Replace structopt by clap (#155)

Cargo.toml

@@ -50,7 +50,7 @@ linked-hash-map = "0.5.3"
 once_cell = { version = "1.8", features = ["parking_lot"] }
 regex = "1.5"
 sealed = "0.3"
-structopt = "0.3.25"
+clap = { version = "3.0.0-rc.4", features = ["derive"]  }
 
 # "macros" feature dependencies.
 cucumber-codegen = { version = "0.11.0-dev", path = "./codegen", optional = true }

src/cli.rs

@@ -27,9 +27,9 @@
 //! [`Writer`]: crate::Writer
 //! [1]: https://cucumber.io/docs/cucumber/api#tag-expressions
 
+use clap::{Args, Parser as ClapParser};
 use gherkin::tagexpr::TagOperation;
 use regex::Regex;
-use structopt::StructOpt;
 
 // Workaround for overwritten doc-comments.
 // https://github.com/TeXitoi/structopt/issues/333#issuecomment-712265332
@@ -47,9 +47,9 @@ and may be extended with custom CLI options additionally.
 # use std::{convert::Infallible, time::Duration};
 #
 # use async_trait::async_trait;
+# use clap::Parser as ClapParser;
 # use cucumber::{cli, WorldInit};
 # use futures::FutureExt as _;
-# use structopt::StructOpt;
 # use tokio::time;
 #
 # #[derive(Debug, WorldInit)]
@@ -66,17 +66,17 @@ and may be extended with custom CLI options additionally.
 #
 # #[tokio::main(flavor = "current_thread")]
 # async fn main() {
-#[derive(StructOpt)]
+#[derive(ClapParser)]
 struct CustomOpts {
     /// Additional time to wait in before hook.
-    #[structopt(
+    #[clap(
         long,
         parse(try_from_str = humantime::parse_duration)
     )]
     pre_pause: Option<Duration>,
 }
 
-let opts = cli::Opts::<_, _, _, CustomOpts>::from_args();
+let opts = cli::Opts::<_, _, _, CustomOpts>::parse();
 let pre_pause = opts.custom.pre_pause.unwrap_or_default();
 
 MyWorld::cucumber()
@@ -94,18 +94,18 @@ MyWorld::cucumber()
 "#
 )]
 #[cfg_attr(not(doc), doc = "Run the tests, pet a dog!.")]
-#[derive(Debug, Clone, StructOpt)]
-#[structopt(name = "cucumber", about = "Run the tests, pet a dog!.")]
+#[derive(Debug, Clone, ClapParser)]
+#[clap(name = "cucumber", about = "Run the tests, pet a dog!.")]
 pub struct Opts<Parser, Runner, Writer, Custom = Empty>
 where
-    Parser: StructOpt,
-    Runner: StructOpt,
-    Writer: StructOpt,
-    Custom: StructOpt,
+    Parser: Args,
+    Runner: Args,
+    Writer: Args,
+    Custom: Args,
 {
     /// Regex to filter scenarios by their name.
-    #[structopt(
-        short = "n",
+    #[clap(
+        short = 'n',
         long = "name",
         name = "regex",
         visible_alias = "scenario-name"
@@ -116,8 +116,8 @@ where
     ///
     /// Note: Tags from Feature, Rule and Scenario are merged together on
     /// filtering, so be careful about conflicting tags on different levels.
-    #[structopt(
-        short = "t",
+    #[clap(
+        short = 't',
         long = "tags",
         name = "tagexpr",
         conflicts_with = "regex"
@@ -127,23 +127,23 @@ where
     /// [`Parser`] CLI options.
     ///
     /// [`Parser`]: crate::Parser
-    #[structopt(flatten)]
+    #[clap(flatten)]
     pub parser: Parser,
 
     /// [`Runner`] CLI options.
     ///
     /// [`Runner`]: crate::Runner
-    #[structopt(flatten)]
+    #[clap(flatten)]
     pub runner: Runner,
 
     /// [`Writer`] CLI options.
     ///
     /// [`Writer`]: crate::Writer
-    #[structopt(flatten)]
+    #[clap(flatten)]
     pub writer: Writer,
 
     /// Additional custom CLI options.
-    #[structopt(flatten)]
+    #[clap(flatten)]
     pub custom: Custom,
 }
 
@@ -154,21 +154,15 @@ where
     not(doc),
     allow(missing_docs, clippy::missing_docs_in_private_items)
 )]
-#[derive(Clone, Copy, Debug, StructOpt)]
-pub struct Empty {
-    /// This field exists only because [`StructOpt`] derive macro doesn't
-    /// support unit structs.
-    #[allow(dead_code)]
-    #[structopt(skip)]
-    skipped: (),
-}
+#[derive(Clone, Copy, Debug, Args)]
+pub struct Empty;
 
 // Workaround for overwritten doc-comments.
 // https://github.com/TeXitoi/structopt/issues/333#issuecomment-712265332
 #[cfg_attr(
     doc,
     doc = r#"
-Composes two [`StructOpt`] derivers together.
+Composes two [`Args`] derivers together.
 
