feat(parsing): give serviceable parsing error details to users (#135)

src/error.rs

@@ -16,7 +16,7 @@ pub enum ErrorKind {
 impl fmt::Display for Error {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self.kind {
-            ErrorKind::Expression(ref expr) => write!(f, "Invalid expression: {}", expr),
+            ErrorKind::Expression(ref expr) => write!(f, "{expr}"),
         }
     }
 }

src/parsing.rs

@@ -18,8 +18,8 @@ impl TryFrom<Cow<'_, str>> for Schedule {
 
     fn try_from(expression: Cow<'_, str>) -> Result<Self, Self::Error> {
         match schedule.parse(&expression) {
-            Ok(schedule_fields) => Ok(Schedule::new(expression.into_owned(), schedule_fields)), // Extract from nom tuple
-            Err(_) => Err(ErrorKind::Expression("Invalid cron expression.".to_owned()).into()), //TODO: Details
+            Ok(schedule_fields) => Ok(Schedule::new(expression.into_owned(), schedule_fields)), // Extract from winnow tuple
+            Err(parse_error) => Err(ErrorKind::Expression(format!("{parse_error}")).into()),
         }
     }
 }

src/schedule.rs

@@ -689,7 +689,9 @@ mod test {
             &[Token::String(
                 "definitively an invalid value for a cron schedule!",
             )],
-            "Invalid expression: Invalid cron expression.",
+            "definitively an invalid value for a cron schedule!\n\
+                ^\n\
+                The 'Seconds' field does not support using names. 'definitively' specified.",
         );
     }