab8d3cbb50908b12b147cfb23";
 static const std::string BASIC_RANGES_MD5 = "6f385dc171e201089ff96bb010b47212";
 
-TEST(Cases, basic_ranges_build) {
-    std::vector<std::thread> threads;
-    threads.reserve(TEST_THREAD_NUM);
-    for (int i = 0; i < TEST_THREAD_NUM; ++i) {
-        threads.emplace_back([]() {
-            BasicRanges::Instance().Build();
-        });
-    }
-    for (auto &t : threads) {
-        t.join();
-    }
-    EXPECT_TRUE(BasicRanges::Instance().IsAvailable());
+/// Forcibly modify private variables to reset state.
+PRIVATE_ACCESS(AllCases, available_, bool)
+PRIVATE_ACCESS(BasicRanges, available_, bool)
+
+/// Reset basic ranges build state, note it is thread-unsafe.
+void basic_ranges_reset() {
+    access_BasicRanges_available_(BasicRanges::Instance()) = false;
 }
 
-TEST(Cases, basic_ranges_size) {
-    auto &basic_ranges = BasicRanges::Instance().Fetch();
-    EXPECT_EQ(basic_ranges.size(), BASIC_RANGES_NUM);
+/// Reset all cases build state, note it is thread-unsafe.
+void all_cases_reset() {
+    access_AllCases_available_(AllCases::Instance()) = false;
 }
 
-TEST(Cases, basic_ranges_data) {
+/// Verify that whether basic ranges data is correct.
+void basic_ranges_verify() {
+    auto &basic_ranges = BasicRanges::Instance().Fetch();
+    EXPECT_EQ(basic_ranges.size(), BASIC_RANGES_NUM); // verify basic ranges size
+
     std::string basic_ranges_str;
     basic_ranges_str.reserve(BASIC_RANGES_NUM * 9); // 8-bit + '\n'`
-    for (auto range : BasicRanges::Instance().Fetch()) {
+    for (auto range : basic_ranges) {
         char *tmp = nullptr;
         asprintf(&tmp, "%08X\n", range);
         basic_ranges_str += tmp;
     }
-    EXPECT_EQ(md5sum(basic_ranges_str), BASIC_RANGES_MD5);
-}
-
-TEST(Cases, all_cases_build) {
-    std::vector<std::thread> threads;
-    threads.reserve(TEST_THREAD_NUM);
-    for (int i = 0; i < TEST_THREAD_NUM; ++i) {
-        threads.emplace_back([]() {
-            AllCases::Instance().Build();
-        });
-    }
-    for (auto &t : threads) {
-        t.join();
-    }
-    EXPECT_TRUE(AllCases::Instance().IsAvailable());
+    EXPECT_EQ(md5sum(basic_ranges_str), BASIC_RANGES_MD5); // verify basic ranges checksum
 }
 
-TEST(Cases, all_cases_size) {
+/// Verify that whether all cases data is correct.
+void all_cases_verify() {
     auto &all_cases = AllCases::Instance().Fetch();
     for (int head = 0; head < 16; ++head) {
-        EXPECT_EQ(all_cases[head].size(), ALL_CASES_NUM[head]);
+        EXPECT_EQ(all_cases[head].size(), ALL_CASES_NUM[head]); // verify all cases size
     }
     auto all_cases_num = 0;
-    for (auto num : ALL_CASES_NUM) {
-        all_cases_num += num;
-    }
-    EXPECT_EQ(all_cases_num, ALL_CASES_NUM_);
-}
+    std::for_each(all_cases.begin(), all_cases.end(), [&all_cases_num](auto &ranges) {
+        all_cases_num += ranges.size();
+    });
+    EXPECT_EQ(all_cases_num, ALL_CASES_NUM_); // verify all cases global size
 
