Repository: google/argh (rust)

Issue:
Clippy warnings
Derived code is triggering Clippy warnings, more specifically:

* clippy::indexing_slicing,
* clippy::panic_in_result_fn,
* clippy::str_to_string,
* clippy::unreachable,
* clippy::unwrap_in_result

Please consider using `#[automatically_derived]`/`#[allow(clippy::SOME_LINT]` or audit the codebase.

Pull request:
Fix clippy lints; return errors rather than panic
This cleans up clippy lints, both in the library itself, and in the
generated code. As part of this change, it changes a few locations where
we would have panicked on values passed in by the user to instead return
an error.

However, I left one place that unwraps in the generated code. After we have
parsed all the arguments, we check that all of the required arguments. If
not, we return an error. It's unfortunately a little difficult to prove
to rust that we've handled all the arguments. I left the unwrap()s in place
in case there's a logic error we have in handling this, and annotated the
code with `#[allow(clippy::unwrap_in_result)]` to allow for this case.

Closes #114

Patch:
diff --git a/.github/workflows/rust.yml b/.github/workflows/rust.yml
index d307088..02b22a7 100644
--- a/.github/workflows/rust.yml
+++ b/.github/workflows/rust.yml
@@ -15,3 +15,5 @@ jobs:
       run: cargo build --verbose
     - name: Run tests
       run: cargo test --verbose
+    - name: Run clippy
+      run: cargo clippy -- -D warnings
diff --git a/argh/src/lib.rs b/argh/src/lib.rs
index 984d927..1bd6ba9 100644
--- a/argh/src/lib.rs
+++ b/argh/src/lib.rs
@@ -31,9 +31,7 @@
 //!     pilot_nickname: Option<String>,
 //! }
 //!
-//! fn main() {
-//!     let up: GoUp = argh::from_env();
-//! }
+//! let up: GoUp = argh::from_env();
 //! ```
 //!
 //! `./some_bin --help` will then output the following:
@@ -481,8 +479,8 @@ impl From<String> for EarlyExit {
 }
 
 /// Extract the base cmd from a path
-fn cmd<'a>(default: &'a String, path: &'a String) -> &'a str {
-    std::path::Path::new(path).file_name().map(|s| s.to_str()).flatten().unwrap_or(default.as_str())
+fn cmd<'a>(default: &'a str, path: &'a str) -> &'a str {
+    std::path::Path::new(path).file_name().map(|s| s.to_str()).flatten().unwrap_or(default)
 }
 
 /// Create a `FromArgs` type from the current process's `env::args`.
@@ -690,7 +688,7 @@ pub fn parse_struct_args(
             continue;
         }
 
-        if next_arg.starts_with("-") && !options_ended {
+        if next_arg.starts_with('-') && !options_ended {
             if next_arg == "--" {
                 options_ended = true;
                 continue;
@@ -877,7 +875,7 @@ impl<'a> ParseStructSubCommand<'a> {
             }
         }
 
-        return Ok(false);
+        Ok(false)
     }
 }
 
@@ -951,7 +949,7 @@ impl MissingRequirements {
 
         if !self.options.is_empty() {
             if !self.positional_args.is_empty() {
-                output.push_str("\n");
+                output.push('\n');
             }
             output.push_str("Required options not provided:");
             for option in &self.options {
@@ -962,7 +960,7 @@ impl MissingRequirements {
 
         if let Some(missing_subcommands) = self.subcommands {
             if !self.options.is_empty() {
-                output.push_str("\n");
+                output.push('\n');
             }
             output.push_str("One of the following subcommands must be present:");
             output.push_str(NEWLINE_INDENT);
diff --git a/argh_derive/src/help.rs b/argh_derive/src/help.rs
index 5bf02b1..c295825 100644
--- a/argh_derive/src/help.rs
+++ b/argh_derive/src/help.rs
@@ -96,7 +96,7 @@ pub(crate) fn help(
 
     lits_section(&mut format_lit, "Notes:", &ty_attrs.notes);
 
-    if ty_attrs.error_codes.len() != 0 {
+    if !ty_attrs.error_codes.is_empty() {
         format_lit.push_str(SECTION_SEPARATOR);
         format_lit.push_str("Error codes:");
         for (code, text) in &ty_attrs.error_codes {
@@ -106,7 +106,7 @@ pub(crate) fn help(
         }
     }
 
