feat: warn about unused embedded files

This is merely a warning, for now, to stderr. subplot.md has two
embedded files used as examples, and I'm too tired to add a way to
indicate that it's OK for a specific file to not be used. That should
probably be added later, though.

Sponsored-by: author

2 files changed, 45 insertions, 2 deletions

diff --git a/src/bin/subplot.rs b/src/bin/subplot.rs
index 524535d..3353328 100644
--- a/src/bin/subplot.rs
+++ b/src/bin/subplot.rs
@@ -331,7 +331,9 @@ impl Docgen {
             .unwrap_or("");
         let template = template.to_string();
         event!(Level::TRACE, ?template);
-        if !doc.check_named_files_exist(&template)? || !doc.check_matched_steps_have_impl(&template)
+        if !doc.check_named_files_exist(&template)?
+            || !doc.check_matched_steps_have_impl(&template)
+            || !doc.check_embedded_files_are_used(&template)?
         {
             eprintln!("Continuing despite warnings");
         }
diff --git a/src/doc.rs b/src/doc.rs
index a32d6da..9989bc4 100644
--- a/src/doc.rs
+++ b/src/doc.rs
@@ -364,6 +364,44 @@ impl<'a> Document {
         Ok(okay)
     }
 
+    /// Check that all embedded files are used by matched steps.
+    #[instrument(level = "trace", skip(self))]
+    pub fn check_embedded_files_are_used(&mut self, template: &str) -> Result<bool> {
+        let mut filenames: HashSet<_> = self
+            .files()
+            .iter()
+            .map(|f| f.filename().to_lowercase())
+            .collect();
+        event!(Level::TRACE, ?filenames, "Checking that files are used");
+        let scenarios = match self.matched_scenarios(template) {
+            Ok(scenarios) => scenarios,
+            Err(_) => return Ok(true), // We can't do the check, so say it's okay.
+        };
+        for scenario in scenarios {
+            for step in scenario.steps() {
+                for captured in step.parts() {
+                    if let PartialStep::CapturedText { name, text } = captured {
+                        if matches!(step.types().get(name.as_str()), Some(CaptureType::File)) {
+                            filenames.remove(&text.to_lowercase());
+                        }
+                    }
+                }
+            }
+        }
+        for filename in filenames.iter() {
+            eprintln!(
+                "WARNING: embedded file is not used by any scenario: {}",
+                filename
+            );
+        }
+
+        // We always succeed. Subplot's own subplot had valid cases of
+        // an embedded file being used and we need to develop a way to
+        // mark such uses as OK, before we can make it an error to not
+        // use an embedded file in a scenario.
+        Ok(true)
+    }
+
     /// Check that all matched steps actually have function implementations
     #[instrument(level = "trace", skip(self))]
     pub fn check_matched_steps_have_impl(&mut self, template: &str) -> bool {
@@ -521,7 +559,10 @@ pub fn codegen(filename: &Path, output: &Path, template: Option<&str>) -> Result
         .unwrap_or_else(|| doc.template())?
         .to_string();
     event!(Level::TRACE, ?template);
-    if !doc.check_named_files_exist(&template)? || !doc.check_matched_steps_have_impl(&template) {
+    if !doc.check_named_files_exist(&template)?
+        || !doc.check_matched_steps_have_impl(&template)
+        || !doc.check_embedded_files_are_used(&template)?
+    {
         event!(Level::ERROR, "Found problems in document, cannot continue");
         eprintln!("Unable to continue");
         std::process::exit(1);