Add virtual coin loans

tests/test_official_extension_inventory.py

@@ -91,6 +91,7 @@ class LocalExtensionInventoryTests(unittest.TestCase):
                 "dice": JWEBOT_AUTHOR,
                 "coin": JWEBOT_AUTHOR,
                 "coin-transfer": JWEBOT_AUTHOR,
+                "coin-loan": JWEBOT_AUTHOR,
                 "random-number": JWEBOT_AUTHOR,
                 "draw-lot": JWEBOT_AUTHOR,
                 "daily-fortune": JWEBOT_AUTHOR,
@@ -128,6 +129,7 @@ class LocalExtensionInventoryTests(unittest.TestCase):
                     "person_memory",
                     "memory_help",
                 ),
+                "coin-loan": ("loan", "repay"),
                 "server-status": ("local_status", "server_status"),
                 "dice": ("dice", "dice_challenge"),
             },

tests/test_release_063.py

@@ -219,6 +219,33 @@ class Release063GameTests(unittest.TestCase):
         self.assertEqual(self.state()["balance"], 1000)
         self.assertEqual(self.state("Bob")["balance"], 1000)
 
+    def test_loan_repay_and_replay_once(self):
+        self.assertIn("金币 1000", self.command("/金币"))
+        first = self.command("/贷款 300", event_id="loan-1")
+        replay = self.command("/贷款 300", event_id="loan-1")
+
+        self.assertEqual(replay, first)
+        self.assertIn("贷款 300 金币已到账", first)
+        self.assertEqual(self.state()["balance"], 1300)
+        self.assertEqual(self.state()["loan"]["principal"], 300)
+        self.assertIn("未还贷款 300", self.command("/金币"))
+        self.assertIn("已有未还贷款 300", self.command("/贷款 100"))
+
+        partial = self.command("/还款 120")
+        self.assertIn("已还款 120 金币", partial)
+        self.assertEqual(self.state()["balance"], 1180)
+        self.assertEqual(self.state()["loan"]["principal"], 180)
+
+        done = self.command("/还款 全部")
+        self.assertIn("已还清贷款 180 金币", done)
+        self.assertEqual(self.state()["balance"], 1000)
+        self.assertIsNone(self.state()["loan"])
+
+    def test_loan_rejects_invalid_amounts_and_empty_repay(self):
+        self.assertIn("贷款金额必须为 1～500", self.command("/贷款 0"))
+        self.assertIn("贷款金额必须为 1～500", self.command("/loan 501"))
+        self.assertIn("当前没有未还贷款", self.command("/还款 全部"))
+
     def test_open_round_and_history_survive_restart(self):
         root = Path(self.temp.name)
         self.command("/彩票开始")