call first_chapter

src/cmd/watch.rs

@@ -1,3 +1,4 @@
+use crate::first_chapter;
 use crate::{get_book_dir, open};
 use clap::{arg, App, Arg, ArgMatches};
 use mdbook::errors::Result;
@@ -45,7 +46,12 @@ pub fn execute(args: &ArgMatches) -> Result<()> {
 
     if args.is_present("open") {
         book.build()?;
-        open(book.build_dir_for("html").join("index.html"));
+        match first_chapter(&book)
+            .map(|path| book.build_dir_for("html").join(path).with_extension("html"))
+        {
+            Some(path) if Path::new(&path).exists() => open(path),
+            _ => warn!("No chapter available to open"),
+        }
     }
 
     trigger_on_change(&book, |paths, book_dir| {