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use std::io; use std::fmt; use std::error; pub type Result<T> = std::result::Result<T, Error>; #[derive(Debug)] pub enum Error { LineParse(String, usize), Io(io::Error), EnvVar(std::env::VarError), #[doc(hidden)] __Nonexhaustive } impl Error { pub fn not_found(&self) -> bool { if let Error::Io(ref io_error) = *self { return io_error.kind() == io::ErrorKind::NotFound; } false } } impl error::Error for Error { fn source(&self) -> Option<&(dyn error::Error + 'static)> { match self { Error::Io(err) => Some(err), Error::EnvVar(err) => Some(err), _ => None, } } } impl fmt::Display for Error { fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result { match self { Error::Io(err) => write!(fmt, "{}", err), Error::EnvVar(err) => write!(fmt, "{}", err), Error::LineParse(line, error_index) => write!(fmt, "Error parsing line: '{}', error at line index: {}", line, error_index), _ => unreachable!(), } } } #[cfg(test)] mod test { use std::error::Error as StdError; use super::*; #[test] fn test_io_error_source() { let err = Error::Io(std::io::ErrorKind::PermissionDenied.into()); let io_err = err.source().unwrap().downcast_ref::<std::io::Error>().unwrap(); assert_eq!(std::io::ErrorKind::PermissionDenied, io_err.kind()); } #[test] fn test_envvar_error_source() { let err = Error::EnvVar(std::env::VarError::NotPresent); let var_err = err.source().unwrap().downcast_ref::<std::env::VarError>().unwrap(); assert_eq!(&std::env::VarError::NotPresent, var_err); } #[test] fn test_lineparse_error_source() { let err = Error::LineParse("test line".to_string(), 2); assert!(err.source().is_none()); } #[test] fn test_error_not_found_true() { let err = Error::Io(std::io::ErrorKind::NotFound.into()); assert!(err.not_found()); } #[test] fn test_error_not_found_false() { let err = Error::Io(std::io::ErrorKind::PermissionDenied.into()); assert!(!err.not_found()); } #[test] fn test_io_error_display() { let err = Error::Io(std::io::ErrorKind::PermissionDenied.into()); let io_err: std::io::Error = std::io::ErrorKind::PermissionDenied.into(); let err_desc = format!("{}", err); let io_err_desc = format!("{}", io_err); assert_eq!(io_err_desc, err_desc); } #[test] fn test_envvar_error_display() { let err = Error::EnvVar(std::env::VarError::NotPresent); let var_err = std::env::VarError::NotPresent; let err_desc = format!("{}", err); let var_err_desc = format!("{}", var_err); assert_eq!(var_err_desc, err_desc); } #[test] fn test_lineparse_error_display() { let err = Error::LineParse("test line".to_string(), 2); let err_desc = format!("{}", err); assert_eq!("Error parsing line: 'test line', error at line index: 2", err_desc); } }