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

1 files changed, 26 insertions, 0 deletions

diff --git a/subplot.md b/subplot.md
index 03e965e..b1c500b 100644
--- a/subplot.md
+++ b/subplot.md
@@ -2711,6 +2711,32 @@ This is another embedded file, and has the same name in uppercase.
 ```
 ~~~~
 
+
+### Fail if embedded file isn't used
+
+This scenario checks that we get warnings, when using a subplot with
+embedded files that aren't used.
+
+~~~scenario
+given file unusedfile.md
+and an installed subplot
+when I try to run subplot docgen unusedfile.md -o unusedfile.html
+then command is successful
+and file unusedfile.html exists
+and stderr contains "thisisnotused.txt"
+~~~
+
+~~~~{#unusedfile.md .file .markdown .numberLines}
+---
+title: Embedded file is not used by a scenario
+...
+
+```{#thisisnotused.txt .file}
+This is the embedded file.
+```
+~~~~
+
+
 ## Steps must match bindings
 
 Subplot permits the binding author to define arbitrarily complex regular