Table of Contents

jdgerkinator — Gherkin Generator

AI-powered tool that converts acceptance criteria into Gherkin .feature files, optionally integrating with existing Reqnroll / SpecFlow step definitions.

Quick start

# Install the tool
dotnet tool install -g JD.Tools.GherkinGenerator

# Pipe acceptance criteria from stdin
echo "Users can reset their password via email" | jdgerkinator

# Read criteria from a file
jdgerkinator --input requirements.txt --output ./features

# Scan an assembly for existing step definitions
jdgerkinator --assembly ./bin/Debug/net8.0/MyApp.Tests.dll \
             --features ./features \
             --input requirements.txt

CLI reference

Usage:  jdgerkinator [options]

Options:
  -a, --assembly <path>   .NET assembly DLL to scan for step definitions
  -f, --features <dir>    Directory of existing .feature files to integrate with
  -o, --output <dir>      Output directory for generated files
                          (default: ./generated-features)
  -m, --model <model>     Claude model (default: claude-sonnet-4-6)
  -i, --input <file>      File containing acceptance criteria
                          (reads from stdin if omitted)
  --version               Show version information
  -?, -h, --help          Show help and usage information

How it works

flowchart LR
    A[Acceptance Criteria] --> B[Claude Agent]
    C[Step Definitions] -.->|optional| B
    D[Existing Features] -.->|optional| B
    B --> E[.feature files]

1. Input collection

The tool reads acceptance criteria from --input or interactively from stdin. When --assembly is provided, the StepDefinitionScannerPlugin uses System.Reflection.MetadataLoadContext to inspect the assembly for [Given], [When], and [Then] attributes without loading it into the runtime.

2. Context gathering

If --features points to a directory of existing .feature files, the FeatureFilePlugin reads them so Claude can integrate new scenarios into existing features rather than creating duplicates.

3. Agentic generation

Claude receives:

  • The acceptance criteria text
  • Available step definitions (if scanned)
  • Existing feature files (if provided)

It then autonomously calls plugin functions to:

  1. Scan step definitions (scan_step_definitions)
  2. List and read existing features (list_feature_files, read_feature_file)
  3. Write new or appended .feature files (write_feature_file, append_to_feature_file)

4. Output

Generated .feature files are written to the output directory, following standard Gherkin syntax with proper Feature:, Scenario:, and step keywords.

Plugins

StepDefinitionScannerPlugin

Scans .NET assemblies for BDD step definitions using reflection-only loading.

Function Description
scan_step_definitions Loads an assembly via MetadataLoadContext and extracts [Given], [When], [Then] attributes with their regex patterns, method names, and declaring types

Supported attributes:

  • Reqnroll.GivenAttribute / WhenAttribute / ThenAttribute
  • TechTalk.SpecFlow.GivenAttribute / WhenAttribute / ThenAttribute

FeatureFilePlugin

Reads and lists existing .feature files for context.

Function Description
list_feature_files Recursively finds .feature files and extracts feature names and tags
read_feature_file Returns the full content of a specific feature file

GherkinWriterPlugin

Writes generated Gherkin to disk.

Function Description
write_feature_file Creates a new .feature file (creates directories as needed)
append_to_feature_file Appends scenarios to an existing .feature file
get_feature_template Returns a Gherkin template for reference

Architecture

GherkinGenerator/
├── Program.cs                              # CLI entry point (System.CommandLine)
├── Models/
│   ├── StepDefinition.cs                   # record(Keyword, Pattern, MethodName, DeclaringType)
│   └── FeatureFile.cs                      # record(Path, FeatureName, Content, Tags)
└── Plugins/
    ├── StepDefinitionScannerPlugin.cs      # Assembly scanning via MetadataLoadContext
    ├── FeatureFilePlugin.cs                # .feature file reader
    └── GherkinWriterPlugin.cs              # .feature file writer

Examples

Basic — criteria from stdin

jdgerkinator <<'EOF'
As a user I want to log in with my email and password
so that I can access my account.

Acceptance criteria:
- Valid credentials grant access
- Invalid password shows an error
- Account locked after 5 failed attempts
EOF

With assembly scanning

jdgerkinator \
  --assembly ./tests/MyApp.AcceptanceTests/bin/Debug/net8.0/MyApp.AcceptanceTests.dll \
  --features ./tests/MyApp.AcceptanceTests/Features \
  --output ./tests/MyApp.AcceptanceTests/Features \
  --input ./docs/sprint-42-criteria.txt

This scans the test assembly for step definitions, reads existing features, and generates new .feature files that reuse existing steps where possible.

Custom model

jdgerkinator --model claude-opus-4-6 --input complex-requirements.txt
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