A WIP for incorporating testing into crusty, as well as an example echo check function

test.rs

#[test]
fn echo_check() {
    use crate::{ShellState, process_input};
    let mut shell_state = ShellState::init();
    let success = process_input(&mut shell_state, "echo test".to_string());
    assert!(success, "echo test failed!");
}

testing.diff

diff --git a/src/main.rs b/src/main.rs
index a698608..f816aac 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,5 +1,6 @@
 mod builtins;
 mod shared_functions;
+mod test;
 
 #[cfg(feature = "readline")]
 use rustyline::{error::ReadlineError, Editor};
@@ -10,12 +11,12 @@ use std::process::exit;
 use shared_functions::parse_input;
 
 // Process the input to run the appropriate builtin or external command.
-fn process_input(shell_state: &mut ShellState, input: String) {
+fn process_input(shell_state: &mut ShellState, input: String) -> bool {
     if input.is_empty() {
-        return;
+        return false;
     }
     let command = ShellCommand::new(input);
-    ShellCommand::run(shell_state, command);
+    ShellCommand::run(shell_state, command)
 }
 
 #[cfg(feature = "readline")]
diff --git a/src/shared_functions.rs b/src/shared_functions.rs
index a79b280..ea1c6e4 100644
--- a/src/shared_functions.rs
+++ b/src/shared_functions.rs
@@ -63,19 +63,24 @@ impl ShellCommand {
             args: split_input_string[1..].to_vec(),
         }
     }
-    pub fn run(shell_state: &mut ShellState, command: ShellCommand) {
+    pub fn run(shell_state: &mut ShellState, command: ShellCommand) -> bool {
         match command.name.as_str() {
-            "calc" => println!("{}", calc(command.args)),
-            "cd"   => cd(shell_state, command),
-            "echo" => println!("{}", echo(command.args)),
-            "help" => help(),
-            "ls"   => print!("{}", ls(command.args)),
-            "pwd"  => println!("{}", std::env::current_dir().unwrap().display()),
+            "calc" => { println!("{}", calc(command.args)); return true; },
+            "cd"   => { cd(shell_state, command);           return true; },
+            "echo" => { println!("{}", echo(command.args)); return true; },
+            "help" => { help();                             return true; },
+            "ls"   => { print!("{}", ls(command.args));     return true; },
+            "pwd"  => {
+                println!("{}", std::env::current_dir().unwrap().display());
+                return true;
+            },
             _ => {
                 if command.args.contains(&String::from("|")) {
                     piped_cmd(PipedShellCommand::from(command));
+                    return true;
                 } else {
                     cmd(command);
+                    return true;
                 }
             }
         }