extend mock runtime to allow executing constructors and cross contract calls

Signed-off-by: xermicus <cyrill@parity.io>

crates/integration/src/cases.rs

@@ -1,6 +1,8 @@
 use alloy_primitives::{I256, U256};
 use alloy_sol_types::{sol, SolCall};
 
+use crate::mock_runtime::{CallOutput, State};
+
 #[derive(Clone)]
 pub struct Contract {
     pub name: &'static str,
@@ -103,6 +105,24 @@ sol!(
 );
 
 impl Contract {
+    /// Execute the contract.
+    ///
+    /// Useful helper if the contract state can be ignored,
+    /// as it spares the deploy transaciton.
+    ///
+    /// - Inserts an account with given `code` into a new state.
+    /// - Callee and caller account will be `Transaction::default_address()`.
+    /// - Sets the calldata.
+    /// - Doesn't execute the constructor or deploy code.
+    /// - Calls the "call" export on a default backend config.
+    pub fn execute(&self) -> (State, CallOutput) {
+        State::default()
+            .transaction()
+            .with_default_account(&self.pvm_runtime)
+            .calldata(self.calldata.clone())
+            .call()
+    }
+
     pub fn baseline() -> Self {
         let code = include_str!("../contracts/Baseline.sol");
         let name = "Baseline";