Example stub-content function for Drupal Migrate with YAML files

gistfile1.php

<?php

/**
 * Implements hook_drush_command().
 */
function example_drush_command() {
  $commands = array();

  $commands['stub-content'] = array(
    'callback' => 'drush_stub_content',
    'description' => 'Output YAML for a content type',
    'aliases' => array('ssc'),
    'examples' => array(
    ),
    'arguments' => array(
      'type' => 'The bundle name',
      'entity_type' => 'The entity type. Defaults to node',
      'count' => 'The number of items',
    ),
    'options' => array(
      'count' => array(
        'description' => 'Number of items to create',
        'default' => 1,
      ),
      'include-id' => array(
        'description' => 'Include an auto-generated ID in the id field',
      ),
      'include-title' => array(
        'description' => 'Include an auto-generated title in the title field',
      )
    ),
    'bootstrap' => DRUSH_BOOTSTRAP_DRUPAL_FULL,
  );

  return $commands;
}

/**
 * List fields in an entity/bundle
 *
 * @param string $type
 *   A string for the bundle.
 * @param string $entity_type
 *   The entity type for this bundle. Defaults to node.
 */
function drush_stub_content($type = NULL, $entity_type = 'node') {
  // if no types are passed, output types
  if (!$type) {
    return drush_typeinfo_list();
  }

  $type_info = entity_get_info($entity_type);
  if (!isset($type_info['bundles'][$type])) {
    drush_log(t('The requested type does not exist. Try: drush typeinfo-list'), 'error');
    return;
  }

  $label = $type_info['bundles'][$type]['label'];
  $field_info = field_info_instances($entity_type, $type);
  $fields = array(
    'id',
    'title'
  );

  foreach ($field_info as $field => $info) {
    array_push($fields, $field);
  }

  $output = '';
  foreach (range(1, drush_get_option('count', 1)) as $item) {
    $output .= "---\n";
    foreach ($fields as $field) {
      $value = '';
      if (drush_get_option('include-id') && $field === 'id') {
        $value = $item;
      }
      elseif (drush_get_option('include-title') && $field === 'title') {
        $value = ucfirst(str_replace('_', ' ', $type)) . ' ' . $item;
      }
      $output .= "  $field: $value\n";
    }
  }

  print $output;
}