Add test for search result keyword extra info

Author: GuillaumeGomez

src/test/rustdoc-gui/search-result-keyword.goml

@@ -0,0 +1,11 @@
+goto: file://|DOC_PATH|/test_docs/index.html
+write: (".search-input", "CookieMonster")
+// Waiting for the search results to appear...
+wait-for: "#titles"
+// Note: The two next assert commands could be merged as one but readability would be
+// less good.
+//
+// Checking that the CSS is displaying " (keyword)"...
+assert: (".result-name span.keyword::after", {"content": '" (keyword)"'})
+// ... in italic.
+assert: (".result-name span.keyword::after", {"font-style": "italic"})

src/test/rustdoc-gui/src/lib.rs

@@ -2,6 +2,7 @@
 //! documentation generated so we can test each different features.
 
 #![crate_name = "test_docs"]
+#![feature(doc_keyword)]
 
 use std::fmt;
 
@@ -91,3 +92,6 @@ pub fn check_list_code_block() {}
 pub enum AnEnum {
     WithVariants { and: usize, sub: usize, variants: usize },
 }
+
+#[doc(keyword = "CookieMonster")]
+pub mod keyword {}