feat: different exit codes for different errors

Resolves #292

Author: KSXGitHub

src/lib.rs

@@ -17,7 +17,7 @@ pub mod runtime_error;
 pub fn main() -> std::process::ExitCode {
     if let Err(error) = app::App::from_env().run() {
         eprintln!("[error] {error}");
-        return std::process::ExitCode::FAILURE;
+        return error.code();
     }
     std::process::ExitCode::SUCCESS
 }

src/runtime_error.rs

@@ -1,5 +1,5 @@
 use derive_more::{Display, Error};
-use std::convert::Infallible;
+use std::{convert::Infallible, process::ExitCode};
 
 /// Error caused by the CLI program.
 #[derive(Debug, Display, Error)]
@@ -39,3 +39,16 @@ impl From<Infallible> for RuntimeError {
         match value {}
     }
 }
+
+impl RuntimeError {
+    /// Convert error into exit code.
+    pub fn code(&self) -> ExitCode {
+        ExitCode::from(match self {
+            RuntimeError::SerializationFailure(_) => 2,
+            RuntimeError::DeserializationFailure(_) => 3,
+            RuntimeError::JsonInputArgConflict => 4,
+            RuntimeError::InvalidInputReflection(_) => 5,
+            RuntimeError::UnsupportedFeature(_) => 6,
+        })
+    }
+}