Allow passing command-line arguments into run() (#2173)

src/main.rs

@@ -1,5 +1,5 @@
 fn main() {
-  if let Err(code) = just::run() {
+  if let Err(code) = just::run(std::env::args_os()) {
     std::process::exit(code);
   }
 }

src/run.rs

@@ -2,7 +2,7 @@ use super::*;
 
 /// Main entry point into just binary.
 #[allow(clippy::missing_errors_doc)]
-pub fn run() -> Result<(), i32> {
+pub fn run(args: impl Iterator<Item = impl Into<OsString> + Clone>) -> Result<(), i32> {
   #[cfg(windows)]
   ansi_term::enable_ansi_support().ok();
 
@@ -17,7 +17,7 @@ pub fn run() -> Result<(), i32> {
   let app = Config::app();
 
   info!("Parsing command line arguments…");
-  let matches = app.get_matches();
+  let matches = app.get_matches_from(args);
 
   let config = Config::from_matches(&matches).map_err(Error::from);