Gherkin/cucumber implementation in dart.

For information on gherkin syntax and Behavior Driven Development (BDD) please see: http://cukes.info/


The fork of the project removed all Future-implementations and replaced them with the Dart2 async/await semantics. With this implementation the actual step implementations require a Completer as the first parameter that must be completed at the end of each test step. The reason is that the implementation uses the LibraryMirror.invoke method that cannot be used with await.


Dherkin can be executed in a number of ways.


Library comes with an executable runner script cucumberd in bin/ directory. Create symbolic link in a directory on your path, like /usr/local/bin:

cd /usr/local/bin
ln -s path/to/dherkin/bin/cucumberd .


cucumberd examples/test_feature.feature

Note: cucumberd will auto-include all step definitions in steps/ sub-directory. Ability to add steps source locations via command-line arguments is planned.

Custom Runner

Alternatively, you might opt for writing your own script:

   library my_bdd_runner;

   import 'package:dherkin/dherkin.dart';
   import 'my_step_defs.dart'; // import stepdefs, mandatory since no auto-scanning happens

   main(args) {

   // write your StepDefs below

Invoke the runner : $ dart my_bdd_runner.dart my_gherkin.feature

Anatomy of a stepdef

A stepdef is a top-level function annotated with one of Gherkin keywords. Such a function can take any number of positional parameters, and up to three optional named parameters.

@And("I am a table step \"(\\w+?)\"")
i_am_a_table(arg1, {exampleRow, table, out}) {

Table found on the step will be passed in as table. A scenario outline row will be passed in as exampleRow


Due to asynchronous nature of execution, output of print statements will not appear near the gherkin step that ran them. For that purpose, optional named parameter out will be injected if the stepdef function states that it takes it


Features and scenarios are executed in multiple workers, so there is a degree of unpredictability of the order of execution.