-    format_lit.push_str("\n");
+    format_lit.push('\n');
 
     quote! { {
         #subcommand_calculation
@@ -116,7 +116,7 @@ pub(crate) fn help(
 
 /// A section composed of exactly just the literals provided to the program.
 fn lits_section(out: &mut String, heading: &str, lits: &[syn::LitStr]) {
-    if lits.len() != 0 {
+    if !lits.is_empty() {
         out.push_str(SECTION_SEPARATOR);
         out.push_str(heading);
         for lit in lits {
diff --git a/argh_derive/src/lib.rs b/argh_derive/src/lib.rs
index a123d4e..ab72a40 100644
--- a/argh_derive/src/lib.rs
+++ b/argh_derive/src/lib.rs
@@ -35,7 +35,7 @@ pub fn argh_derive(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
 /// as well as all errors that occurred.
 fn impl_from_args(input: &syn::DeriveInput) -> TokenStream {
     let errors = &Errors::default();
-    if input.generics.params.len() != 0 {
+    if !input.generics.params.is_empty() {
         errors.err(
             &input.generics,
             "`#![derive(FromArgs)]` cannot be applied to types with generic parameters",
@@ -65,22 +65,15 @@ enum Optionality {
 impl PartialEq<Optionality> for Optionality {
     fn eq(&self, other: &Optionality) -> bool {
         use Optionality::*;
-        match (self, other) {
-            (None, None) | (Optional, Optional) | (Repeating, Repeating) => true,
-            // NB: (Defaulted, Defaulted) can't contain the same token streams
-            _ => false,
-        }
+        // NB: (Defaulted, Defaulted) can't contain the same token streams
+        matches!((self, other), (Optional, Optional) | (Repeating, Repeating))
     }
 }
 
 impl Optionality {
     /// Whether or not this is `Optionality::None`
     fn is_required(&self) -> bool {
-        if let Optionality::None = self {
-            true
-        } else {
-            false
-        }
+        matches!(self, Optionality::None)
     }
 }
 
@@ -252,6 +245,7 @@ fn impl_from_args_struct(
     let top_or_sub_cmd_impl = top_or_sub_cmd_impl(errors, name, type_attrs);
 
     let trait_impl = quote_spanned! { impl_span =>
+        #[automatically_derived]
         impl argh::FromArgs for #name {
             #from_args_method
 
@@ -269,8 +263,8 @@ fn impl_from_args_struct_from_args<'a>(
     type_attrs: &TypeAttrs,
     fields: &'a [StructField<'a>],
 ) -> TokenStream {
-    let init_fields = declare_local_storage_for_from_args_fields(&fields);
-    let unwrap_fields = unwrap_from_args_fields(&fields);
+    let init_fields = declare_local_storage_for_from_args_fields(fields);
+    let unwrap_fields = unwrap_from_args_fields(fields);
     let positional_fields: Vec<&StructField<'_>> =
         fields.iter().filter(|field| field.kind == FieldKind::Positional).collect();
     let positional_field_idents = positional_fields.iter().map(|field| &field.field.ident);
@@ -289,13 +283,13 @@ fn impl_from_args_struct_from_args<'a>(
         }
     });
 
-    let flag_str_to_output_table_map = flag_str_to_output_table_map_entries(&fields);
+    let flag_str_to_output_table_map = flag_str_to_output_table_map_entries(fields);
 
     let mut subcommands_iter =
         fields.iter().filter(|field| field.kind == FieldKind::SubCommand).fuse();
 
     let subcommand: Option<&StructField<'_>> = subcommands_iter.next();
-    while let Some(dup_subcommand) = subcommands_iter.next() {
+    for dup_subcommand in subcommands_iter {
         errors.duplicate_attrs("subcommand", subcommand.unwrap().field, dup_subcommand.field);
     }
 
@@ -304,7 +298,7 @@ fn impl_from_args_struct_from_args<'a>(
     let missing_requirements_ident = syn::Ident::new("__missing_requirements", impl_span);
 
     let append_missing_requirements =
-        append_missing_requirements(&missing_requirements_ident, &fields);
+        append_missing_requirements(&missing_requirements_ident, fields);
 
     let parse_subcommands = if let Some(subcommand) = subcommand {
         let name = subcommand.name;
@@ -324,12 +318,14 @@ fn impl_from_args_struct_from_args<'a>(
 
