test: add gas_left function test

examples/properties.rs

@@ -60,6 +60,11 @@ pub fn timestamp() -> u64 {
     properties::timestamp()
 }
 
+#[zink::external]
+pub fn gasleft() -> Bytes32 {
+    properties::gasleft()
+}
+
 #[cfg(not(target_arch = "wasm32"))]
 fn main() {}
 
@@ -193,4 +198,27 @@ mod tests {
         assert_eq!(info.ret, 26u64.to_bytes32(), "{info:?}");
         Ok(())
     }
+
+    #[test]
+    fn test_gas_left() -> anyhow::Result<()> {
+        let contract = Contract::search("properties")?.compile()?;
+
+        let mut evm1 = EVM::default().tx_gas_limit(50000).commit(true);
+        let info1 = evm1.deploy(&contract.bytecode()?)?;
+        let info1 = evm1
+            .calldata(&contract.encode(["gasleft()".as_bytes()])?)
+            .call(info1.address)?;
+        let gasleft1 = u64::from_be_bytes(info1.ret[24..].try_into().unwrap());
+        let gas1 = 50000 - gasleft1;
+
+        let mut evm2 = EVM::default().tx_gas_limit(70000).commit(true);
+        let info2 = evm2.deploy(&contract.bytecode()?)?;
+        let info2 = evm2
+            .calldata(&contract.encode(["gasleft()".as_bytes()])?)
+            .call(info2.address)?;
+        let gasleft2 = u64::from_be_bytes(info2.ret[24..].try_into().unwrap());
+        let gas2 = 70000 - gasleft2;
+        assert_eq!(gas1, gas2);
+        Ok(())
+    }
 }

zink/src/ffi/evm.rs

@@ -183,7 +183,7 @@ extern "C" {
     pub fn gaslimit() -> Bytes32;
 
     /// Get the amount of available gas.
-    pub fn gas() -> u64;
+    pub fn gas() -> Bytes32;
 
     /// Get the block’s timestamp.
     pub fn timestamp() -> u64;

zink/src/primitives/properties.rs

@@ -47,7 +47,7 @@ pub fn gaslimit() -> Bytes32 {
 }
 
 /// Get the amount of available gas.
-pub fn gas() -> u64 {
+pub fn gasleft() -> Bytes32 {
     unsafe { ffi::evm::gas() }
 }
 

zink/zint/src/evm.rs

@@ -27,6 +27,8 @@ pub struct EVM<'e> {
     pub caller: [u8; 20],
     /// Blob hashes
     pub blob_hashes: Option<Vec<B256>>,
+    /// The gas limit of the transaction
+    pub tx_gas_limit: u64,
     /// If commit changes
     commit: bool,
 }
@@ -41,6 +43,7 @@ impl<'e> Default for EVM<'e> {
             inner: evm,
             caller: [0; 20],
             blob_hashes: None,
+            tx_gas_limit: GAS_LIMIT,
             commit: false,
         }
     }
@@ -148,10 +151,16 @@ impl EVM<'_> {
         self
     }
 
+    /// Set tx’s gaslimit
+    pub fn tx_gas_limit(mut self, gaslimit: u64) -> Self {
+        self.tx_gas_limit = gaslimit;
+        self
+    }
+
     /// Send transaction to the provided address.
     pub fn call(&mut self, to: [u8; 20]) -> Result<Info> {
         let to = TransactTo::Call(to.into());
-        self.inner.tx_mut().gas_limit = GAS_LIMIT;
+        self.inner.tx_mut().gas_limit = self.tx_gas_limit;
         self.inner.tx_mut().transact_to = to;
         self.inner.tx_mut().caller = self.caller.into();
         if let Some(hashes) = &self.blob_hashes {