Handle failure to open input file

src/main.rs

@@ -1,5 +1,6 @@
 use std::fs::File;
 use std::io::{self, Read, Write};
+use std::process;
 use structopt::StructOpt;
 
 #[macro_use]
@@ -17,7 +18,14 @@ fn main() {
     let config = Config::new(opt);
 
     let read = match &config.opt.input {
-        Some(f) => Box::new(File::open(f).expect("Could not open file")) as Box<dyn Read>,
+        Some(f) => match File::open(f) {
+            Ok(fh) => Box::new(fh) as Box<dyn Read>,
+            Err(e) => {
+                eprintln!("Failed to open file: {}", e);
+                // exit code of 3 means failure to open input file
+                process::exit(3);
+            }
+        },
         None => Box::new(io::stdin()) as Box<dyn Read>,
     };
 

test/e2e_test.sh

@@ -33,6 +33,17 @@ if [ $r -ne 2 ]; then
   exit 1
 fi
 
+file=/tmp/000_file
+touch $file
+chmod 000 $file
+cargo run -- 3 -i $file >&/dev/null
+r=$?
+if [ $r -ne 3 ]; then
+  echo "Failed to return 3 on file open error"
+  exit 1
+fi
+rm -f $file
+
 cd $orig_dir
 
 printf "\033[1;32mAll tests passed\033[0m\n"