Render the theme template files if present

* Change the behavior of the template rendering:
    * Check if the template bare name is present
    * Check if the template is part of a theme
    * Fallback to defaults
* Change the behavior of the shortcode rendering:
    * Call the template rendering function
* Prepend `__zola_builtins/` to most of the default elements in `ZOLA_TERA`
* Add a test to verify the presence and content of a `404.html` page
from a theme's template

components/rendering/src/shortcode.rs

@@ -4,7 +4,7 @@ use regex::Regex;
 use tera::{to_value, Context, Map, Value};
 
 use context::RenderContext;
-use errors::{Result, Error};
+use errors::{Error, Result};
 
 // This include forces recompiling this source file if the grammar file changes.
 // Uncomment it when doing changes to the .pest file
@@ -111,11 +111,11 @@ fn render_shortcode(
         tera_context.insert("body", b.trim_right());
     }
     tera_context.extend(context.tera_context.clone());
-    let tpl_name = format!("shortcodes/{}.html", name);
 
-    let res = context
-        .tera
-        .render(&tpl_name, &tera_context)
+    let template_name = format!("shortcodes/{}.html", name);
+
+    let res =
+        utils::templates::render_template(&template_name, &context.tera, &tera_context, &None)
             .map_err(|e| Error::chain(format!("Failed to render {} shortcode", name), e))?;
 
     // Small hack to avoid having multiple blank lines because of Tera tags for example

components/site/tests/site.rs

@@ -629,3 +629,14 @@ fn can_apply_page_templates() {
     assert_eq!(child.meta.template, Some("page_template_child.html".into()));
     assert_eq!(child.meta.title, Some("Local section override".into()));
 }
+
+// https://github.com/getzola/zola/issues/571
+#[test]
+fn can_build_site_custom_builtins_from_theme() {
+    let (_, _tmp_dir, public) = build_site("test_site");
+
+    assert!(&public.exists());
+    // 404.html is a theme template.
+    assert!(file_exists!(public, "404.html"));
+    assert!(file_contains!(public, "404.html", "Oops"));
+}

components/templates/src/lib.rs

@@ -31,15 +31,24 @@ lazy_static! {
     pub static ref ZOLA_TERA: Tera = {
         let mut tera = Tera::default();
         tera.add_raw_templates(vec![
-            ("404.html", include_str!("builtins/404.html")),
-            ("rss.xml", include_str!("builtins/rss.xml")),
-            ("sitemap.xml", include_str!("builtins/sitemap.xml")),
-            ("robots.txt", include_str!("builtins/robots.txt")),
+            ("__zola_builtins/404.html", include_str!("builtins/404.html")),
+            ("__zola_builtins/rss.xml", include_str!("builtins/rss.xml")),
+            ("__zola_builtins/sitemap.xml", include_str!("builtins/sitemap.xml")),
+            ("__zola_builtins/robots.txt", include_str!("builtins/robots.txt")),
             ("anchor-link.html", include_str!("builtins/anchor-link.html")),
-            ("shortcodes/youtube.html", include_str!("builtins/shortcodes/youtube.html")),
-            ("shortcodes/vimeo.html", include_str!("builtins/shortcodes/vimeo.html")),
-            ("shortcodes/gist.html", include_str!("builtins/shortcodes/gist.html")),
-            ("shortcodes/streamable.html", include_str!("builtins/shortcodes/streamable.html")),
+            (
+                "__zola_builtins/shortcodes/youtube.html",
+                include_str!("builtins/shortcodes/youtube.html"),
+            ),
+            (
+                "__zola_builtins/shortcodes/vimeo.html",
+                include_str!("builtins/shortcodes/vimeo.html"),
+            ),
+            ("__zola_builtins/shortcodes/gist.html", include_str!("builtins/shortcodes/gist.html")),
+            (
+                "__zola_builtins/shortcodes/streamable.html",
+                include_str!("builtins/shortcodes/streamable.html"),
+            ),
             ("internal/alias.html", include_str!("builtins/internal/alias.html")),
         ])
         .unwrap();

components/utils/src/templates.rs

@@ -25,12 +25,23 @@ pub fn render_template(
     context: &Context,
     theme: &Option<String>,
 ) -> Result<String> {
+    // check if it is in the templates
     if tera.templates.contains_key(name) {
         return tera.render(name, context).map_err(|e| e.into());
     }
 
+    // check if it is part of a theme
     if let Some(ref t) = *theme {
-        return tera.render(&format!("{}/templates/{}", t, name), context).map_err(|e| e.into());
+        let theme_template_name = format!("{}/templates/{}", t, name);
+        if tera.templates.contains_key(&theme_template_name) {
+            return tera.render(&theme_template_name, context).map_err(|e| e.into());
+        }
+    }
+
+    // check if it is part of ZOLA_TERA defaults
+    let default_name = format!("__zola_builtins/{}", name);
+    if tera.templates.contains_key(&default_name) {
+        return tera.render(&default_name, context).map_err(|e| e.into());
     }
 
     // maybe it's a default one?

test_site/themes/sample/templates/404.html

@@ -0,0 +1 @@
+Oops