--- a/rust/rhg/src/commands/root.rs	Tue Jul 21 10:39:30 2020 +0200
+++ b/rust/rhg/src/commands/root.rs	Mon Jul 20 18:14:52 2020 +0200
@@ -1,9 +1,8 @@
 use crate::commands::Command;
 use crate::error::{CommandError, CommandErrorKind};
 use crate::ui::Ui;
-use hg::operations::{FindRoot, FindRootError, FindRootErrorKind};
+use hg::operations::{FindRoot, FindRootErrorKind};
 use hg::utils::files::get_bytes_from_path;
-use std::path::PathBuf;
 
 pub const HELP_TEXT: &str = "
 Print the root directory of the current repository.
@@ -11,19 +10,28 @@
 Returns 0 on success.
 ";
 
-pub struct RootCommand {
-    ui: Ui,
+pub struct RootCommand<'a> {
+    ui: &'a Ui,
+}
+
+impl<'a> RootCommand<'a> {
+    pub fn new(ui: &'a Ui) -> Self {
+        RootCommand { ui }
+    }
 }
 
-impl RootCommand {
-    pub fn new() -> Self {
-        RootCommand { ui: Ui::new() }
-    }
+impl<'a> Command<'a> for RootCommand<'a> {
+    fn run(&self) -> Result<(), CommandError> {
+        let path_buf =
+            FindRoot::new().run().map_err(|err| match err.kind {
+                FindRootErrorKind::RootNotFound(path) => {
+                    CommandErrorKind::RootNotFound(path)
+                }
+                FindRootErrorKind::GetCurrentDirError(e) => {
+                    CommandErrorKind::CurrentDirNotFound(e)
+                }
+            })?;
 
-    fn display_found_path(
-        &self,
-        path_buf: PathBuf,
-    ) -> Result<(), CommandError> {
         let bytes = get_bytes_from_path(path_buf);
 
         // TODO use formating macro
@@ -31,46 +39,4 @@
 
         Ok(())
     }
-
-    fn display_error(&self, error: FindRootError) -> Result<(), CommandError> {
-        match error.kind {
-            FindRootErrorKind::RootNotFound(path) => {
-                let bytes = get_bytes_from_path(path);
-
-                // TODO use formating macro
-                self.ui.write_stderr(
-                    &[
-                        b"abort: no repository found in '",
-                        bytes.as_slice(),
-                        b"' (.hg not found)!\n",
-                    ]
-                    .concat(),
-                )?;
-
-                Err(CommandErrorKind::RootNotFound.into())
-            }
-            FindRootErrorKind::GetCurrentDirError(e) => {
-                // TODO use formating macro
-                self.ui.write_stderr(
-                    &[
-                        b"abort: error getting current working directory: ",
-                        e.to_string().as_bytes(),
-                        b"\n",
-                    ]
-                    .concat(),
-                )?;
-
-                Err(CommandErrorKind::CurrentDirNotFound.into())
-            }
-        }
-    }
 }
-
-impl Command for RootCommand {
-    fn run(&self) -> Result<(), CommandError> {
-        match FindRoot::new().run() {
-            Ok(path_buf) => self.display_found_path(path_buf),
-            Err(e) => self.display_error(e),
-        }
-    }
-}