feat(protocol: Severity is now optional

src/protocol.rs

@@ -22,7 +22,11 @@ pub trait Diagnostic: std::error::Error {
 
     /// Diagnostic severity. This may be used by [DiagnosticReporter]s to change the
     /// display format of this diagnostic.
-    fn severity(&self) -> Severity;
+    ///
+    /// If `None`, reporters should treat this as [Severity::Error]
+    fn severity(&self) -> Option<Severity> {
+        None
+    }
 
     /// Additional help text related to this Diagnostic. Do you have any
     /// advice for the poor soul who's just run into this issue?

src/reporter.rs

@@ -103,9 +103,9 @@ impl DiagnosticReporter for MietteReporter {
         }
 
         let sev = match diagnostic.severity() {
-            Severity::Error => "Error",
-            Severity::Warning => "Warning",
-            Severity::Advice => "Advice",
+            Some(Severity::Error) | None => "Error",
+            Some(Severity::Warning) => "Warning",
+            Some(Severity::Advice) => "Advice",
         };
         write!(f, "{}[{}]: {}", sev, diagnostic.code(), diagnostic)?;
 
@@ -151,9 +151,9 @@ impl DiagnosticReporter for JokeReporter {
         }
 
         let sev = match diagnostic.severity() {
-            Severity::Error => "error",
-            Severity::Warning => "warning",
-            Severity::Advice => "advice",
+            Some(Severity::Error) | None => "error",
+            Some(Severity::Warning) => "warning",
+            Some(Severity::Advice) => "advice",
         };
         writeln!(
             f,

tests/reporter.rs

@@ -1,7 +1,8 @@
-use std::fmt;
+use std::{fmt, sync::Arc};
 
 use miette::{
-    Diagnostic, DiagnosticSnippet, DiagnosticReporter, MietteError, MietteReporter, Severity, SourceSpan,
+    Diagnostic, DiagnosticReporter, DiagnosticSnippet, MietteError, MietteReporter,
+    SourceSpan,
 };
 use thiserror::Error;
 
@@ -22,8 +23,6 @@ impl Diagnostic for MyBad {
         &"oops::my::bad"
     }
 
-    fn severity(&self) -> Severity {
-        Severity::Error
     }
 
     fn help(&self) -> Option<Box<dyn '_ + Iterator<Item = &'_ str>>> {