feat: Add prefix config to directory module (#642)

tests/testsuite/directory.rs

@@ -95,6 +95,22 @@ fn root_directory() -> io::Result<()> {
     Ok(())
 }
 
+#[test]
+fn test_prefix() -> io::Result<()> {
+    let output = common::render_module("directory")
+        .arg("--path=/")
+        .use_config(toml::toml! {
+            [directory]
+            prefix = "sample "
+        })
+        .output()?;
+    let actual = String::from_utf8(output.stdout).unwrap();
+
+    let expected = format!("sample {} ", Color::Cyan.bold().paint("/"));
+    assert_eq!(expected, actual);
+    Ok(())
+}
+
 #[test]
 #[cfg(not(target_os = "windows"))]
 fn directory_in_root() -> io::Result<()> {