Report a step placed before the first scenario or background (#779)

[golikovichev]

Fixes #779.

Problem

gherkin-official 31 and later no longer raise a parse error when a step keyword (Given/When/Then/And/But) is placed before the first scenario or background. Instead the line is folded into the feature description. pytest-bdd relied on gherkin raising that error (mapped through ERROR_PATTERNS) to produce FeatureError: Step definition outside of a Scenario or a Background., so on newer gherkin the malformed feature was accepted silently and tests/parser/test_errors.py::test_step_outside_scenario_or_background_error started failing.

Fix

After a successful parse, pytest-bdd now checks whether the first non-empty line of the feature description starts with a step keyword and raises the same FeatureError if so. This keeps the behaviour consistent across all supported gherkin-official versions: older versions still report it through the existing parse-error path, newer versions through this post-parse check.

The check only looks at the first non-empty description line, so a legitimate multi-line description that mentions a keyword later is not affected (covered by tests/feature/test_steps.py::test_keywords_used_outside_steps). Like the existing ERROR_PATTERNS, it matches the English step keywords.

Testing

• test_step_outside_scenario_or_background_error passes again.
• test_keywords_used_outside_steps still passes (no false positive).
• Verified locally on gherkin-official 30.1.3 and 40.0.0.

[youtux]

I think we should rather have the Gherkin lead here and follow the same logic

[golikovichev]

Good call. Switched to the Gherkin dialect keywords for the feature's language instead of the hardcoded English ones, so the check follows Gherkin's own step detection and works for non-English features too. Added a French regression test.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.19%. Comparing base (582f045) to head (b93a7cc).

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #813      +/-   ##
==========================================
+ Coverage   96.12%   96.19%   +0.07%     
==========================================
  Files          55       55              
  Lines        2423     2471      +48     
  Branches      136      142       +6     
==========================================
+ Hits         2329     2377      +48     
  Misses         57       57              
  Partials       37       37              

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[golikovichev]

Merged main to resolve the conflict, and added tests covering the remaining branches of the description check: an unknown language yields no keywords, a keyword later in a description is allowed, a missing feature is a no-op, and the location fallback fires when the offending line is not found verbatim. CI should be green now. The switch to the Gherkin dialect keywords is still in place, so the detection follows Gherkin's own step logic. Happy to adjust anything.