class FieldExampleBrowserTestBase

abstract class FieldExampleBrowserTestBase extends ExamplesBrowserTestBase {
    
    /**
     * {@inheritdoc}
     */
    protected $defaultTheme = 'classy';
    
    /**
     * The content type name.
     *
     * @var string
     */
    protected $contentTypeName;
    
    /**
     * The administrator account.
     *
     * @var \Drupal\Core\Session\AccountInterface
     */
    protected $administratorAccount;
    
    /**
     * The author account.
     *
     * @var \Drupal\Core\Session\AccountInterface
     */
    protected $authorAccount;
    
    /**
     * The field name.
     *
     * @var string
     */
    protected $fieldName;
    
    /**
     * Modules to enable.
     *
     * @var array
     */
    public static $modules = [
        'block',
        'node',
        'field_ui',
        'field_example',
    ];
    
    /**
     * {@inheritdoc}
     *
     * Once installed, a content type with the desired field is created.
     */
    protected function setUp() {
        // Install Drupal.
        parent::setUp();
        // Create and login a user that creates the content type.
        $permissions = [
            'administer content types',
            'administer node fields',
            'administer node form display',
            'administer node display',
        ];
        $this->administratorAccount = $this->drupalCreateUser($permissions);
        parent::drupalLogin($this->administratorAccount);
        // Prepare a new content type where the field will be added.
        $this->contentTypeName = strtolower($this->randomMachineName(10));
        $this->drupalGet('admin/structure/types/add');
        $edit = [
            'name' => $this->contentTypeName,
            'type' => $this->contentTypeName,
        ];
        $this->drupalPostForm(NULL, $edit, 'Save and manage fields');
        $this->assertText((string) new FormattableMarkup('The content type @name has been added.', [
            '@name' => $this->contentTypeName,
        ]));
        // Reset the permission cache.
        $create_permission = 'create ' . $this->contentTypeName . ' content';
        $this->checkPermissions([
            $create_permission,
        ]);
        // Now that we have a new content type, create a user that has privileges
        // on the content type.
        $this->authorAccount = $this->drupalCreateUser([
            $create_permission,
        ]);
    }
    
    /**
     * Create a field on the content type created during setUp().
     *
     * @param string $type
     *   The storage field type to create.
     * @param string $widget_type
     *   The widget to use when editing this field.
     * @param int|string $cardinality
     *   Cardinality of the field. Use -1 to signify 'unlimited'.
     * @param string $fieldFormatter
     *   The formatter to use when editing this field.
     *
     * @return string
     *   Name of the field, like field_something
     */
    protected function createField($type = 'field_example_rgb', $widget_type = 'field_example_text', $cardinality = '1', $fieldFormatter = 'field_example_simple_text') {
        $assert = $this->assertSession();
        $this->drupalGet('admin/structure/types/manage/' . $this->contentTypeName . '/fields');
        // Go to the 'Add field' page.
        $this->clickLink('Add field');
        // Make a name for this field.
        $field_name = strtolower($this->randomMachineName(10));
        // Fill out the field form.
        $edit = [
            'new_storage_type' => $type,
            'field_name' => $field_name,
            'label' => $field_name,
        ];
        $this->drupalPostForm(NULL, $edit, 'Save and continue');
        // Fill out the $cardinality form as if we're not using an unlimited number
        // of values.
        $edit = [
            'cardinality' => 'number',
            'cardinality_number' => (string) $cardinality,
        ];
        // If we have -1 for $cardinality, we should change the form's drop-down
        // from 'Number' to 'Unlimited'.
        if (-1 == $cardinality) {
            $edit = [
                'cardinality' => '-1',
                'cardinality_number' => '1',
            ];
        }
        // And now we save the cardinality settings.
        $this->drupalPostForm(NULL, $edit, 'Save field settings');
        $this->verbose((string) new FormattableMarkup('Saved settings for field %field_name with widget %widget_type and cardinality %cardinality', [
            '%field_name' => $field_name,
            '%widget_type' => $widget_type,
            '%cardinality' => $cardinality,
        ]));
        $assert->pageTextContains((string) new FormattableMarkup('Updated field @name field settings.', [
            '@name' => $field_name,
        ]));
        // Set the widget type for the newly created field.
        $this->drupalGet('admin/structure/types/manage/' . $this->contentTypeName . '/form-display');
        $edit = [
            'fields[field_' . $field_name . '][type]' => $widget_type,
        ];
        $this->drupalPostForm(NULL, $edit, 'Save');
        // Set the field formatter for the newly created field.
        $this->drupalGet('admin/structure/types/manage/' . $this->contentTypeName . '/display');
        $edit1 = [
            'fields[field_' . $field_name . '][type]' => $fieldFormatter,
        ];
        $this->drupalPostForm(NULL, $edit1, 'Save');
        return $field_name;
    }

}