diff --git a/test_character_builder.py b/test_character_builder.py
new file mode 100644
index 0000000..135f49f
--- /dev/null
+++ b/test_character_builder.py
@@ -0,0 +1,121 @@
+import unittest
+from unittest.mock import patch
+import json
+import pathlib
+
+from base_mob import BaseMob
+from character_builder import CharacterBuilder
+
+ARTHUR_JSON = """{
+    "name": "Arthur",
+    "max_pv": 100,
+    "current_pv": 100,
+    "strength": 20,
+    "protection": 10,
+    "speed": 5,
+    "mob_type": 0
+}"""
+
+ARTHUR_FILE = pathlib.Path('Arthur.json')
+
+
+class TestCharacterBuilder(unittest.TestCase):
+
+    @classmethod
+    def tearDownClass(cls):
+        ARTHUR_FILE.unlink(missing_ok=True)
+
+    @patch("builtins.input")
+    def test_build_character(self, mock_input):
+        # Arrange
+        mock_input.side_effect = [
+            "Arthur",  # name
+            "100",  # max_pv
+            "20",  # strength
+            "10",  # protection
+            "5"  # speed
+        ]
+
+        # Act
+        character = CharacterBuilder.build_character()
+
+        # Assert
+        self.assertIsInstance(character, BaseMob)
+        self.assertEqual(character.name, "Arthur")
+        self.assertEqual(character.max_pv, 100)
+        self.assertEqual(character.strength, 20)
+        self.assertEqual(character.protection, 10)
+        self.assertEqual(character.speed, 5)
+        self.assertEqual(character.mob_type, 0)
+
+    def test_save_character(self):
+        # Arrange
+        character = BaseMob(
+            name="Arthur",
+            max_pv=100,
+            strength=20,
+            protection=10,
+            speed=5,
+            mob_type=0,
+        )
+
+        # Act
+        CharacterBuilder.save_character(character)
+
+        # Assert
+        self.assertTrue(ARTHUR_FILE.exists())
+        self.assertEqual(ARTHUR_JSON, ARTHUR_FILE.read_text(encoding='utf-8'))
+
+    def test_load_character_file_not_found(self):
+        # Act
+        result = CharacterBuilder.load_character("Lancelot")
+
+        # Assert
+        self.assertIsNone(result)
+
+    def test_load_character_success(self):
+        # Arrange
+        ARTHUR_FILE.write_text(ARTHUR_JSON, encoding='utf-8')
+
+        # Act
+        character = CharacterBuilder.load_character("Arthur")
+
+        # Assert
+        self.assertIsNotNone(character)
+        self.assertEqual(character.name, "Arthur")
+        self.assertEqual(character.max_pv, 100)
+        self.assertEqual(character.strength, 20)
+        self.assertEqual(character.protection, 10)
+        self.assertEqual(character.speed, 5)
+        self.assertEqual(character.mob_type, 0)
+
+    def test_load_character_missing_keys(self):
+        arthur_dict: dict = json.loads(ARTHUR_JSON)
+
+        for key in arthur_dict:
+            with self.subTest(f'test without key "{key}"'):
+                # Arrange
+                invalid_dict = arthur_dict.copy()
+                invalid_dict.pop(key)
+                ARTHUR_FILE.write_text(json.dumps(
+                    invalid_dict), encoding='utf-8')
+
+                # Act
+                result = CharacterBuilder.load_character("Arthur")
+
+                # Assert
+                self.assertIsNone(result)
+
+    def test_load_character_invalid_json(self):
+        # Arrange
+        ARTHUR_FILE.write_text(ARTHUR_JSON[1:], encoding='utf-8')
+
+        # Act
+        result = CharacterBuilder.load_character("Arthur")
+
+        # Assert
+        self.assertIsNone(result)
+
+
+if __name__ == "__main__":
+    unittest.main()