Add support for custom subcommands (#2814)

* Add support for custom subcommands

* clippy

crates/nu-parser/src/parse.rs

@@ -2130,7 +2130,7 @@ fn parse_definition(call: &LiteCommand, scope: &dyn ParserScope) -> Option<Parse
             return Some(ParseError::mismatch("definition", call.parts[0].clone()));
         }
 
-        let name = call.parts[1].item.clone();
+        let name = trim_quotes(&call.parts[1].item);
         let (signature, err) = parse_signature(&name, &call.parts[2], scope);
         if err.is_some() {
             return err;
@@ -2151,11 +2151,10 @@ fn parse_definition(call: &LiteCommand, scope: &dyn ParserScope) -> Option<Parse
                     return err;
                 };
 
-                let name = &call.parts[1].item;
                 let (mut block, err) = classify_block(&lite_block, scope);
 
                 block.params = signature;
-                block.params.name = name.clone();
+                block.params.name = name;
 
                 scope.add_definition(block);
 
@@ -2181,7 +2180,7 @@ fn parse_definition_prototype(call: &LiteCommand, scope: &dyn ParserScope) -> Op
         return Some(ParseError::mismatch("definition", call.parts[0].clone()));
     }
 
-    let name = call.parts[1].item.clone();
+    let name = trim_quotes(&call.parts[1].item);
     let (signature, error) = parse_signature(&name, &call.parts[2], scope);
     if err.is_none() {
         err = error;

tests/shell/pipeline/commands/internal.rs

@@ -368,6 +368,18 @@ fn run_custom_command_with_flag_missing() {
     assert_eq!(actual.out, "empty");
 }
 
+#[test]
+fn run_custom_subcommand() {
+    let actual = nu!(
+        cwd: ".",
+        r#"
+        def "str double" [x] { echo $x $x | str collect }; str double bob
+        "#
+    );
+
+    assert_eq!(actual.out, "bobbob");
+}
+
 #[test]
 fn set_variable() {
     let actual = nu!(