-TEST(Cases, all_cases_data) {
     std::string all_cases_str;
     all_cases_str.reserve(ALL_CASES_NUM_ * 10); // 9-bit + '\n'
     for (uint64_t head = 0; head < 16; ++head) {
@@ -89,36 +73,132 @@ TEST(Cases, all_cases_data) {
             all_cases_str += tmp;
         }
     }
-    EXPECT_EQ(md5sum(all_cases_str), ALL_CASES_MD5);
+    EXPECT_EQ(md5sum(all_cases_str), ALL_CASES_MD5); // verify all cases checksum
 }
 
-// TODO: test all_cases_parallel_build
+TEST(Cases, basic_ranges) {
+    basic_ranges_reset();
+    EXPECT_FALSE(BasicRanges::Instance().IsAvailable());
+    BasicRanges::Instance().Build();
+    EXPECT_TRUE(BasicRanges::Instance().IsAvailable());
+    BasicRanges::Instance().Build();
+    EXPECT_TRUE(BasicRanges::Instance().IsAvailable());
+    basic_ranges_verify();
+}
 
-TEST(Cases, thread_pool_demo) {
+TEST(Cases, basic_ranges_mutex) {
+    basic_ranges_reset();
+    BS::thread_pool pool(TEST_THREAD_NUM);
 
-    BasicRanges::Instance().Build();
+    for (int i = 0; i < TEST_THREAD_NUM; ++i) {
+        auto _ = pool.submit(&BasicRanges::Build, &BasicRanges::Instance());
+    }
+    EXPECT_FALSE(BasicRanges::Instance().IsAvailable());
+    pool.wait_for_tasks();
+    EXPECT_TRUE(BasicRanges::Instance().IsAvailable());
+    basic_ranges_verify();
+}
 
-    BS::thread_pool pool;
+TEST(Cases, all_cases) {
+    all_cases_reset();
+    EXPECT_FALSE(AllCases::Instance().IsAvailable());
+    AllCases::Instance().Build();
+    EXPECT_TRUE(AllCases::Instance().IsAvailable());
+    AllCases::Instance().Build();
+    EXPECT_TRUE(AllCases::Instance().IsAvailable());
+    all_cases_verify();
+}
 
-    std::cout << pool.get_thread_count() << std::endl;
+TEST(Cases, all_cases_mutex) {
+    all_cases_reset();
+    BS::thread_pool pool(TEST_THREAD_NUM);
 
-    auto start = clock();
-    auto start_ = std::chrono::high_resolution_clock::now();
+    for (int i = 0; i < TEST_THREAD_NUM; ++i) {
+        auto _ = pool.submit(&AllCases::Build, &AllCases::Instance());
+    }
+    EXPECT_FALSE(AllCases::Instance().IsAvailable());
+    pool.wait_for_tasks();
+    EXPECT_TRUE(AllCases::Instance().IsAvailable());
+    all_cases_verify();
+}
 
-    AllCases::Instance().BuildParallel([&pool](std::function<void()> &&func) {
-//        std::cout << "receive new task" << std::endl;
-        pool.push_task(func);
+TEST(Cases, all_cases_parallel) {
+    all_cases_reset();
+    BS::thread_pool executor;
+    EXPECT_FALSE(AllCases::Instance().IsAvailable());
+    AllCases::Instance().BuildParallel([&executor](auto &&func) {
+        executor.push_task(func);
     });
+    EXPECT_TRUE(AllCases::Instance().IsAvailable());
+    AllCases::Instance().BuildParallel([&executor](auto &&func) {
+        executor.push_task(func);
+    });
+    EXPECT_TRUE(AllCases::Instance().IsAvailable());
+    all_cases_verify();
+}
 
-//    std::cout << "parallel build complete" << std::endl;
+TEST(Cases, all_cases_parallel_mutex) {
+    all_cases_reset();
+    BS::thread_pool executor;
+    BS::thread_pool pool(TEST_THREAD_NUM);
 
