diff --git a/.github/workflows/python-build.yml b/.github/workflows/python-build.yml
index 0089a622..91581e93 100644
--- a/.github/workflows/python-build.yml
+++ b/.github/workflows/python-build.yml
@@ -24,7 +24,7 @@ jobs:
 
     - name: Test - Code format
       run: |
-        black --check --diff --color pdf2zh/*.py
+        black --check --diff --color pdf2zh/*.py test/*.py
         flake8 --ignore E203,E261,E501,W503,E741
     
     - name: Test - Unit Test
diff --git a/test/test_cache.py b/test/test_cache.py
new file mode 100644
index 00000000..d22db984
--- /dev/null
+++ b/test/test_cache.py
@@ -0,0 +1,108 @@
+import unittest
+import os
+import tempfile
+import shutil
+import time
+from pdf2zh import cache
+
+
+class TestCache(unittest.TestCase):
+    def setUp(self):
+        # Create a temporary directory for testing
+        self.test_cache_dir = os.path.join(tempfile.gettempdir(), "test_cache")
+        self.original_cache_dir = cache.cache_dir
+        cache.cache_dir = self.test_cache_dir
+        os.makedirs(self.test_cache_dir, exist_ok=True)
+
+    def tearDown(self):
+        # Clean up the test directory
+        shutil.rmtree(self.test_cache_dir)
+        cache.cache_dir = self.original_cache_dir
+
+    def test_deterministic_hash(self):
+        # Test hash generation for different inputs
+        test_input = "Hello World"
+        hash1 = cache.deterministic_hash(test_input)
+        hash2 = cache.deterministic_hash(test_input)
+        self.assertEqual(hash1, hash2)
+        self.assertEqual(len(hash1), 20)
+
+        # Test different inputs produce different hashes
+        hash3 = cache.deterministic_hash("Different input")
+        self.assertNotEqual(hash1, hash3)
+
+    def test_get_dirs(self):
+        # Create test directories
+        test_dirs = ["dir1", "dir2", "dir3"]
+        for dir_name in test_dirs:
+            os.makedirs(os.path.join(self.test_cache_dir, dir_name))
+
+        # Create a file (should be ignored)
+        with open(os.path.join(self.test_cache_dir, "test.txt"), "w") as f:
+            f.write("test")
+
+        dirs = cache.get_dirs()
+        self.assertEqual(len(dirs), 3)
+        for dir_path in dirs:
+            self.assertTrue(os.path.isdir(dir_path))
+
+    def test_get_time(self):
+        # Create test directory with time file
+        test_dir = os.path.join(self.test_cache_dir, "test_dir")
+        os.makedirs(test_dir)
+        test_time = 1234567890.0
+
+        with open(os.path.join(test_dir, cache.time_filename), "w") as f:
+            f.write(str(test_time))
+
+        # Test reading time
+        result = cache.get_time(test_dir)
+        self.assertEqual(result, test_time)
+
+        # Test non-existent directory
+        non_existent_dir = os.path.join(self.test_cache_dir, "non_existent")
+        result = cache.get_time(non_existent_dir)
+        self.assertEqual(result, float("inf"))
+
+    def test_write_time(self):
+        test_dir = os.path.join(self.test_cache_dir, "test_dir")
+        os.makedirs(test_dir)
+
+        cache.write_time(test_dir)
+
+        self.assertTrue(os.path.exists(os.path.join(test_dir, cache.time_filename)))
+        with open(os.path.join(test_dir, cache.time_filename)) as f:
+            time_value = float(f.read())
+        self.assertIsInstance(time_value, float)
+
+    def test_remove_extra(self):
+        # Create more than max_cache directories
+        for i in range(cache.max_cache + 2):
+            dir_path = os.path.join(self.test_cache_dir, f"dir{i}")
+            os.makedirs(dir_path)
+            time.sleep(0.1)  # Ensure different timestamps
+            cache.write_time(dir_path)
+
+        cache.remove_extra()
+
+        remaining_dirs = cache.get_dirs()
+        self.assertLessEqual(len(remaining_dirs), cache.max_cache)
+
+    def test_cache_operations(self):
+        test_hash = "test123hash"
+        test_para_hash = "para456hash"
+        test_content = "Test paragraph content"
+
+        # Test cache creation
+        self.assertFalse(cache.is_cached(test_hash))
+        cache.create_cache(test_hash)
+        self.assertTrue(cache.is_cached(test_hash))
+
+        # Test paragraph operations
+        self.assertIsNone(cache.load_paragraph(test_hash, test_para_hash))
+        cache.write_paragraph(test_hash, test_para_hash, test_content)
+        self.assertEqual(cache.load_paragraph(test_hash, test_para_hash), test_content)
+
+
+if __name__ == "__main__":
+    unittest.main()