unit tests: add frontmatter unit tests

Cargo.toml

@@ -13,7 +13,8 @@ serde_json = "1.0"
 textwrap = "0.16"
 clap = { version = "4.4.4", features = ["derive"] }
 serde_yaml = "0.9.33"
-yaml-front-matter = "0.1.0"
+gray_matter = "0.2.6"
+relative-path = "1.9.2"
 
 [dev-dependencies]
 insta = "1.36.1"

src/frontmatter.rs

@@ -1,61 +1,109 @@
 use std::{
-    collections::HashMap,
     fs,
     path::{Path, PathBuf},
-    process::Command,
 };
 
+use gray_matter::engine::YAML;
+use gray_matter::Matter;
+use std::fmt;
+
+use relative_path::RelativePath;
 use serde::{Deserialize, Serialize};
-use yaml_front_matter::YamlFrontMatter;
 
-fn find_repo_root() -> Option<PathBuf> {
-    let output = Command::new("git")
-        .args(["rev-parse", "--show-toplevel"])
-        .output()
-        .ok()?
-        .stdout;
+#[derive(Deserialize, Serialize, Debug)]
+pub struct Frontmatter {
+    pub doc_location: Option<String>,
+}
 
-    let path_str = String::from_utf8(output).ok()?.trim().to_string();
-    Some(PathBuf::from(path_str))
+#[derive(Debug, PartialEq)]
+pub enum FrontmatterErrorKind {
+    InvalidYaml,
+    DocLocationFileNotFound,
+    DocLocationNotRelativePath,
 }
 
-#[derive(Deserialize, Serialize, Debug)]
-pub struct Matter {
-    #[serde(flatten)]
-    pub content: HashMap<String, serde_yaml::Value>,
+#[derive(Debug, PartialEq)]
+pub struct FrontmatterError {
+    pub message: String,
+    pub kind: FrontmatterErrorKind,
+}
+
+impl fmt::Display for FrontmatterError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        // Write the error message to the formatter
+        write!(f, "FrontmatterError: {}", self.message)
+    }
 }
 
-/// Returns the actual content of a markdown file, if the frontmatter has an import field.
-pub fn get_imported_content(file_path: &Path, markdown: Option<&String>) -> Option<String> {
-    markdown?;
-
-    match YamlFrontMatter::parse::<Matter>(markdown.unwrap()) {
-        Ok(document) => {
-            let metadata = document.metadata.content;
-
-            let abs_import = metadata.get("import").map(|field| {
-                let import_val = field
-                    .as_str()
-                    .expect("Frontmatter: import field must be a string");
-                match PathBuf::from(import_val).is_relative() {
-                    true => PathBuf::from_iter(vec![
-                        // Cannot fail because every file has a parent directory
-                        file_path.parent().unwrap().to_path_buf(),
-                        PathBuf::from(import_val),
-                    ]),
-                    false => PathBuf::from_iter(vec![
-                        find_repo_root()
-                        .expect("Could not find root directory of repository. Make sure you have git installed and are in a git repository"),
-                        PathBuf::from(format!(".{import_val}")),
-                    ]),
+/// Returns the actual content of a markdown file, if the frontmatter has a doc_location field.
+/// It returns None if the frontmatter is not present.
+/// It returns an error if the frontmatter is present but invalid. This includes:
+///     - Invalid yaml frontmatter
+///     - Invalid doc_location type
+///     - doc_location file is not readable or not found
+///     - doc_location field is not a relative path
+///     - doc_location file is not utf8
+pub fn get_imported_content(
+    file_path: &Path,
+    markdown: &str,
+) -> Result<Option<String>, FrontmatterError> {
+    let matter = Matter::<YAML>::new();
+
+    let result = matter.parse(markdown);
+
+    // If the frontmatter is not present, we return None
+    if result.data.is_none() {
+        return Ok(None);
+    }
+
+    let pod = result.data.unwrap();
+    match pod.deserialize::<Frontmatter>() {
+        Ok(metadata) => {
+            let abs_import = match metadata.doc_location {
+                Some(doc_location) => {
+                    let import_path: PathBuf = PathBuf::from(&doc_location);
+                    let relative_path = RelativePath::from_path(&import_path);
+
+                    match relative_path {
+                        Ok(rel) => Ok(Some(rel.to_path(file_path.parent().unwrap()))),
+                        Err(e) => Err(FrontmatterError {
+                            message: format!("{:?}: doc_location: field must be a path relative to the current file. Error: {} - {}", file_path, doc_location, e),
+                            kind: FrontmatterErrorKind::DocLocationNotRelativePath,
+                        }),
+                    }
                 }
-            });
+                // doc_location: field doesn't exist. Since it is optional, we return None
+                None => Ok(None),
+            };
+
+            match abs_import {
+                Ok(Some(path)) => match fs::read_to_string(&path) {
+                    Ok(content) => Ok(Some(content)),
+                    Err(e) => Err(FrontmatterError {
+                        message: format!(
+                            "{:?}: Failed to read doc_location file: {:?} {}",
+                            file_path, path, e
+                        ),
+                        kind: FrontmatterErrorKind::DocLocationFileNotFound,
+                    }),
+                },
+                Ok(None) => Ok(None),
+                Err(e) => Err(e),
+            }
+        }
 
