feature-file-validation

Testing & Quality

Validate Gherkin feature files for structural quality, determinism, and implementation independence, then verify each scenario has matching test automation. Use this skill whenever reviewing test files, feature files, or BDD scenarios — including during /code-review when .feature files or step definition files appear in the changeset. Also use when a user asks to "check my feature files", "validate my Gherkin", "are my scenarios testable", or "do my feature files have tests".

QUICK START

How to use this skill

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Prompt to paste

I want to install this Agent Skill for this project in Codex.

Source SKILL.md: https://github.com/bdfinst/agentic-dev-team/blob/HEAD/plugins/dev-team/skills/feature-file-validation/SKILL.md

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Feature File Validation

Feature files are the contract between intent and implementation. This skill validates two things: (1) are scenarios well-formed, deterministic, and behavioral? (2) does every scenario have matching test automation?

When to Run

During /code-review when .feature or step definition files are in the changeset
When test-review encounters feature files
When a user explicitly asks to validate feature files or BDD scenarios
Before /build as a pre-flight check

Step 1: Find Feature Files

Locate all .feature files in scope. If reviewing changed files only, limit to .feature files in the changeset plus any referenced by changed step definitions. If none found, report skip and stop.

Step 2: Validate Feature File Structure

For each feature file, check every category below. Read references/validation-rules.md for detailed patterns and examples.

Category	What to flag	Severity
Gherkin syntax	Missing Given/When/Then, bad Background, empty Examples, orphan steps, blank feature name	warning
Determinism	Time-dependent steps, order-dependent scenarios, environment-dependent steps, probabilistic assertions, uncontrolled concurrency	error
Implementation coupling	Technology names, code-level details, CSS selectors, performance constraints, data structure specifics in step text	warning
Scenario quality	Multiple When steps, vague assertions ("it works"), missing negative/edge cases	warning/suggestion

Step 3: Verify Test Automation Coverage

For each scenario, check whether test automation exists using two strategies. A match from either is sufficient. Read references/validation-rules.md for framework detection patterns and naming conventions.

Strategy A — Step definition matching: Find step definition files (per framework conventions) whose patterns match the scenario's step text. Covered when all steps have definitions.
Strategy B — Test file naming: Find test files named after the feature file (e.g., login.feature -> login.test.ts) that reference the scenario name.

Report per feature file: total scenarios, covered, uncovered, partially covered.

Step 4: Output

{
  "status": "pass|warn|fail",
  "issues": [
    {
      "severity": "error|warning|suggestion",
      "confidence": "high|medium|none",
      "file": "features/login.feature",
      "line": 12,
      "message": "Description of the issue",
      "category": "determinism|implementation-coupling|structure|coverage",
      "suggestedFix": "How to fix it"
    }
  ],
  "coverage": {
    "total_scenarios": 0,
    "covered": 0,
    "uncovered": 0,
    "partial": 0
  },
  "summary": "One-line summary"
}

Severity and confidence mappings are in references/validation-rules.md.