     // Identifier referring to a value containing the name of the current command as an `&[&str]`.
     let cmd_name_str_array_ident = syn::Ident::new("__cmd_name", impl_span);
-    let help = help::help(errors, cmd_name_str_array_ident, type_attrs, &fields, subcommand);
+    let help = help::help(errors, cmd_name_str_array_ident, type_attrs, fields, subcommand);
 
     let method_impl = quote_spanned! { impl_span =>
         fn from_args(__cmd_name: &[&str], __args: &[&str])
             -> std::result::Result<Self, argh::EarlyExit>
         {
+            #![allow(clippy::unwrap_in_result)]
+
             #( #init_fields )*
 
             argh::parse_struct_args(
@@ -374,8 +370,8 @@ fn impl_from_args_struct_redact_arg_values<'a>(
     type_attrs: &TypeAttrs,
     fields: &'a [StructField<'a>],
 ) -> TokenStream {
-    let init_fields = declare_local_storage_for_redacted_fields(&fields);
-    let unwrap_fields = unwrap_redacted_fields(&fields);
+    let init_fields = declare_local_storage_for_redacted_fields(fields);
+    let unwrap_fields = unwrap_redacted_fields(fields);
 
     let positional_fields: Vec<&StructField<'_>> =
         fields.iter().filter(|field| field.kind == FieldKind::Positional).collect();
@@ -395,13 +391,13 @@ fn impl_from_args_struct_redact_arg_values<'a>(
         }
     });
 
-    let flag_str_to_output_table_map = flag_str_to_output_table_map_entries(&fields);
+    let flag_str_to_output_table_map = flag_str_to_output_table_map_entries(fields);
 
     let mut subcommands_iter =
         fields.iter().filter(|field| field.kind == FieldKind::SubCommand).fuse();
 
     let subcommand: Option<&StructField<'_>> = subcommands_iter.next();
-    while let Some(dup_subcommand) = subcommands_iter.next() {
+    for dup_subcommand in subcommands_iter {
         errors.duplicate_attrs("subcommand", subcommand.unwrap().field, dup_subcommand.field);
     }
 
@@ -410,7 +406,7 @@ fn impl_from_args_struct_redact_arg_values<'a>(
     let missing_requirements_ident = syn::Ident::new("__missing_requirements", impl_span);
 
     let append_missing_requirements =
-        append_missing_requirements(&missing_requirements_ident, &fields);
+        append_missing_requirements(&missing_requirements_ident, fields);
 
     let redact_subcommands = if let Some(subcommand) = subcommand {
         let name = subcommand.name;
@@ -428,15 +424,15 @@ fn impl_from_args_struct_redact_arg_values<'a>(
         quote_spanned! { impl_span => None }
     };
 
-    let cmd_name = if type_attrs.is_subcommand.is_none() {
-        quote! { __cmd_name.last().expect("no command name").to_string() }
+    let unwrap_cmd_name_err_string = if type_attrs.is_subcommand.is_none() {
+        quote! { "no command name" }
     } else {
-        quote! { __cmd_name.last().expect("no subcommand name").to_string() }
+        quote! { "no subcommand name" }
     };
 
     // Identifier referring to a value containing the name of the current command as an `&[&str]`.
     let cmd_name_str_array_ident = syn::Ident::new("__cmd_name", impl_span);
-    let help = help::help(errors, cmd_name_str_array_ident, type_attrs, &fields, subcommand);
+    let help = help::help(errors, cmd_name_str_array_ident, type_attrs, fields, subcommand);
 
     let method_impl = quote_spanned! { impl_span =>
         fn redact_arg_values(__cmd_name: &[&str], __args: &[&str]) -> std::result::Result<Vec<String>, argh::EarlyExit> {
@@ -471,7 +467,11 @@ fn impl_from_args_struct_redact_arg_values<'a>(
             #missing_requirements_ident.err_on_any()?;
 
             let mut __redacted = vec![
-                #cmd_name,
+                if let Some(cmd_name) = __cmd_name.last() {
+                    (*cmd_name).to_owned()
+                } else {
+                    return Err(argh::EarlyExit::from(#unwrap_cmd_name_err_string.to_owned()));
+                }
             ];
 
