chore(payments): add fees to trade event (#21)

Author: MohammadNassar1

src/events.cairo

@@ -50,6 +50,8 @@ pub struct TradeExecuted {
     pub buy_token: ContractAddress,
     pub order_a_sell_amount: u128,
     pub order_a_buy_amount: u128,
+    pub fee_a: u128,
+    pub fee_b: u128,
 }
 
 #[derive(Debug, Drop, PartialEq, starknet::Event)]

src/payments.cairo

@@ -211,43 +211,43 @@ pub mod payments {
 
             // Take fees.
             let fee_recipient = self.fee_recipient.read();
-            let fee_1 = self._calculate_fee(order_a_actual_sell_amount);
+            let fee_a = self._calculate_fee(order_a_actual_sell_amount);
             // For `order_b`, the actual sold amount is `order_a_actual_buy_amount`.
-            let fee_2 = self._calculate_fee(order_a_actual_buy_amount);
+            let fee_b = self._calculate_fee(order_a_actual_buy_amount);
             assert_with_byte_array(
-                sell_token.transfer_from(order_a.user, fee_recipient, fee_1.into()),
+                sell_token.transfer_from(order_a.user, fee_recipient, fee_a.into()),
                 transfer_failed_error(
-                    token: order_a.sell_token, sender: order_a.user, amount: fee_1,
+                    token: order_a.sell_token, sender: order_a.user, amount: fee_a,
                 ),
             );
             assert_with_byte_array(
-                buy_token.transfer_from(order_b.user, fee_recipient, fee_2.into()),
+                buy_token.transfer_from(order_b.user, fee_recipient, fee_b.into()),
                 transfer_failed_error(
-                    token: order_a.buy_token, sender: order_b.user, amount: fee_2,
+                    token: order_a.buy_token, sender: order_b.user, amount: fee_b,
                 ),
             );
 
             // Transfer the actual amounts.
             assert_with_byte_array(
                 sell_token
                     .transfer_from(
-                        order_a.user, order_b.user, (order_a_actual_sell_amount - fee_1).into(),
+                        order_a.user, order_b.user, (order_a_actual_sell_amount - fee_a).into(),
                     ),
                 transfer_failed_error(
                     token: order_a.sell_token,
                     sender: order_a.user,
-                    amount: order_a_actual_sell_amount - fee_1,
+                    amount: order_a_actual_sell_amount - fee_a,
                 ),
             );
             assert_with_byte_array(
                 buy_token
                     .transfer_from(
-                        order_b.user, order_a.user, (order_a_actual_buy_amount - fee_2).into(),
+                        order_b.user, order_a.user, (order_a_actual_buy_amount - fee_b).into(),
                     ),
                 transfer_failed_error(
                     token: order_a.buy_token,
                     sender: order_b.user,
-                    amount: order_a_actual_buy_amount - fee_2,
+                    amount: order_a_actual_buy_amount - fee_b,
                 ),
             );
 
@@ -261,6 +261,8 @@ pub mod payments {
                         buy_token: order_a.buy_token,
                         order_a_sell_amount: order_a_actual_sell_amount,
                         order_a_buy_amount: order_a_actual_buy_amount,
+                        fee_a,
+                        fee_b,
                     },
                 );
         }

src/tests/test_payments.cairo

@@ -843,6 +843,8 @@ fn test_successful_trade() {
         buy_token: token_b,
         order_a_sell_amount: 7560,
         order_a_buy_amount: 850,
+        fee_a: 76,
+        fee_b: 9,
     };
     assert_expected_event_emitted(
         spied_event: events[4],