-            abs_import.map(|path| {
-                fs::read_to_string(&path)
-                    .expect(format!("Could not read file: {:?}", &path).as_str())
+        Err(e) => {
+            let message = format!(
+                "{:?}: Failed to parse frontmatter metadata - {} YAML:{}:{}",
+                file_path,
+                e,
+                e.line(),
+                e.column()
+            );
+            Err(FrontmatterError {
+                message,
+                kind: FrontmatterErrorKind::InvalidYaml,
             })
         }
-        Err(_) => None,
     }
 }

src/main.rs

@@ -41,7 +41,7 @@ use rnix::{
     SyntaxKind, SyntaxNode,
 };
 use rowan::{ast::AstNode, WalkEvent};
-use std::{fs, path::Path};
+use std::{fs, path::Path, process::exit};
 
 use std::collections::HashMap;
 use std::io;
@@ -109,11 +109,26 @@ pub fn retrieve_doc_comment(
     let doc_comment = get_expr_docs(node);
 
     // Doc comments can import external file via "import" in frontmatter
-    let content = get_imported_content(file, doc_comment.as_ref()).or(doc_comment);
 
-    content.map(|inner| {
+    doc_comment.map(|inner| {
+        let content = handle_indentation(&inner).unwrap_or_default();
+
+        let final_content = match get_imported_content(file, &content) {
+            // Use the imported content instead of the original content
+            Ok(Some(imported_content)) => imported_content,
+
+            // Use the original content
+            Ok(None) => content,
+
+            // Abort if we failed to read the frontmatter
+            Err(e) => {
+                eprintln!("{}", e);
+                exit(1);
+            }
+        };
+
         shift_headings(
-            &handle_indentation(&inner).unwrap_or(String::new()),
+            &handle_indentation(&final_content).unwrap_or(String::new()),
             // H1 to H4 can be used in the doc-comment with the current rendering.
             // They will be shifted to H3, H6
             // H1 and H2 are currently used by the outer rendering. (category and function name)

src/snapshots/nixdoc__test__frontmatter_doc_location_e2e.snap

@@ -0,0 +1,18 @@
+---
+source: src/test.rs
+expression: output
+---
+# Debug {#sec-functions-library-debug}
+## Imported
+
+This is be the documentation
+
+## `lib.debug.item` {#function-library-lib.debug.item}
+
+### Imported
+
+This is be the documentation
+
+## `lib.debug.optional` {#function-library-lib.debug.optional}
+
+No frontmatter