             #( #unwrap_fields )*
@@ -510,6 +510,7 @@ fn top_or_sub_cmd_impl(errors: &Errors, name: &syn::Ident, type_attrs: &TypeAttr
     if type_attrs.is_subcommand.is_none() {
         // Not a subcommand
         quote! {
+            #[automatically_derived]
             impl argh::TopLevelCommand for #name {}
         }
     } else {
@@ -519,6 +520,7 @@ fn top_or_sub_cmd_impl(errors: &Errors, name: &syn::Ident, type_attrs: &TypeAttr
             &empty_str
         });
         quote! {
+            #[automatically_derived]
             impl argh::SubCommand for #name {
                 const COMMAND: &'static argh::CommandInfo = &argh::CommandInfo {
                     name: #subcommand_name,
@@ -586,7 +588,9 @@ fn unwrap_from_args_fields<'a>(
         let field_name = field.name;
         match field.kind {
             FieldKind::Option | FieldKind::Positional => match &field.optionality {
-                Optionality::None => quote! { #field_name: #field_name.slot.unwrap() },
+                Optionality::None => quote! {
+                    #field_name: #field_name.slot.unwrap()
+                },
                 Optionality::Optional | Optionality::Repeating => {
                     quote! { #field_name: #field_name.slot }
                 }
@@ -639,7 +643,7 @@ fn declare_local_storage_for_redacted_fields<'a>(
                     let mut #field_name: argh::ParseValueSlotTy::<#field_slot_type, String> =
                         argh::ParseValueSlotTy {
                         slot: std::default::Default::default(),
-                        parse_func: |arg, _| { Ok(arg.to_string()) },
+                        parse_func: |arg, _| { Ok(arg.to_owned()) },
                     };
                 }
             }
@@ -658,7 +662,7 @@ fn declare_local_storage_for_redacted_fields<'a>(
                     let mut #field_name: argh::ParseValueSlotTy::<#field_slot_type, String> =
                         argh::ParseValueSlotTy {
                         slot: std::default::Default::default(),
-                        parse_func: |_, _| { Ok(#arg_name.to_string()) },
+                        parse_func: |_, _| { Ok(#arg_name.to_owned()) },
                     };
                 }
             }
@@ -861,7 +865,12 @@ fn impl_from_args_enum(
             fn from_args(command_name: &[&str], args: &[&str])
                 -> std::result::Result<Self, argh::EarlyExit>
             {
-                let subcommand_name = *command_name.last().expect("no subcommand name");
+                let subcommand_name = if let Some(subcommand_name) = command_name.last() {
+                    *subcommand_name
+                } else {
+                    return Err(argh::EarlyExit::from("no subcommand name".to_owned()));
+                };
+
                 #(
                     if subcommand_name == <#variant_ty as argh::SubCommand>::COMMAND.name {
                         return Ok(#name_repeating::#variant_names(
@@ -869,17 +878,24 @@ fn impl_from_args_enum(
                         ));
                     }
                 )*
-                unreachable!("no subcommand matched")
+
+                Err(argh::EarlyExit::from("no subcommand matched".to_owned()))
             }
 
             fn redact_arg_values(command_name: &[&str], args: &[&str]) -> std::result::Result<Vec<String>, argh::EarlyExit> {
-                let subcommand_name = *command_name.last().expect("no subcommand name");
+                let subcommand_name = if let Some(subcommand_name) = command_name.last() {
+                    *subcommand_name
+                } else {
+                    return Err(argh::EarlyExit::from("no subcommand name".to_owned()));
+                };
+
                 #(
                     if subcommand_name == <#variant_ty as argh::SubCommand>::COMMAND.name {
                         return <#variant_ty as argh::FromArgs>::redact_arg_values(command_name, args);
                     }
                 )*
-                unreachable!("no subcommand matched")
+
+                Err(argh::EarlyExit::from("no subcommand matched".to_owned()))
             }
         }
 
diff --git a/argh_derive/src/parse_attrs.rs b/argh_derive/src/parse_attrs.rs
index 83807ed..33e18b5 100644
--- a/argh_derive/src/parse_attrs.rs
+++ b/argh_derive/src/parse_attrs.rs
@@ -79,29 +79,29 @@ impl FieldAttrs {
 
