Add test for enum item tuple fields documentation

Author: GuillaumeGomez

src/test/rustdoc-ui/coverage/enums.stdout

@@ -1,7 +1,7 @@
 +-------------------------------------+------------+------------+------------+------------+
 | File                                | Documented | Percentage |   Examples | Percentage |
 +-------------------------------------+------------+------------+------------+------------+
-| ...est/rustdoc-ui/coverage/enums.rs |          6 |      75.0% |          0 |       0.0% |
+| ...est/rustdoc-ui/coverage/enums.rs |          6 |      66.7% |          0 |       0.0% |
 +-------------------------------------+------------+------------+------------+------------+
-| Total                               |          6 |      75.0% |          0 |       0.0% |
+| Total                               |          6 |      66.7% |          0 |       0.0% |
 +-------------------------------------+------------+------------+------------+------------+

src/test/rustdoc/toggle-item-contents.rs

@@ -81,8 +81,8 @@ pub enum EnumStructVariant {
 }
 
 // @has 'toggle_item_contents/enum.LargeEnum.html'
-// @count - '//details[@class="rustdoc-toggle type-contents-toggle"]' 1
-// @has - '//details[@class="rustdoc-toggle type-contents-toggle"]' 'Show 13 variants'
+// @count - '//*[@class="rust enum"]//details[@class="rustdoc-toggle type-contents-toggle"]' 1
+// @has - '//*[@class="rust enum"]//details[@class="rustdoc-toggle type-contents-toggle"]' 'Show 13 variants'
 pub enum LargeEnum {
     A, B, C, D, E, F(u8), G, H, I, J, K, L, M
 }

src/test/rustdoc/tuple-struct-fields-doc.rs

@@ -17,3 +17,20 @@ pub struct Foo(
     /// not hello
     pub i8,
 );
+
+// @has foo/enum.Bar.html
+// @has - '//pre[@class="rust enum"]' 'BarVariant(String),'
+// @matches - '//*[@id="variant.BarVariant.fields"]/h3' '^Tuple Fields of BarVariant$'
+// @has - '//*[@id="variant.BarVariant.field.0"]' '0: String'
+// @has - '//*[@id="variant.BarVariant.fields"]//*[@class="docblock"]' 'Hello docs'
+// @matches - '//*[@id="variant.FooVariant.fields"]/h3' '^Fields of FooVariant$'
+pub enum Bar {
+    BarVariant(
+        /// Hello docs
+        String
+    ),
+    FooVariant {
+       /// hello
+       x: u32,
+    },
+}