feat(blockifier): safe addition of fee amounts in business logic (#1255)

<!-- Reviewable:start -->
This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/starkware-libs/sequencer/1255)
<!-- Reviewable:end -->

crates/blockifier/src/fee/fee_utils.rs

@@ -109,26 +109,7 @@ pub fn verify_can_pay_committed_bounds(
 ) -> TransactionFeeResult<()> {
     let tx_info = &tx_context.tx_info;
     let committed_fee = match tx_info {
-        TransactionInfo::Current(context) => {
-            match &context.resource_bounds {
-                L1Gas(l1_gas) =>
-                // Sender will not be charged by `max_price_per_unit`, but this check should not
-                // depend on the current gas price.
-                {
-                    l1_gas.max_amount.saturating_mul(l1_gas.max_price_per_unit)
-                }
-                // TODO!(Aner): add tests
-                AllResources(AllResourceBounds { l1_gas, l2_gas, l1_data_gas }) => {
-                    // Committed fee is sum of products (resource_max_amount * resource_max_price)
-                    // of the different resources.
-                    // The Sender will not be charged by`max_price_per_unit`, but this check should
-                    // not depend on the current gas price
-                    l1_gas.max_amount.saturating_mul(l1_gas.max_price_per_unit)
-                        + l1_data_gas.max_amount.saturating_mul(l1_data_gas.max_price_per_unit)
-                        + l2_gas.max_amount.saturating_mul(l2_gas.max_price_per_unit)
-                }
-            }
-        }
+        TransactionInfo::Current(context) => context.resource_bounds.max_possible_fee(),
         TransactionInfo::Deprecated(context) => context.max_fee,
     };
     let (balance_low, balance_high, can_pay) =

crates/starknet_api/src/transaction.rs

@@ -723,6 +723,7 @@ pub struct RevertedTransactionExecutionStatus {
 }
 
 /// A fee.
+#[cfg_attr(any(test, feature = "testing"), derive(derive_more::Add, derive_more::Deref))]
 #[derive(
     Debug,
     Copy,
@@ -736,8 +737,6 @@ pub struct RevertedTransactionExecutionStatus {
     Serialize,
     PartialOrd,
     Ord,
-    derive_more::Add,
-    derive_more::Deref,
 )]
 #[serde(from = "PrefixedBytesAsHex<16_usize>", into = "PrefixedBytesAsHex<16_usize>")]
 pub struct Fee(pub u128);
@@ -747,6 +746,10 @@ impl Fee {
         self.0.checked_add(rhs.0).map(Fee)
     }
 
+    pub fn saturating_add(self, rhs: Self) -> Self {
+        Self(self.0.saturating_add(rhs.0))
+    }
+
     pub fn checked_div_ceil(self, rhs: NonzeroGasPrice) -> Option<GasAmount> {
         match self.checked_div(rhs) {
             Some(value) => Some(if value.nonzero_saturating_mul(rhs) < self {
@@ -1119,11 +1122,13 @@ impl ValidResourceBounds {
                 l1_gas,
                 l2_gas,
                 l1_data_gas,
-            }) => {
-                l1_gas.max_amount.saturating_mul(l1_gas.max_price_per_unit)
-                    + l2_gas.max_amount.saturating_mul(l2_gas.max_price_per_unit)
-                    + l1_data_gas.max_amount.saturating_mul(l1_data_gas.max_price_per_unit)
-            }
+            }) => l1_gas
+                .max_amount
+                .saturating_mul(l1_gas.max_price_per_unit)
+                .saturating_add(l2_gas.max_amount.saturating_mul(l2_gas.max_price_per_unit))
+                .saturating_add(
+                    l1_data_gas.max_amount.saturating_mul(l1_data_gas.max_price_per_unit),
+                ),
         }
     }