                 let name = meta.path();
                 if name.is_ident("arg_name") {
-                    if let Some(m) = errors.expect_meta_name_value(&meta) {
+                    if let Some(m) = errors.expect_meta_name_value(meta) {
                         this.parse_attr_arg_name(errors, m);
                     }
                 } else if name.is_ident("default") {
-                    if let Some(m) = errors.expect_meta_name_value(&meta) {
+                    if let Some(m) = errors.expect_meta_name_value(meta) {
                         this.parse_attr_default(errors, m);
                     }
                 } else if name.is_ident("description") {
-                    if let Some(m) = errors.expect_meta_name_value(&meta) {
+                    if let Some(m) = errors.expect_meta_name_value(meta) {
                         parse_attr_description(errors, m, &mut this.description);
                     }
                 } else if name.is_ident("from_str_fn") {
-                    if let Some(m) = errors.expect_meta_list(&meta) {
+                    if let Some(m) = errors.expect_meta_list(meta) {
                         this.parse_attr_from_str_fn(errors, m);
                     }
                 } else if name.is_ident("long") {
-                    if let Some(m) = errors.expect_meta_name_value(&meta) {
+                    if let Some(m) = errors.expect_meta_name_value(meta) {
                         this.parse_attr_long(errors, m);
                     }
                 } else if name.is_ident("option") {
                     parse_attr_field_type(errors, meta, FieldKind::Option, &mut this.field_type);
                 } else if name.is_ident("short") {
-                    if let Some(m) = errors.expect_meta_name_value(&meta) {
+                    if let Some(m) = errors.expect_meta_name_value(meta) {
                         this.parse_attr_short(errors, m);
                     }
                 } else if name.is_ident("subcommand") {
@@ -218,10 +218,8 @@ fn parse_attr_field_type(
     if let Some(path) = errors.expect_meta_word(meta) {
         if let Some(first) = slot {
             errors.duplicate_attrs("field kind", &first.ident, path);
-        } else {
-            if let Some(word) = path.get_ident() {
-                *slot = Some(FieldType { kind, ident: word.clone() });
-            }
+        } else if let Some(word) = path.get_ident() {
+            *slot = Some(FieldType { kind, ident: word.clone() });
         }
     }
 }
@@ -304,28 +302,27 @@ impl TypeAttrs {
 
                 let name = meta.path();
                 if name.is_ident("description") {
-                    if let Some(m) = errors.expect_meta_name_value(&meta) {
+                    if let Some(m) = errors.expect_meta_name_value(meta) {
                         parse_attr_description(errors, m, &mut this.description);
                     }
                 } else if name.is_ident("error_code") {
-                    if let Some(m) = errors.expect_meta_list(&meta) {
+                    if let Some(m) = errors.expect_meta_list(meta) {
                         this.parse_attr_error_code(errors, m);
                     }
                 } else if name.is_ident("example") {
-                    if let Some(m) = errors.expect_meta_name_value(&meta) {
+                    if let Some(m) = errors.expect_meta_name_value(meta) {
                         this.parse_attr_example(errors, m);
                     }
                 } else if name.is_ident("name") {
-                    if let Some(m) = errors.expect_meta_name_value(&meta) {
+                    if let Some(m) = errors.expect_meta_name_value(meta) {
                         this.parse_attr_name(errors, m);
                     }
                 } else if name.is_ident("note") {
-                    if let Some(m) = errors.expect_meta_name_value(&meta) {
+                    if let Some(m) = errors.expect_meta_name_value(meta) {
                         this.parse_attr_note(errors, m);
                     }
                 } else if name.is_ident("subcommand") {
-                    if let Some(ident) = errors.expect_meta_word(&meta).and_then(|p| p.get_ident())
-                    {
+                    if let Some(ident) = errors.expect_meta_word(meta).and_then(|p| p.get_ident()) {
                         this.parse_attr_subcommand(errors, ident);
                     }
                 } else {
@@ -498,7 +495,7 @@ pub fn check_enum_type_attrs(errors: &Errors, type_attrs: &TypeAttrs, type_span:
     // Ensure that `#[argh(subcommand)]` is present.
     if is_subcommand.is_none() {
         errors.err_span(
-            type_span.clone(),
+            *type_span,
             concat!(
                 "`#![derive(FromArgs)]` on `enum`s can only be used to enumerate subcommands.\n",
                 "Consider adding `#[argh(subcommand)]` to the `enum` declaration.",


