function resetFieldMock() {
  fieldMock = new FieldMock();
  /**
   * @suppress {visibility,checkTypes} suppression added to enable type
   * checking
   */
  bubblePlugin.fieldObject = fieldMock;
}
Similar in intent to mock reset, but implemented by recreating the mock
variable. $reset() can't work because it will reset general any-time
expectations done in the fieldMock constructor.