feat! don't allow indented scenario steps

Some day we will have syntax for continuing a step to the next line.
This change makes it easier to introduce that syntax, without a
breaking change.

Sponsored-by: author

1 files changed, 36 insertions, 0 deletions

diff --git a/subplot.md b/subplot.md
index bb4bd75..cae70f6 100644
--- a/subplot.md
+++ b/subplot.md
@@ -1059,6 +1059,42 @@ and step "then bar was done" was run
 and command is successful
 ~~~
 
+## Indented scenario steps are not allowed
+
+_Requirement: A scenario step starts at the beginning of the line._
+
+Justification: We may want to allow continuing a step to the next
+line, but as of June, 2023, we haven't settled on a syntax for this.
+However, whatever syntax we do eventually choose, it will be easier
+to add that if scenario steps start at the beginning of a line,
+without making a breaking change.
+
+~~~scenario
+given file indented-step.subplot
+given file indented-step.md
+given file b.yaml
+given an installed subplot
+when I try to run subplot docgen indented-step.subplot -o foo.html
+then command fails
+and stderr contains "indented"
+~~~
+
+~~~{#indented-step.subplot .file .yaml .numberLines}
+title: Indented scenario step
+markdowns:
+  - indented-step.md
+bindings:
+  - b.yaml
+~~~
+
+~~~~~~{#indented-step.md .file .markdown .numberLines}
+# This is a title
+
+~~~scenario
+  given precondition
+~~~
+~~~~~~
+
 ## No scenarios means codegen fails
 
 If you attempt to `subplot codegen` on a document which contains no scenarios, the