Test patch:
diff --git a/argh/tests/lib.rs b/argh/tests/lib.rs
index fe8c858..e01e6d0 100644
--- a/argh/tests/lib.rs
+++ b/argh/tests/lib.rs
@@ -1,8 +1,16 @@
-#![cfg(test)]
 // Copyright (c) 2020 Google LLC All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// Deny a bunch of uncommon clippy lints to make sure the generated code won't trigger a warning.
+#![deny(
+    clippy::indexing_slicing,
+    clippy::panic_in_result_fn,
+    clippy::str_to_string,
+    clippy::unreachable,
+    clippy::unwrap_in_result
+)]
+
 use {argh::FromArgs, std::fmt::Debug};
 
 #[test]
@@ -154,7 +162,7 @@ fn default_number() {
 fn default_function() {
     const MSG: &str = "hey I just met you";
     fn call_me_maybe() -> String {
-        MSG.to_string()
+        MSG.to_owned()
     }
 
     #[derive(FromArgs)]
@@ -821,7 +829,7 @@ Options:
             help_example,
             HelpExample {
                 force: true,
-                scribble: "fooey".to_string(),
+                scribble: "fooey".to_owned(),
                 really_really_really_long_name_for_pat: false,
                 verbose: false,
                 command: HelpExampleSubCommands::BlowUp(BlowUp { safely: true }),
@@ -1264,7 +1272,7 @@ Options:
   -n, --n           fooey
   --help            display usage information
 "###
-            .to_string(),
+            .to_owned(),
             status: Ok(()),
         }),
     );
@@ -1283,7 +1291,7 @@ fn redact_arg_values_produces_errors_with_bad_arguments() {
     assert_eq!(
         Cmd::redact_arg_values(&["program-name"], &["--n"]),
         Err(argh::EarlyExit {
-            output: "No value provided for option '--n'.\n".to_string(),
+            output: "No value provided for option '--n'.\n".to_owned(),
             status: Err(()),
         }),
     );
@@ -1306,3 +1314,58 @@ fn redact_arg_values_does_not_warn_if_used() {
     let actual = Cmd::redact_arg_values(&["program-name"], &["5"]).unwrap();
     assert_eq!(actual, &["program-name", "speed"]);
 }
+
+#[test]
+fn subcommand_does_not_panic() {
+    #[derive(FromArgs, PartialEq, Debug)]
+    #[argh(subcommand)]
+    enum SubCommandEnum {
+        Cmd(SubCommand),
+    }
+
+    #[derive(FromArgs, PartialEq, Debug)]
+    /// First subcommand.
+    #[argh(subcommand, name = "one")]
+    struct SubCommand {
+        #[argh(positional)]
+        /// how many x
+        x: usize,
+    }
+
+    #[derive(FromArgs, PartialEq, Debug)]
+    /// Second subcommand.
+    #[argh(subcommand, name = "two")]
+    struct SubCommandTwo {
+        #[argh(switch)]
+        /// whether to fooey
+        fooey: bool,
+    }
+
+    // Passing no subcommand name to an emum
+    assert_eq!(
+        SubCommandEnum::from_args(&[], &["5"]).unwrap_err(),
+        argh::EarlyExit { output: "no subcommand name".into(), status: Err(()) },
+    );
+
+    assert_eq!(
+        SubCommandEnum::redact_arg_values(&[], &["5"]).unwrap_err(),
+        argh::EarlyExit { output: "no subcommand name".into(), status: Err(()) },
+    );
+
+    // Passing unknown subcommand name to an emum
+    assert_eq!(
+        SubCommandEnum::from_args(&["fooey"], &["5"]).unwrap_err(),
+        argh::EarlyExit { output: "no subcommand matched".into(), status: Err(()) },
+    );
+
+    assert_eq!(
+        SubCommandEnum::redact_arg_values(&["fooey"], &["5"]).unwrap_err(),
+        argh::EarlyExit { output: "no subcommand matched".into(), status: Err(()) },
+    );
+
+    // Passing unknown subcommand name to a struct
+    assert_eq!(
+        SubCommand::redact_arg_values(&[], &["5"]).unwrap_err(),
+        argh::EarlyExit { output: "no subcommand name".into(), status: Err(()) },
+    );
+}