Add test

Author: bugadani

src/librustdoc/html/render/tests.rs

@@ -38,3 +38,14 @@ fn test_name_sorting() {
     sorted.sort_by(|&l, r| compare_names(l, r));
     assert_eq!(names, sorted);
 }
+
+#[test]
+fn test_all_types_prints_header_once() {
+    // Regression test for #82477
+    let all_types = AllTypes::new();
+
+    let mut buffer = Buffer::new();
+    all_types.print(&mut buffer);
+
+    assert_eq!(1, buffer.into_inner().matches("List of all items").count());
+}