 # Example
 
@@ -177,13 +171,13 @@ another one:
 ```rust
 # use async_trait::async_trait;
 # use cucumber::{cli, event, parser, writer, Event, World, Writer};
-# use structopt::StructOpt;
+# use clap::Args;
 #
 struct CustomWriter<Wr>(Wr);
 
-#[derive(StructOpt)]
+#[derive(Args)]
 struct Cli {
-    #[structopt(long)]
+    #[clap(long)]
     custom_option: Option<String>,
 }
 
@@ -257,18 +251,18 @@ impl<Wr: writer::NonTransforming> writer::NonTransforming
     not(doc),
     allow(missing_docs, clippy::missing_docs_in_private_items)
 )]
-#[derive(Debug, StructOpt)]
-pub struct Compose<L: StructOpt, R: StructOpt> {
-    /// Left [`StructOpt`] deriver.
-    #[structopt(flatten)]
+#[derive(Debug, Args)]
+pub struct Compose<L: Args, R: Args> {
+    /// Left [`Args`] deriver.
+    #[clap(flatten)]
     pub left: L,
 
-    /// Right [`StructOpt`] deriver.
-    #[structopt(flatten)]
+    /// Right [`Args`] deriver.
+    #[clap(flatten)]
     pub right: R,
 }
 
-impl<L: StructOpt, R: StructOpt> Compose<L, R> {
+impl<L: Args, R: Args> Compose<L, R> {
     /// Unpacks this [`Compose`] into the underlying CLIs.
     #[must_use]
     pub fn into_inner(self) -> (L, R) {

src/cucumber.rs

@@ -20,14 +20,13 @@ use std::{
     path::Path,
 };
 
-use futures::{future::LocalBoxFuture, StreamExt as _};
-use regex::Regex;
-use structopt::{StructOpt, StructOptInternal};
-
 use crate::{
     cli, event, parser, runner, step, tag::Ext as _, writer, Event, Parser,
     Runner, ScenarioType, Step, World, Writer, WriterExt as _,
 };
+use clap::{Args, Parser as _};
+use futures::{future::LocalBoxFuture, StreamExt as _};
+use regex::Regex;
 
 /// Top-level [Cucumber] executor.
 ///
@@ -54,7 +53,7 @@ where
     P: Parser<I>,
     R: Runner<W>,
     Wr: Writer<W>,
-    Cli: StructOpt,
+    Cli: Args,
 {
     /// [`Parser`] sourcing [`Feature`]s for execution.
     ///
@@ -88,7 +87,7 @@ where
     P: Parser<I>,
     R: Runner<W>,
     Wr: Writer<W>,
-    Cli: StructOpt,
+    Cli: Args,
 {
     /// Creates a custom [`Cucumber`] executor with the provided [`Parser`],
     /// [`Runner`] and [`Writer`].
@@ -437,7 +436,7 @@ where
     P: Parser<I>,
     R: Runner<W>,
     Wr: Writer<W> + for<'val> writer::Arbitrary<'val, W, String>,
-    Cli: StructOpt,
+    Cli: Args,
 {
     /// Consider [`Skipped`] steps as [`Failed`] if their [`Scenario`] isn't
     /// marked with `@allow.skipped` tag.
@@ -627,7 +626,7 @@ where
     P: Parser<I>,
     R: Runner<W>,
     Wr: Writer<W> + writer::Normalized,
-    Cli: StructOpt + StructOptInternal,
+    Cli: Args,
 {
     /// Runs [`Cucumber`].
     ///
@@ -645,7 +644,7 @@ where
     /// using them inside [`Cucumber`].
     ///
     /// Also, any additional custom CLI options may be specified as a
-    /// [`StructOpt`] deriving type, used as the last type parameter of
+    /// [`Args`] deriving type, used as the last type parameter of
     /// [`cli::Opts`].
     ///
     /// > ⚠️ __WARNING__: Any CLI options of [`Parser`], [`Runner`], [`Writer`]
@@ -658,9 +657,9 @@ where
     /// # use std::{convert::Infallible, time::Duration};
     /// #
     /// # use async_trait::async_trait;
+    /// # use clap::{Args, Parser as _};
     /// # use cucumber::{cli, WorldInit};
     /// # use futures::FutureExt as _;
-    /// # use structopt::StructOpt;
     /// # use tokio::time;
     /// #
     /// # #[derive(Debug, WorldInit)]
@@ -677,17 +676,17 @@ where
     /// #
     /// # #[tokio::main(flavor = "current_thread")]
     /// # async fn main() {
-    /// #[derive(StructOpt)]
+    /// #[derive(Args)]
     /// struct CustomCli {
