lifecycle-test-example.js

   describe('Lifecycle', () => {
    let instance;
    let newComponent;
    const updateComponent = (props) => (
      <TestPage {...{ ...defaultProps, ...props }} />
    );

    beforeEach(() => {
      component = getComponent();
      instance = component.root.instance;
      instance.handleSetTableValues = jest.fn();
    });

    afterEach(() => {
      jest.clearAllMocks();
    });

    it('updates table values when `numCols` changes', () => {
      newComponent = updateComponent({ numCols: 0 });
      component.update(newComponent);
      expect(instance.handleSetTableValues).toHaveBeenCalled();
    });

    it('updates table values when `numRows` changes', () => {
      newComponent = updateComponent({ numRows: 0 });
      component.update(newComponent);
      expect(instance.handleSetTableValues).toHaveBeenCalled();
    });

    it('does not update table values when neither `numCols` or `numRows` changes', () => {
      newComponent = updateComponent();
      component.update(newComponent);
      expect(instance.handleSetTableValues).not.toHaveBeenCalled();
    });
  });