Cucumber JVM Documentation

By default, Cucumber interprets empty cells in Gherkin data tables as null.

To represent empty strings, you can configure a replacement string (e.g., [blank]) using the replaceWithEmptyString argument in DataTableType, DefaultDataTableCellTransformer, or DefaultDataTableEntryTransformer.

package com.example.app;

import io.cucumber.datatable.DataTable;
import io.cucumber.java8.En;

import java.util.List;
import java.util.Map;

import static org.junit.jupiter.api.Assertions.assertEquals;

class StepDefinitions implements En {
    
    StepDefinitions() {
        // Configure '[blank]' to be treated as an empty string replacement
        DataTableType("[blank]", (Map<String, String> entry) -> new Author(
            entry.get("name"),
            entry.get("first publication")
        ));
    
        Given("some authors",  (DataTable authorsTable) -> {
          // authors = [Author(name="Aspiring Author", firstPublication=null), Author(name="Ancient Author", firstPublication="")]
        });
    }
}

To ensure all Cucumber dependencies are synchronized to the same version within a Maven project, use the cucumber-bom. By importing the BOM in your <dependencyManagement> section, you can declare Cucumber dependencies (like cucumber-java or cucumber-junit) without specifying their versions explicitly.

<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>io.cucumber</groupId>
            <artifactId>cucumber-bom</artifactId>
            <version>${cucumber.version}</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
    </dependencies>
</dependencyManagement>

<!-- Then for example -->

<dependencies>
    <dependency>
        <groupId>io.cucumber</groupId>
        <artifactId>cucumber-java</artifactId>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>io.cucumber</groupId>
        <artifactId>cucumber-junit</artifactId>
        <scope>test</scope>
    </dependency>
</dependencies>

To avoid writing manual transformers for every type, you can implement TableEntryByTypeTransformer and TableCellByTypeTransformer. This allows you to use an object mapper like Jackson to automatically convert cells and entries to any registered type.

Note: If both are installed, Cucumber defaults to assuming table entries over table cells. You can resolve this ambiguity by ensuring your tables include a header row.

private class JacksonDataTableTransformer implements TableEntryByTypeTransformer, TableCellByTypeTransformer {

    ObjectMapper objectMapper = new tools.jackson.databind.ObjectMapper();
    
    @Override
    public <T> T transform(String value, Class<T> cellType) {
        return objectMapper.convertValue(value, cellType);
    }

    @Override
    public <T> T transform(Map<String, String> entry, Class<T> type, TableCellByTypeTransformer cellTransformer) {
        return objectMapper.convertValue(entry, type);
    }
}