feature: expose --help from rails

src/docker_client.rs

@@ -50,4 +50,18 @@ impl DockerClient {
 
         command
     }
+
+    pub fn get_help(ruby_version: &str, rails_version: &str) -> Command {
+        let mut command = Command::new("docker");
+
+        command
+            .arg("run")
+            .arg("--rm")
+            .arg(format!("rails-new-{}-{}", ruby_version, rails_version))
+            .arg("rails")
+            .arg("new")
+            .arg("--help");
+
+        command
+    }
 }

src/main.rs

@@ -3,8 +3,8 @@
 // use std::process::Command;
 mod docker_client;
 mod rails_new;
-use rails_new::Cli;
-use std::io::Write;
+use rails_new::{Cli, Commands};
+use std::{io::Write, process::Command};
 
 use clap::Parser;
 
@@ -40,10 +40,20 @@ fn main() {
 
     assert!(status.success());
 
-    // Run the image with docker run -v $(pwd):/$(pwd) -w $(pwd) rails-new-$RUBY_VERSION-$RAILS_VERSION rails new $@
-    let status = DockerClient::run_image(&ruby_version, &rails_version, cli.args)
-        .status()
-        .expect("Failed to execute process");
+    let mut command: Command;
+
+    match &cli.command {
+        Some(Commands::RailsHelp {}) => {
+            command = DockerClient::get_help(&ruby_version, &rails_version)
+        }
+
+        None => {
+            // Run the image with docker run -v $(pwd):/$(pwd) -w $(pwd) rails-new-$RUBY_VERSION-$RAILS_VERSION rails new $@
+            command = DockerClient::run_image(&ruby_version, &rails_version, cli.args)
+        }
+    }
+
+    let status = command.status().expect("Failed to execute process");
 
     assert!(status.success());
 }

src/rails_new.rs

@@ -1,7 +1,7 @@
-use clap::Parser;
+use clap::{Parser, Subcommand};
 
 #[derive(Parser)]
-#[command(version, about, long_about = None)]
+#[command(version, about, long_about = None, subcommand_negates_reqs = true)]
 pub struct Cli {
     #[clap(trailing_var_arg = true, required = true)]
     /// arguments passed to `rails new`
@@ -10,6 +10,15 @@ pub struct Cli {
     pub ruby_version: String,
     #[clap(long, short = 'r', default_value = "7.1.3")]
     pub rails_version: String,
+
+    #[command(subcommand)]
+    pub command: Option<Commands>,
+}
+
+#[derive(Subcommand)]
+pub enum Commands {
+    /// Prints `rails new --help`
+    RailsHelp {},
 }
 
 #[cfg(test)]
@@ -35,4 +44,33 @@ mod tests {
 
         Ok(())
     }
+
+    #[test]
+    fn default_values() -> Result<(), Box<dyn std::error::Error>> {
+        use clap::CommandFactory;
+
+        let m = Cli::command().get_matches_from(vec!["rails-new", "my_app"]);
+
+        let ruby_version = m.get_one::<String>("ruby_version").unwrap();
+        let rails_version = m.get_one::<String>("rails_version").unwrap();
+
+        assert_eq!(ruby_version, "3.2.3");
+        assert_eq!(rails_version, "7.1.3");
+
+        Ok(())
+    }
+
+    #[test]
+    fn rails_help() -> Result<(), Box<dyn std::error::Error>> {
+        use clap::CommandFactory;
+
+        let m = Cli::command().get_matches_from(vec!["rails-new", "rails-help"]);
+
+        match m.subcommand_name() {
+            Some("rails-help") => {}
+            _ => panic!("Expected subcommand 'rails-help'"),
+        }
+
+        Ok(())
+    }
 }