subplot.md: Add a missing scenario in test input

Signed-off-by: Daniel Silverstone <dsilvers@digital-scurf.org>

1 files changed, 31 insertions, 0 deletions

diff --git a/subplot.md b/subplot.md
index a718490..2d7d760 100644
--- a/subplot.md
+++ b/subplot.md
@@ -1071,6 +1071,30 @@ and step "then bar was done" was run
 and command is successful
 ~~~
 
+## No scenarios means codegen fails
+
+If you attempt to `subplot codegen` on a document which contains no scenarios, the
+tool will fail to execute with a reasonable error message.
+
+~~~scenario
+given file noscenarios.md
+and an installed subplot
+when I try to run subplot codegen noscenarios.md -o test.py
+then command fails
+and stderr contains "no scenarios were found"
+~~~
+
+~~~{#noscenarios.md .file .markdown .numberLines}
+---
+title: No scenarios in here
+template: python
+...
+
+# This is a title
+
+But there are no scenarios in this file, and thus nothing can be generated in a test suite.
+
+~~~
 
 ## Keywords
 
@@ -2099,6 +2123,13 @@ template: python
 
 This is a very simple Markdown file that uses every kind of inline
 markup in the title and chapter heading.
+
+To satisfy codegen, we *MUST* have a scenario here
+~~~~scenario
+when I do bar
+then bar was done
+~~~~
+
 ~~~