Chore: Add witness hint for enum_variant_added lint

src/lints/enum_variant_added.ron

@@ -46,6 +46,12 @@ SemverQuery(
                         variant @fold @transform(op: "count") @filter(op: "=", value: ["$zero"]) {
                             name @filter(op: "=", value: ["%variant_name"])
                         }
+
+                        variant @fold {
+                            baseline_variant_kinds: __typename @output
+
+                            baseline_variant_names: name @output
+                        }
                     }
                 }
             }
@@ -59,4 +65,9 @@ SemverQuery(
     },
     error_message: "A publicly-visible enum without #[non_exhaustive] has a new variant.",
     per_result_error_template: Some("variant {{enum_name}}:{{variant_name}} in {{span_filename}}:{{span_begin_line}}"),
+    witness: (
+        hint_template: r#"match value { {{#each baseline_variant_kinds }}
+    {{ join "::" ../path }}::{{lookup ../baseline_variant_names @index}}{{#if (eq this "StructVariant")}} { .. }{{/if}}{{#if (eq this "TupleVariant")}}(..){{/if}} => (),{{/each}}
+}"#,
+    ),
 )

test_crates/enum_variant_added/new/src/lib.rs

@@ -2,6 +2,12 @@
 
 pub enum EnumWithNewVariant {
     OldVariant,
+
+    OldStructVariant {
+        x: i64,
+    },
+
+    OldTupleVariant(i64),
 
     NewVariant,
 }

test_crates/enum_variant_added/old/src/lib.rs

@@ -2,6 +2,12 @@
 
 pub enum EnumWithNewVariant {
     OldVariant,
+
+    OldStructVariant {
+        x: i64,
+    },
+
+    OldTupleVariant(i64)
 }
 
 /// This enum should not be reported by the `enum_variant_added` rule,

test_outputs/query_execution/enum_variant_added.snap

@@ -6,6 +6,12 @@ snapshot_kind: text
 {
   "./test_crates/enum_discriminant_no_longer_defined/": [
     {
+      "baseline_variant_kinds": List([
+        String("PlainVariant"),
+      ]),
+      "baseline_variant_names": List([
+        String("None"),
+      ]),
       "enum_name": String("GainsStructVariant"),
       "path": List([
         String("enum_discriminant_no_longer_defined"),
@@ -20,20 +26,38 @@ snapshot_kind: text
   ],
   "./test_crates/enum_variant_added/": [
     {
+      "baseline_variant_kinds": List([
+        String("PlainVariant"),
+        String("StructVariant"),
+        String("TupleVariant"),
+      ]),
+      "baseline_variant_names": List([
+        String("OldVariant"),
+        String("OldStructVariant"),
+        String("OldTupleVariant"),
+      ]),
       "enum_name": String("EnumWithNewVariant"),
       "path": List([
         String("enum_variant_added"),
         String("EnumWithNewVariant"),
       ]),
-      "span_begin_line": Uint64(6),
-      "span_end_line": Uint64(6),
+      "span_begin_line": Uint64(12),
+      "span_end_line": Uint64(12),
       "span_filename": String("src/lib.rs"),
       "variant_name": String("NewVariant"),
       "visibility_limit": String("public"),
     },
   ],
   "./test_crates/enum_variant_hidden_from_public_api/": [
     {
+      "baseline_variant_kinds": List([
+        String("PlainVariant"),
+        String("PlainVariant"),
+      ]),
+      "baseline_variant_names": List([
+        String("First"),
+        String("Second"),
+      ]),
       "enum_name": String("AddedVariant"),
       "path": List([
         String("enum_variant_hidden_from_public_api"),

test_outputs/witnesses/enum_variant_added.snap

@@ -0,0 +1,32 @@
+---
+source: src/query.rs
+description: "Lint `enum_variant_added` did not have the expected witness output.\nSee https://github.com/obi1kenobi/cargo-semver-checks/blob/main/CONTRIBUTING.md#testing-witnesses\nfor more information."
+expression: "&actual_witnesses"
+snapshot_kind: text
+---
+[["./test_crates/enum_discriminant_no_longer_defined/"]]
+filename = 'src/lib.rs'
+begin_line = 69
+hint = '''
+match value { 
+    enum_discriminant_no_longer_defined::GainsStructVariant::None => (),
+}'''
+
+[["./test_crates/enum_variant_added/"]]
+filename = 'src/lib.rs'
+begin_line = 12
+hint = '''
+match value { 
+    enum_variant_added::EnumWithNewVariant::OldVariant => (),
+    enum_variant_added::EnumWithNewVariant::OldStructVariant { .. } => (),
+    enum_variant_added::EnumWithNewVariant::OldTupleVariant(..) => (),
+}'''
+
+[["./test_crates/enum_variant_hidden_from_public_api/"]]
+filename = 'src/lib.rs'
+begin_line = 18
+hint = '''
+match value { 
+    enum_variant_hidden_from_public_api::AddedVariant::First => (),
+    enum_variant_hidden_from_public_api::AddedVariant::Second => (),
+}'''