feature: expose --help from rails

src/docker_client.rs

@@ -40,4 +40,18 @@ 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

@@ -3,7 +3,7 @@
 // use std::process::Command;
 mod docker_client;
 mod rails_new;
-use rails_new::Cli;
+use rails_new::{Cli, Commands};
 use std::io::Write;
 
 use clap::Parser;
@@ -34,10 +34,22 @@ 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");
-
-    assert!(status.success());
+    match &cli.command {
+        Some(Commands::RailsHelp {}) => {
+            let mut child = DockerClient::get_help(&ruby_version, &rails_version)
+                .spawn()
+                .expect("Failed to execute process");
+            let status = child.wait().expect("failed to wait on child");
+            assert!(status.success());
+        }
+
+        None => {
+            // 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");
+
+            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 --help`
+    RailsHelp {},
 }
 
 #[test]