fixed tests

gulpfile.babel.js

@@ -93,9 +93,6 @@ gulp.task('test:cover', ['clean:cover', 'test:cover-hook'], () =>
 
 gulp.task('test:coveralls', () =>
   gulp.src('coverage/**/lcov.info')
-    .pipe(babel({
-      presets: ['env'],
-    }))
     .pipe(coveralls()),
 );
 

src/model/Step.js

@@ -95,13 +95,13 @@ export default class Step {
    * Create a workflow step. You should {@link Workflow#add add} it to a workflow or a compound step.
    *
    * @param {string} name - Step name. Must be unique in a parent step (e.g. {@link Workflow}).
-   * @param {Action=} action - Action to execute during the step. If no action is specified it will
+   * @param {Action=} [action={}] action - Action to execute during the step. If no action is specified it will
    * automatically be created based on the configuration. Multiple steps may share a single action.
    * @param {object} [config={}] - Action configuration containing input bindings.
    * It should include action description in case the action is missing.
    *
    */
-  constructor(name, action, config = {}) {
+  constructor(name, action = {}, config = {}) {
     if (_.isUndefined(name)) {
       throw new Error('Step must have a name');
     }