Add an integration test for heading attributes

tests/dummy_book/src/SUMMARY.md

@@ -14,6 +14,7 @@
     - [Unicode](first/unicode.md)
     - [No Headers](first/no-headers.md)
     - [Duplicate Headers](first/duplicate-headers.md)
+    - [Heading Attributes](first/heading-attributes.md)
 - [Second Chapter](second.md)
     - [Nested Chapter](second/nested.md)
 

tests/dummy_book/src/first/heading-attributes.md

@@ -0,0 +1,5 @@
+# Heading Attributes {#attrs}
+
+## Heading with classes {.class1 .class2}
+
+## Heading with id and classes {#both .class1 .class2}

tests/rendered_output.rs

@@ -35,6 +35,7 @@ const TOC_SECOND_LEVEL: &[&str] = &[
     "1.5. Unicode",
     "1.6. No Headers",
     "1.7. Duplicate Headers",
+    "1.8. Heading Attributes",
     "2.1. Nested Chapter",
 ];
 
@@ -766,7 +767,7 @@ mod search {
         assert_eq!(docs[&some_section]["body"], "");
         assert_eq!(
             docs[&summary]["body"],
-            "Dummy Book Introduction First Chapter Nested Chapter Includes Recursive Markdown Unicode No Headers Duplicate Headers Second Chapter Nested Chapter Conclusion"
+            "Dummy Book Introduction First Chapter Nested Chapter Includes Recursive Markdown Unicode No Headers Duplicate Headers Heading Attributes Second Chapter Nested Chapter Conclusion"
         );
         assert_eq!(
             docs[&summary]["breadcrumbs"],
@@ -946,3 +947,19 @@ fn custom_fonts() {
         &["fonts.css", "myfont.woff"]
     );
 }
+
+#[test]
+fn custom_header_attributes() {
+    let temp = DummyBook::new().build().unwrap();
+    let md = MDBook::load(temp.path()).unwrap();
+    md.build().unwrap();
+
+    let contents = temp.path().join("book/first/heading-attributes.html");
+
+    let summary_strings = &[
+        r##"<h1 id="attrs"><a class="header" href="#attrs">Heading Attributes</a></h1>"##,
+        r##"<h2 id="heading-with-classes" class="class1 class2"><a class="header" href="#heading-with-classes">Heading with classes</a></h2>"##,
+        r##"<h2 id="both" class="class1 class2"><a class="header" href="#both">Heading with id and classes</a></h2>"##,
+    ];
+    assert_contains_strings(&contents, summary_strings);
+}