Ensure simulation only runs once. (#2116)

Author: fnando

cmd/soroban-cli/src/commands/contract/invoke.rs

@@ -244,16 +244,16 @@ impl NetworkRunnable for Cmd {
 
         let (function, spec, host_function_params, signers) = params;
 
-        let simulate_if_needed = || async {
-            self.simulate(&host_function_params, &default_account_entry(), &client)
-                .await
-        };
-
-        let should_send = if self.fee.build_only {
-            ShouldSend::Yes
+        // `self.fee.build_only` will be checked again below and the fn will return a TxnResult::Txn
+        // if the user passed the --build-only flag
+        let (should_send, cached_simulation) = if self.fee.build_only {
+            (ShouldSend::Yes, None)
         } else {
-            let assembled = simulate_if_needed().await?;
-            self.should_send_tx(&assembled.sim_res)?
+            let assembled = self
+                .simulate(&host_function_params, &default_account_entry(), &client)
+                .await?;
+            let should_send = self.should_send_tx(&assembled.sim_res)?;
+            (should_send, Some(assembled))
         };
 
         let account_details = if should_send == ShouldSend::Yes {
@@ -271,7 +271,9 @@ impl NetworkRunnable for Cmd {
                 );
             }
 
-            let assembled = simulate_if_needed().await?;
+            let assembled = cached_simulation.expect(
+                "cached_simulation should be available when should_send != Yes and not build_only",
+            );
             let sim_res = assembled.sim_response();
             let return_value = sim_res.results()?;
             let events = sim_res.events()?;