From cfb7dc501b5c08eb81e56662b2c11c916eeff88c Mon Sep 17 00:00:00 2001
From: unknown <michaelvictor.com272@gmail.com>
Date: Sun, 29 Mar 2026 16:42:02 +0100
Subject: [PATCH] test: add calculate_price edge case tests

- test_calculate_price_zero_reserve_a_fails
- test_calculate_price_zero_reserve_b_fails
- test_calculate_price_overflow_protection
- test_calculate_price_after_swap
---
 contract/src/market.rs | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/contract/src/market.rs b/contract/src/market.rs
index 20d454fe..bbd877f9 100644
--- a/contract/src/market.rs
+++ b/contract/src/market.rs
@@ -552,6 +552,37 @@ mod market_tests {
         assert_eq!(price, 333_333);
     }
 
+    #[test]
+    fn test_calculate_price_zero_reserve_a_fails() {
+        let result = super::calculate_price(0, 1000);
+        assert!(matches!(result, Err(InsightArenaError::InvalidInput)));
+    }
+
+    #[test]
+    fn test_calculate_price_zero_reserve_b_fails() {
+        let result = super::calculate_price(1000, 0);
+        assert!(matches!(result, Err(InsightArenaError::InvalidInput)));
+    }
+
+    #[test]
+    fn test_calculate_price_overflow_protection() {
+        // reserve_b = i128::MAX / 2 causes overflow when multiplied by 1_000_000
+        let result = super::calculate_price(1, i128::MAX / 2);
+        assert!(matches!(result, Err(InsightArenaError::Overflow)));
+    }
+
+    #[test]
+    fn test_calculate_price_after_swap() {
+        // Initial: 1000/1000 -> price = 1_000_000
+        let initial = super::calculate_price(1000, 1000).unwrap();
+        assert_eq!(initial, 1_000_000);
+
+        // After swap: reserve_a = 1100, reserve_b = 909 -> price changes
+        let after = super::calculate_price(1100, 909).unwrap();
+        assert_eq!(after, 826_363);
+        assert!(after < initial);
+    }
+
     /// Register a mock XLM token (Stellar Asset Contract) and return its address.
     fn register_token(env: &Env) -> Address {
         let token_admin = Address::generate(env);