Make link to first chapter active in index page

Makes both pages more consistent, and also the previous test pass

Co-authored-by: Eric Huss <eric@huss.org>

src/renderer/html_handlebars/hbs_renderer.rs

@@ -116,7 +116,7 @@ impl HtmlHandlebars {
         if ctx.is_index {
             ctx.data.insert("path".to_owned(), json!("index.md"));
             ctx.data.insert("path_to_root".to_owned(), json!(""));
-            ctx.data.insert("is_index".to_owned(), json!("true"));
+            ctx.data.insert("is_index".to_owned(), json!(true));
             let rendered_index = ctx.handlebars.render("index", &ctx.data)?;
             let rendered_index =
                 self.post_process(rendered_index, &ctx.html_config.playground, ctx.edition);

src/renderer/html_handlebars/helpers/toc.rs

@@ -57,6 +57,11 @@ impl HelperDef for RenderToc {
         out.write("<ol class=\"chapter\">")?;
 
         let mut current_level = 1;
+        // The "index" page, which has this attribute set, is supposed to alias the first chapter in
+        // the book, i.e. the first link. There seems to be no easy way to determine which chapter
+        // the "index" is aliasing from within the renderer, so this is used instead to force the
+        // first link to be active. See further below.
+        let mut is_first_chapter = ctx.data().get("is_index").is_some();
 
         for item in chapters {
             // Spacer
@@ -130,7 +135,8 @@ impl HelperDef for RenderToc {
                 out.write(&tmp)?;
                 out.write("\"")?;
 
-                if path == &current_path {
+                if path == &current_path || is_first_chapter {
+                    is_first_chapter = false;
                     out.write(" class=\"active\"")?;
                 }
 

tests/rendered_output.rs

@@ -15,7 +15,7 @@ use select::predicate::{Class, Name, Predicate};
 use std::collections::HashMap;
 use std::ffi::OsStr;
 use std::fs;
-use std::io::{Read, Write};
+use std::io::Write;
 use std::path::{Component, Path, PathBuf};
 use std::str::FromStr;
 use tempfile::Builder as TempFileBuilder;
@@ -476,23 +476,10 @@ fn first_chapter_is_copied_as_index_even_if_not_first_elem() {
     let md = MDBook::load_with_config(temp.path(), cfg).unwrap();
     md.build().unwrap();
 
-    // In theory, just reading the entire files into memory and comparing is sufficient for *testing*,
-    // but since the files are temporary and get deleted when the test completes, we'll want to print
-    // the differences on failure.
-    // We could invoke `diff` on the files on failure, but that may not be portable (hi, Windows...)
-    // so we'll do the job ourselves—potentially a bit sloppily, but that can always be piped into
-    // `diff` manually afterwards.
-    let book_path = temp.path().join("book");
-    let read_file = |path: &str| {
-        let mut buf = String::new();
-        fs::File::open(book_path.join(path))
-            .with_context(|| format!("Failed to read {}", path))
-            .unwrap()
-            .read_to_string(&mut buf)
-            .unwrap();
-        buf
-    };
-    pretty_assertions::assert_eq!(read_file("chapter_1.html"), read_file("index.html"));
+    let root = temp.path().join("book");
+    let chapter = fs::read_to_string(root.join("chapter_1.html")).expect("read chapter 1");
+    let index = fs::read_to_string(root.join("index.html")).expect("read index");
+    pretty_assertions::assert_eq!(chapter, index);
 }
 
 #[test]