     ///     /// Additional time to wait in a before hook.
-    ///     #[structopt(
+    ///     #[clap(
     ///         long,
     ///         parse(try_from_str = humantime::parse_duration)
     ///     )]
     ///     before_time: Option<Duration>,
     /// }
     ///
-    /// let cli = cli::Opts::<_, _, _, CustomCli>::from_args();
+    /// let cli = cli::Opts::<_, _, _, CustomCli>::parse();
     /// let time = cli.custom.before_time.unwrap_or_default();
     ///
     /// MyWorld::cucumber()
@@ -719,7 +718,7 @@ where
         cli: cli::Opts<P::Cli, R::Cli, Wr::Cli, CustomCli>,
     ) -> Cucumber<W, P, I, R, Wr, CustomCli>
     where
-        CustomCli: StructOpt,
+        CustomCli: Args,
     {
         let Cucumber {
             parser,
@@ -811,7 +810,7 @@ where
             runner: runner_cli,
             writer: writer_cli,
             ..
-        } = self.cli.unwrap_or_else(cli::Opts::<_, _, _, _>::from_args);
+        } = self.cli.unwrap_or_else(cli::Opts::<_, _, _, _>::parse);
 
         let filter = move |feat: &gherkin::Feature,
                            rule: Option<&gherkin::Rule>,
@@ -884,7 +883,7 @@ where
     P: Debug + Parser<I>,
     R: Debug + Runner<W>,
     Wr: Debug + Writer<W>,
-    Cli: StructOpt,
+    Cli: Args,
 {
     fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
         f.debug_struct("Cucumber")
@@ -954,7 +953,7 @@ where
     W: World,
     R: Runner<W>,
     Wr: Writer<W>,
-    Cli: StructOpt,
+    Cli: Args,
     I: AsRef<Path>,
 {
     /// Sets the provided language of [`gherkin`] files.
@@ -977,7 +976,7 @@ where
     W: World,
     P: Parser<I>,
     Wr: Writer<W>,
-    Cli: StructOpt,
+    Cli: Args,
     F: Fn(
             &gherkin::Feature,
             Option<&gherkin::Rule>,
@@ -1176,7 +1175,7 @@ where
     P: Parser<I>,
     R: Runner<W>,
     Wr: writer::Failure<W> + writer::Normalized,
-    Cli: StructOpt + StructOptInternal,
+    Cli: Args,
 {
     /// Runs [`Cucumber`].
     ///

src/parser/basic.rs

@@ -18,12 +18,12 @@ use std::{
     vec,
 };
 
+use clap::Parser as ClapParser;
 use derive_more::{Display, Error};
 use futures::stream;
 use gherkin::GherkinEnv;
 use globwalk::{GlobWalker, GlobWalkerBuilder};
 use itertools::Itertools as _;
-use structopt::StructOpt;
 
 use crate::feature::Ext as _;
 
@@ -36,11 +36,11 @@ use super::{Error as ParseError, Parser};
     not(doc),
     allow(missing_docs, clippy::missing_docs_in_private_items)
 )]
-#[derive(Debug, StructOpt)]
+#[derive(Debug, ClapParser)]
 pub struct Cli {
     /// Glob pattern to look for feature files with. By default, looks for
     /// `*.feature`s in the path configured tests runner.
-    #[structopt(long = "input", short = "i", name = "glob")]
+    #[clap(long = "input", short = 'i', name = "glob")]
     pub features: Option<Walker>,
 }
 

src/parser/mod.rs

@@ -14,11 +14,10 @@
 
 pub mod basic;
 
-use std::sync::Arc;
-
+use clap::Args;
 use derive_more::{Display, Error};
 use futures::Stream;
-use structopt::StructOptInternal;
+use std::sync::Arc;
 
 use crate::feature::ExpandExamplesError;
 
@@ -38,10 +37,7 @@ pub trait Parser<I> {
     /// [`cli::Empty`]: crate::cli::Empty
     /// [`Runner`]: crate::Runner
     /// [`Writer`]: crate::Writer
-    // We do use `StructOptInternal` here only because `StructOpt::from_args()`
-    // requires exactly this trait bound. We don't touch any `StructOptInternal`
-    // details being a subject of instability.
-    type Cli: StructOptInternal + 'static;
+    type Cli: Args;
 
     /// Output [`Stream`] of parsed [`Feature`]s.
     ///