It is a Jest-ism that shouldn't be in our open source package.
People using Jest can implement a similar pattern directly.
all.length +
          ') ' +
          'for componentType:' +
          componentType,
      );
    }
    return all[0];
  },
  /**
   * Pass a mocked component module to this method to augment it with
   * useful methods that allow it to be used as a dummy React component.
   * Instead of rendering as usual, the component will become a simple
   * <div> containing any provided children.
   *
   * @param {object} module the mock function object exported from a
   *                        module that defines the component to be mocked
   * @param {?string} mockTagName optional dummy root tag name to return
   *                              from render method (overrides
   *                              module.mockTagName if provided)
   * @return {object} the ReactTestUtils object (for chaining)
   */
  mockComponent: function(module, mockTagName) {
    mockTagName = mockTagName || module.mockTagName || 'div';
    module.prototype.render.mockImplementation(function() {
      return React.createElement(mockTagName, null, this.props.children);
    });
    return this;
  },
  nativeTouchData: function(x, y) {
    return {