Add GUI tests for comments highlighting in items declaration

tests/rustdoc-gui/item-decl-comment-highlighting.goml

@@ -0,0 +1,73 @@
+// This test checks that comments in item declarations are highlighted.
+go-to: "file://" + |DOC_PATH| + "/test_docs/private/enum.Enum.html"
+show-text: true
+
+define-function: (
+    "check-item-decl-comment",
+    (theme, url, comment_color),
+    block {
+        go-to: |url|
+        set-local-storage: {"rustdoc-theme": |theme|, "rustdoc-use-system-theme": "false"}
+        reload:
+        assert-css: (".item-decl .comment", {"color": |comment_color|}, ALL)
+    }
+)
+
+define-function: (
+    "check-items-for-theme",
+    (theme, comment_color),
+    block {
+        call-function: ("check-item-decl-comment", {
+            "theme": |theme|,
+            "url": "file://" + |DOC_PATH| + "/test_docs/private/enum.Enum.html",
+            "comment_color": |comment_color|,
+        })
+        call-function: ("check-item-decl-comment", {
+            "theme": |theme|,
+            "url": "file://" + |DOC_PATH| + "/test_docs/private/struct.Struct.html",
+            "comment_color": |comment_color|,
+        })
+        call-function: ("check-item-decl-comment", {
+            "theme": |theme|,
+            "url": "file://" + |DOC_PATH| + "/test_docs/private/struct.Tuple.html",
+            "comment_color": |comment_color|,
+        })
+        call-function: ("check-item-decl-comment", {
+            "theme": |theme|,
+            "url": "file://" + |DOC_PATH| + "/test_docs/private/union.Union.html",
+            "comment_color": |comment_color|,
+        })
+        call-function: ("check-item-decl-comment", {
+            "theme": |theme|,
+            "url": "file://" + |DOC_PATH| + "/proc_macro_test/macro.make_answer.html",
+            "comment_color": |comment_color|,
+        })
+        call-function: ("check-item-decl-comment", {
+            "theme": |theme|,
+            "url": "file://" + |DOC_PATH| + "/proc_macro_test/derive.HelperAttr.html",
+            "comment_color": |comment_color|,
+        })
+    }
+)
+
+call-function: (
+    "check-items-for-theme",
+    {
+        "theme": "ayu",
+        "comment_color": "#788797",
+    }
+)
+call-function: (
+    "check-items-for-theme",
+    {
+        "theme": "dark",
+        "comment_color": "#8d8d8b",
+    }
+)
+call-function: (
+    "check-items-for-theme",
+    {
+        "theme": "light",
+        "comment_color": "#8e908c",
+    }
+)

tests/rustdoc-gui/src/proc_macro_test/Cargo.lock

@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "proc_macro_test"
+version = "0.1.0"

tests/rustdoc-gui/src/proc_macro_test/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "proc_macro_test"
+version = "0.1.0"
+edition = "2021"
+
+[lib]
+path = "lib.rs"
+proc-macro = true

tests/rustdoc-gui/src/proc_macro_test/lib.rs

@@ -0,0 +1,11 @@
+use proc_macro::TokenStream;
+
+#[proc_macro]
+pub fn make_answer(_item: TokenStream) -> TokenStream {
+    "fn answer() -> u32 { 42 }".parse().unwrap()
+}
+
+#[proc_macro_derive(HelperAttr, attributes(helper))]
+pub fn derive_helper_attr(_item: TokenStream) -> TokenStream {
+    TokenStream::new()
+}

tests/rustdoc-gui/src/test_docs/lib.rs

@@ -593,3 +593,21 @@ pub mod foreign_impl_order {
         fn f(&mut self, fg: [u8; 3]) {}
     }
 }
+
+pub mod private {
+    pub struct Tuple(u32, u8);
+    pub struct Struct {
+        a: u8,
+    }
+
+    pub union Union {
+        a: u8,
+        b: u16,
+    }
+
+    pub enum Enum {
+        A,
+        #[doc(hidden)]
+        B,
+    }
+}