refactor: return an exit code from main

src/main.rs

@@ -1,9 +1,11 @@
+use std::process::ExitCode;
+
 use ahab::{cli, command_builder, scripts};
 
 use anyhow::Result;
 use clap::Parser;
 
-fn main() -> Result<()> {
+fn main() -> ExitCode {
     let args = cli::Ahab::parse();
 
     command_builder::set_options(command_builder::Options {
@@ -11,26 +13,49 @@ fn main() -> Result<()> {
         dry_run: args.dry_run,
     });
 
-    match args.command {
-        cli::Commands::Django { command } => match command {
-            cli::Django::Bash => scripts::django::bash(),
-            cli::Django::Run { rest } => scripts::django::run(&rest),
-            cli::Django::MakeCommand { app, name } => scripts::django::make_command(&app, &name),
-            cli::Django::Makemigrations => scripts::django::makemigrations(),
-            cli::Django::Manage { rest } => scripts::django::manage(&rest),
-            cli::Django::Migrate { rest } => scripts::django::migrate(&rest),
-            cli::Django::Shell => scripts::django::shell(),
-            cli::Django::Test => scripts::django::test(),
-        },
-        cli::Commands::Postgres { command } => match command {
-            cli::Postgres::Import { path } => scripts::postgres::import(&path),
-            cli::Postgres::Dump { path, format, gzip } => {
-                scripts::postgres::dump(&path, format, gzip)
-            }
-        },
+    match run(args.command) {
+        Ok(code) => code,
+        Err(e) => {
+            eprintln!("Error: {e:#}");
+            ExitCode::FAILURE
+        }
+    }
+}
+
+fn run(command: cli::Commands) -> Result<ExitCode> {
+    let done = ExitCode::SUCCESS;
+
+    match command {
+        cli::Commands::Django { command } => {
+            match command {
+                cli::Django::Bash => scripts::django::bash(),
+                cli::Django::Run { rest } => scripts::django::run(&rest),
+                cli::Django::MakeCommand { app, name } => {
+                    scripts::django::make_command(&app, &name)
+                }
+                cli::Django::Makemigrations => scripts::django::makemigrations(),
+                cli::Django::Manage { rest } => scripts::django::manage(&rest),
+                cli::Django::Migrate { rest } => scripts::django::migrate(&rest),
+                cli::Django::Shell => scripts::django::shell(),
+                cli::Django::Test => scripts::django::test(),
+            }?;
+
+            Ok(done)
+        }
+        cli::Commands::Postgres { command } => {
+            match command {
+                cli::Postgres::Import { path } => scripts::postgres::import(&path),
+                cli::Postgres::Dump { path, format, gzip } => {
+                    scripts::postgres::dump(&path, format, gzip)
+                }
+            }?;
+
+            Ok(done)
+        }
         cli::Commands::Link { command } => match command {
-            cli::Link::Add { paths, force } => scripts::link::add(&paths, force),
-            cli::Link::Restore { paths, all } => scripts::link::restore(&paths, all),
+            cli::Link::Add { paths, force } => scripts::link::add(&paths, force).map(|()| done),
+            cli::Link::Restore { paths, all } => scripts::link::restore(&paths, all).map(|()| done),
+            // the one command with something to say through its exit code
             cli::Link::Check {
                 paths,
                 porcelain,
@@ -38,6 +63,10 @@ fn main() -> Result<()> {
                 exit_code,
             } => scripts::link::check(&paths, porcelain, null, exit_code),
         },
-        cli::Commands::Completions { shell } => scripts::completions::completions(shell),
+        cli::Commands::Completions { shell } => {
+            scripts::completions::completions(shell)?;
+
+            Ok(done)
+        }
     }
 }

src/scripts/link.rs

@@ -2,11 +2,10 @@ use std::cell::Cell;
 use std::env;
 use std::ffi::OsString;
 use std::fs;
-use std::io::{self, Write};
 use std::os::unix::fs::symlink;
 use std::path::{Path, PathBuf};
-use std::process;
 use std::process::Command;
+use std::process::ExitCode;
 
 use anyhow::{Context, Result, anyhow, bail};
 
@@ -179,7 +178,7 @@ fn warn(msg: impl std::fmt::Display) {
 }
 
 // list untracked paths not in the store, i.e. what a sandbox can still read
-pub fn check(paths: &[PathBuf], porcelain: bool, null: bool, exit_code: bool) -> Result<()> {
+pub fn check(paths: &[PathBuf], porcelain: bool, null: bool, exit_code: bool) -> Result<ExitCode> {
     let repo = Repo::discover()?;
     let pathspecs = relative_pathspecs(&repo, paths)?;
 
@@ -208,11 +207,10 @@ pub fn check(paths: &[PathBuf], porcelain: bool, null: bool, exit_code: bool) ->
 
     // git's --exit-code convention: nothing to report is 0, anything is 1
     if exit_code && !exposed.is_empty() {
-        io::stdout().flush().context("writing the listing")?;
-        process::exit(1);
+        return Ok(ExitCode::FAILURE);
     }
 
-    Ok(())
+    Ok(ExitCode::SUCCESS)
 }
 
 fn print_porcelain(exposed: &[Exposed], null: bool) {