如何使用 Jest 测试导入/导出？

Question

这是我的结构：

如您所见，我对文件 shipments.js 有 100% 的测试覆盖率，这些测试如下：

import shipmentsPagination, {
  setFilters,
  removeFilter,
  toggleFiltersModal,
  setCSVDataAction,
} from '../../actions/shipments';

describe('shipments redux actions', () => {
  it('should test setCSVDataAction', () => {
    const result = setCSVDataAction({
      itemsCount: 0,
      shipments: [],
    });

    expect(result.type).toEqual('SET_CSV_DATA');
    expect(result.payload).toEqual({
      shipmentsCSV: {
        itemsCount: 0,
        shipments: [],
      },
    });
  });

  it('should test toggleFiltersModal', () => {
    const result = toggleFiltersModal(true);

    expect(result.type).toEqual('TOGGLE_SHIPMENTS_FILTERS_MODAL');
  });

  it('should test removeFilter', () => {
    const filters = {
      shipmentId: '123',
      status: 'received',
      carrier: 'FedEx',
      shippedFrom: 'Dallas',
      shippedTo: 'NY',
      shippedDate: '10/13/2018',
      shipmentType: 'Colocation Hardware',
    };

    const result = removeFilter(filters);

    expect(result.type).toEqual('REMOVE_SHIPMENTS_FILTER');
    expect(result.payload).toEqual({ [filters]: '' });
  });

  it('should test shipmentsPagination', () => {
    const result = shipmentsPagination({
      page: 2,
      pageSize: 25,
    });

    expect(result.type).toEqual('UPDATE_SHIPMENTS_PAGINATION');
    expect(result.payload).toEqual({ page: 2, pageSize: 25 });
  });

  it('should test setFilters', () => {
    const result = setFilters({
      shipmentId: '123',
      status: 'Received',
      carrier: 'FedEx',
      shippedFrom: 'Houston - HOU02',
      shippedTo: 'Herp',
      shippedDate: '1/24/2019',
      shipmentType: 'Colocation Hardware',
    });

    expect(result.type).toEqual('SET_SHIPMENTS_FILTERS');
    expect(result.payload).toEqual({
      shipmentId: '123',
      status: 'Received',
      carrier: 'FedEx',
      shippedFrom: 'Houston - HOU02',
      shippedTo: 'Herp',
      shippedDate: '1/24/2019',
      shipmentType: 'Colocation Hardware',
    });
  });
});

如您所见，index.js 在第 1 行没有覆盖范围。

index.js是这个：

import shipments from './shipments';

export default {
  shipments,
};

那么我如何测试导入/导出以获得 100% 的测试覆盖率？

Answer 1

从我所看到的代码中，只需在测试中从index.js 导入shipmentsPagination：

import defaultExport from '../../actions/';  // import the default export from index.js
const { shipments: shipmentsPagination } = defaultExport; // and use it to get shipmentsPagination
import {
  setFilters,
  removeFilter,
  toggleFiltersModal,
  setCSVDataAction,
} from '../../actions/shipments'; // everything else can come from shipments.js

从index.js 导入shipmentsPagination 将确保index.js 中的export 行得到测试。

Answer 2

@mystackrunnethover 是对的，并不完全需要覆盖该行，但是，以防万一：

我将这些测试用作“健全性测试”，以确保 Jest 正常运行。

一个常见的陷阱是假设如果导入失败，imported_thing.toBeTruth() 将失败。它不会 - imported_thing 将是一个空对象，这是真的。

这是我们使用的：

import Account from '/account';

//describe block

expect(Account).toBeTruthy();

expect(Object.keys(Account).length > 0).toBe(true);

当然，这仅适用于Account 实际具有属性（并且应该具有）的情况。另一种方法是专门检查您期望的属性。