+    for (int i = 0; i < TEST_THREAD_NUM; ++i) {
+        auto _ = pool.submit(&AllCases::BuildParallel, &AllCases::Instance(), [&executor](auto &&func) {
+            executor.push_task(func);
+        });
+    }
+    EXPECT_FALSE(AllCases::Instance().IsAvailable());
     pool.wait_for_tasks();
+    executor.wait_for_tasks();
+    EXPECT_TRUE(AllCases::Instance().IsAvailable());
+    all_cases_verify();
+}
 
-    std::cerr << ((clock() - start) * 1000 / CLOCKS_PER_SEC) << "ms" << std::endl;
-    auto end = std::chrono::high_resolution_clock::now();
-    auto elapsed = std::chrono::duration_cast<std::chrono::nanoseconds>(end - start_);
-    std::cerr << elapsed.count() / 1000 / 1000 << "ms" << std::endl;
+TEST(Cases, all_cases_async) {
+    all_cases_reset();
+    BS::thread_pool executor;
 
-//    std::cout << "pool tasks complete" << std::endl;
+    std::promise<void> promise_1;
+    auto future_1 = promise_1.get_future();
+    AllCases::Instance().BuildParallelAsync([&executor](auto &&func) {
+        executor.push_task(func);
+    }, [&promise_1]() {
+        promise_1.set_value();
+    });
+    EXPECT_FALSE(AllCases::Instance().IsAvailable());
+    future_1.wait();
+    EXPECT_TRUE(AllCases::Instance().IsAvailable());
 
+    std::promise<void> promise_2;
+    auto future_2 = promise_2.get_future();
+    AllCases::Instance().BuildParallelAsync([&executor](auto &&func) {
+        executor.push_task(func);
+    }, [&promise_2]() {
+        promise_2.set_value();
+    });
+    EXPECT_TRUE(AllCases::Instance().IsAvailable());
+    future_2.wait();
+    EXPECT_TRUE(AllCases::Instance().IsAvailable());
+    all_cases_verify();
+}
+
+TEST(Cases, all_cases_async_mutex) {
+    all_cases_reset();
+    BS::thread_pool executor;
+    std::atomic<int> callback_num(0);
+    BS::thread_pool pool(TEST_THREAD_NUM);
+
+    for (int i = 0; i < TEST_THREAD_NUM; ++i) {
+        auto _ = pool.submit(&AllCases::BuildParallelAsync, &AllCases::Instance(), [&executor](auto &&func) {
+            executor.push_task(func);
+        }, [&callback_num]() {
+            callback_num.fetch_add(1);
+        });
+    }
+    EXPECT_FALSE(AllCases::Instance().IsAvailable());
+    pool.wait_for_tasks();
+    executor.wait_for_tasks();
+    EXPECT_TRUE(AllCases::Instance().IsAvailable());
+    EXPECT_EQ(callback_num.load(), TEST_THREAD_NUM);
+    all_cases_verify();
 }
diff --git a/src/core_test/utils/exposer.h b/src/core_test/utils/exposer.h
new file mode 100644
index 0000000..e7ad736
--- /dev/null
+++ b/src/core_test/utils/exposer.h
@@ -0,0 +1,33 @@
+#pragma once
+
+/// The exposer can forcibly access private members of a class without changing
+/// any code. It uses macros to construct a function that returns a reference
+/// to the target member variable.
+
+namespace exposer {
+
+template <typename T>
+struct Exposer {
+    static T ptr;
+};
+
+template <typename T>
+T Exposer<T>::ptr;
+
+template <typename T, T Ptr>
+struct ExposerImpl {
+    static struct Factory {
+        Factory() { Exposer<T>::ptr = Ptr; }
+    } factory;
+};
+
+template <typename T, T Ptr>
+typename ExposerImpl<T, Ptr>::Factory ExposerImpl<T, Ptr>::factory;
+
+} // namespace exposer
+
+#define PRIVATE_ACCESS(Class, Member, Type)                                           \
+    template struct ::exposer::ExposerImpl<decltype(&Class::Member), &Class::Member>; \
+    Type& access_##Class##_##Member(Class &T) {                                       \
+        return T.*exposer::Exposer<Type Class::*>::ptr;                               \
+    }