feat: add pwd builtin command

src/builtins/mod.rs

@@ -5,6 +5,7 @@ use once_cell::unsync::Lazy;
 mod cd;
 mod change_prompt;
 mod exit;
+mod pwd;
 
 pub struct BuiltinConfig {
     pub prompt_style: PromptStyle,
@@ -27,6 +28,7 @@ const BUILTINS: Lazy<Vec<(&str, Box<dyn Builtin>)>> = Lazy::new(|| {
         ("cd", Box::new(cd::Cd)),
         ("change-prompt", Box::new(change_prompt::ChangePrompt)),
         ("exit", Box::new(exit::Exit)),
+        ("pwd", Box::new(pwd::Pwd)),
     ]
 });
 

src/builtins/pwd.rs

@@ -0,0 +1,15 @@
+use crate::error::ShellError;
+
+use super::{Builtin, BuiltinConfig};
+
+pub struct Pwd;
+
+impl Builtin for Pwd {
+    fn execute(&mut self, _: &mut BuiltinConfig, _: Vec<String>) -> Result<(), ShellError> {
+        match std::env::current_dir() {
+            Ok(p) => println!("{}", p.display()),
+            Err(e) => return Err(ShellError::ExecuteFailure(e.to_string())),
+        }
+        Ok(())
+    }
+}