Apply noexec option

yash-semantics/src/command/pipeline.rs

@@ -22,6 +22,8 @@ use std::ops::ControlFlow::{Break, Continue};
 use std::rc::Rc;
 use yash_env::io::Fd;
 use yash_env::job::Pid;
+use yash_env::option::Option::Exec;
+use yash_env::option::State::Off;
 use yash_env::semantics::Divert;
 use yash_env::semantics::ExitStatus;
 use yash_env::semantics::Result;
@@ -57,13 +59,22 @@ use yash_syntax::syntax;
 /// shells. This implementation does not invert the exit status when the return
 /// value is `Err(Divert::...)`, which is different from yash 2.
 ///
+/// # `noexec` option
+///
+/// If the `Exec` option is `Off` in `env.options`, the entire execution of the
+/// pipeline is skipped.
+///
 /// # Stack
 ///
 /// if `self.negation` is true, [`Frame::Condition`] is pushed to the
 /// environment's stack while the pipeline is executed.
 #[async_trait(?Send)]
 impl Command for syntax::Pipeline {
     async fn execute(&self, env: &mut Env) -> Result {
+        if env.options.get(Exec) == Off {
+            return Continue(());
+        }
+
         if !self.negation {
             return execute_commands_in_pipeline(env, &self.commands).await;
         }
@@ -252,6 +263,7 @@ mod tests {
     use std::rc::Rc;
     use yash_env::builtin::Builtin;
     use yash_env::builtin::Type::Special;
+    use yash_env::option::State::Off;
     use yash_env::semantics::Field;
     use yash_env::system::r#virtual::FileBody;
     use yash_env::system::r#virtual::ProcessState;
@@ -410,6 +422,17 @@ mod tests {
         assert_eq!(env.exit_status, ExitStatus(15));
     }
 
+    #[test]
+    fn noexec_option() {
+        let mut env = Env::new_virtual();
+        env.builtins.insert("return", return_builtin());
+        env.options.set(Exec, Off);
+        let pipeline: syntax::Pipeline = "return -n 93".parse().unwrap();
+        let result = pipeline.execute(&mut env).now_or_never().unwrap();
+        assert_eq!(result, Continue(()));
+        assert_eq!(env.exit_status, ExitStatus::SUCCESS);
+    }
+
     #[test]
     fn stack_without_inversion() {
         fn stub_builtin(