Make front matter test more lenient

During the migration to Zola, it was nice to have the enforcement that
all front matter is formatted identically. But going into the future,
the purpose of this test will be to help blog authors spot mistakes in
their front matter. It would be annoying noise a fail because the keys
are in a different order, whitespace, comments etc.

Author: senekor

front_matter/src/lib.rs

@@ -3,7 +3,7 @@ use serde::{Deserialize, Serialize};
 use toml::value::Date;
 
 /// The front matter of a markdown blog post.
-#[derive(Debug, PartialEq, Serialize, Deserialize)]
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
 pub struct FrontMatter {
     /// Deprecated. The plan was probably to have more specialized templates
     /// at some point. That didn't materialize, all posts are rendered with the
@@ -42,7 +42,7 @@ pub struct FrontMatter {
     pub extra: Extra,
 }
 
-#[derive(Debug, Default, PartialEq, Serialize, Deserialize)]
+#[derive(Debug, Clone, Default, PartialEq, Serialize, Deserialize)]
 pub struct Extra {
     pub team: Option<String>,
     pub team_url: Option<String>,
@@ -73,8 +73,12 @@ pub fn parse(markdown: &str) -> eyre::Result<(FrontMatter, &str)> {
 }
 
 /// Normalizes the front matter of a markdown file.
-pub fn normalize(markdown: &str, slug: &str, inside_rust: bool) -> eyre::Result<String> {
-    let (mut front_matter, content) = parse(markdown)?;
+pub fn normalize(
+    front_matter: &FrontMatter,
+    slug: &str,
+    inside_rust: bool,
+) -> eyre::Result<FrontMatter> {
+    let mut front_matter = front_matter.clone();
 
     // migrate "author" to "authors" key
     if let Some(author) = front_matter.author.take() {
@@ -110,14 +114,10 @@ pub fn normalize(markdown: &str, slug: &str, inside_rust: bool) -> eyre::Result<
         bail!("extra.team and extra.team_url must always come in a pair");
     }
 
-    Ok(format!(
-        "\
-+++
-{}\
-+++
-{content}",
-        toml::to_string_pretty(&front_matter)?
-    ))
+    let serialized = toml::to_string_pretty(&front_matter)?;
+    let deserialized = toml::from_str(&serialized)?;
+
+    Ok(deserialized)
 }
 
 #[cfg(test)]
@@ -146,11 +146,21 @@ mod tests {
                 .contains("content/inside-rust/");
 
             let content = fs::read_to_string(&post).unwrap();
-            let normalized = normalize(&content, slug, inside_rust).unwrap_or_else(|err| {
+            let (front_matter, rest) = parse(&content).unwrap();
+            let normalized = normalize(&front_matter, slug, inside_rust).unwrap_or_else(|err| {
                 panic!("failed to normalize {:?}: {err}", post.file_name().unwrap());
             });
 
-            if content != normalized {
+            if front_matter != normalized {
+                let normalized = format!(
+                    "\
+                    +++\n\
+                    {}\
+                    +++\n\
+                    {rest}\
+                    ",
+                    toml::to_string_pretty(&normalized).unwrap(),
+                );
                 if env::var("FIX_FRONT_MATTER").is_ok() {
                     fs::write(post, normalized).unwrap();
                     continue;