additional changes to the 404 mechanism based on feedback:

 - removed config output_404
 - ensure serve overrides the site url, and hosts the correct 404 file
 - refactor 404 rendering into separate fn
 - formatting

1 files changed, 10 insertions, 6 deletions

diff --git a/src/config.rs b/src/config.rs
index b955e352..f6825c39 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -507,10 +507,8 @@ pub struct HtmlConfig {
     /// FontAwesome icon class to use for the Git repository link.
     /// Defaults to `fa-github` if `None`.
     pub git_repository_icon: Option<String>,
-    /// Input path for the 404 file, defaults to 404.md
+    /// Input path for the 404 file, defaults to 404.md, set to "" to disable 404 file output
     pub input_404: Option<String>,
-    /// Output path for 404.html file, defaults to 404.html, set to "" to disable 404 file output
-    pub output_404: Option<String>,
     /// Absolute url to site, used to emit correct paths for the 404 page, which might be accessed in a deeply nested directory
     pub site_url: Option<String>,
     /// This is used as a bit of a workaround for the `mdbook serve` command.
@@ -545,7 +543,6 @@ impl Default for HtmlConfig {
             git_repository_url: None,
             git_repository_icon: None,
             input_404: None,
-            output_404: None,
             site_url: None,
             livereload_url: None,
             redirect: HashMap::new(),
@@ -679,6 +676,7 @@ impl<'de, T> Updateable<'de> for T where T: Serialize + Deserialize<'de> {}
 #[cfg(test)]
 mod tests {
     use super::*;
+    use crate::utils::fs::get_404_output_file;
 
     const COMPLEX_CONFIG: &str = r#"
         [book]
@@ -1024,7 +1022,10 @@ mod tests {
         let got = Config::from_str(src).unwrap();
         let html_config = got.html_config().unwrap();
         assert_eq!(html_config.input_404, None);
-        assert_eq!(html_config.output_404, None);
+        assert_eq!(
+            &get_404_output_file(html_config.input_404.as_deref()),
+            "404.html"
+        );
     }
 
     #[test]
@@ -1038,6 +1039,9 @@ mod tests {
         let got = Config::from_str(src).unwrap();
         let html_config = got.html_config().unwrap();
         assert_eq!(html_config.input_404, Some("missing.md".to_string()));
-        assert_eq!(html_config.output_404, Some("missing.html".to_string()));
+        assert_eq!(
+            &get_404_output_file(html_config.input_404.as_deref()),
+            "missing.html"
+        );
     }
 }