Typed Data Tables

The default LIST_OF_OBJECT_PARAMS data-table mode — Gherkin data tables generate type-safe inner classes with typed accessors. No Cucumber dependency.

Source: examples/common-use-cases/example-1 on GitHub.

What this demonstrates

• Data tables generate inner Param classes (named after the last word of the step text + Param)
• Column headers become typed fields with automatic type inference
• Per-column inference: Integer, Double, Boolean, String, …
• Readable headers (e.g. unit price) are sanitised to Java field names (unitPrice)
• Each row becomes a new XxxParam(...) call inside List.of(...)
• Multiple data tables in the same feature produce separate inner classes
• The concrete test reads rows through the typed accessors — no string parsing

The Gherkin

Given my cart contains the following products:
  | name                | qty | unit price | in stock |
  | Wireless Headphones | 1   | 59.99      | true     |
  | Coffee Beans 1kg    | 3   | 12.50      | true     |
  | USB-C Cable         | 2   | 8.99       | false    |

The spec, ShoppingCart.specb, sits next to its marker class in src/test/java, so the marker needs only a bare @Gherkin2JUnit — the processor finds the spec by convention.

The generated inner class

public static class ProductsParam {
    private final String name;
    private final Integer qty;
    private final Double unitPrice;
    private final Boolean inStock;

    public ProductsParam(String name, Integer qty, Double unitPrice, Boolean inStock) {
        this.name = name;
        this.qty = qty;
        this.unitPrice = unitPrice;
        this.inStock = inStock;
    }

    public String  name()      { return this.name; }
    public Integer qty()       { return this.qty; }
    public Double  unitPrice() { return this.unitPrice; }
    public Boolean inStock()   { return this.inStock; }
}

The generated step method and call site

// Step method signature
public abstract void myCartContainsTheFollowingProducts(List<ProductsParam> products);

// Generated call site
myCartContainsTheFollowingProducts(
        List.of(
                new ProductsParam("Wireless Headphones", 1, 59.99, true),
                new ProductsParam("Coffee Beans 1kg",    3, 12.50, true),
                new ProductsParam("USB-C Cable",         2,  8.99, false)
        ));

Implementing the steps

The concrete ShoppingCartTest extends the generated ShoppingCartScenarios and works with the rows as typed objects — product.qty() is an Integer, product.inStock() a Boolean:

public class ShoppingCartTest extends ShoppingCartScenarios {

    private List<ProductsParam> products;
    private double subtotal;

    @Override
    public void myCartContainsTheFollowingProducts(List<ProductsParam> products) {
        this.products = products;
    }

    @Override
    public void iCalculateTheSubtotal() {
        subtotal = products.stream()
                .mapToDouble(product -> product.qty() * product.unitPrice())
                .sum();
    }

    @Override
    public void theCartSubtotalShouldBe$p1(Double expectedSubtotal) {
        assertEquals(expectedSubtotal, subtotal, 0.001);
    }

    // … the stock-check and bulk-discount steps work the same way
}

ShoppingCartFeature.java          (marker class, bare @Gherkin2JUnit)
  └→ ShoppingCartScenarios.java   (generated, abstract — the Param classes and @Test methods)
      └→ ShoppingCartTest.java    (your concrete class, implements the steps)

Key points

• Each unique data table shape in a feature produces its own Param class
• Field accessors use record-style names (name(), not getName())
• No Cucumber dependency — these are plain Java classes
• For compile-time enum safety on a column, see Type Refinement with Enums

Run it

cd examples/common-use-cases/example-1
mvn test