fix compile_success_empty

tooling/nargo_cli/build.rs

@@ -207,7 +207,7 @@ fn generate_compile_success_empty_tests(test_file: &mut File, test_data_dir: &Pa
         let json: serde_json::Value = serde_json::from_slice(&output.stdout).unwrap_or_else(|e| {{
             panic!("JSON was not well-formatted {:?}\n\n{:?}", e, std::str::from_utf8(&output.stdout))
         }});
-        let num_opcodes = &json["programs"][0]["functions"][0]["acir_opcodes"];
+        let num_opcodes = &json["programs"][0]["functions"][0]["opcodes"];
         assert_eq!(num_opcodes.as_u64().expect("number of opcodes should fit in a u64"), 0);
         "#;