test: add cd current directory test

src/builtins/cd.rs

@@ -14,3 +14,13 @@ impl Builtin for Cd {
         set_current_dir(first).map_err(|e| ShellError::ExecuteFailure(e.to_string()))
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn cd_current() {
+        assert_eq!(Cd.execute(vec![".".to_string()]), Ok(()))
+    }
+}