我正在使用一个库“ pdfmake”,并且我想使用jest编写测试用例。我有一个模块pdf。在模块pdf内部,我正在导出2个函数。在这两个出口中,我都使用“ pdfmake”的内部函数来生成pdf。
以下是代码段:pdf.js
const PdfPrinter = require("pdfmake");
const fonts = require("./../shared/fonts");
const printer = new PdfPrinter(fonts);
const intiateDocCreation = docDefinition =>
printer.createPdfKitDocument(docDefinition);
const finishDocCreation = (pdfDoc, pdfStream) => {
pdfDoc.pipe(pdfStream);
pdfDoc.end();
};
module.exports = {
intiateDocCreation,
finishDocCreation
};
我尝试使用
const PdfPrinter = require("pdfmake");
jest.mock("pdfmake", () => {
return {
createPdfKitDocument: jest.fn().mockImplementation(() => ({ a: "b" }))
};
});
describe("test", () => {
test("pdf", () => {
const printer = new PdfPrinter(fonts);
printer.createPdfKitDocument();
expect(printer.createPdfKitDocument).toHaveBeenCalledTimes(1);
});
});
开玩笑给出一个错误:
TypeError:PdfPrinter不是构造函数
[您快到了,如果要模拟节点模块(pdfmake
)的构造函数,则需要在jest.fn()
的工厂函数内返回jest.mock
。
例如pdf.js
:
const PdfPrinter = require('pdfmake');
// const fonts = require('./../shared/fonts')
const fonts = {};
const printer = new PdfPrinter(fonts);
const intiateDocCreation = (docDefinition) => printer.createPdfKitDocument(docDefinition);
const finishDocCreation = (pdfDoc, pdfStream) => {
pdfDoc.pipe(pdfStream);
pdfDoc.end();
};
module.exports = {
intiateDocCreation,
finishDocCreation,
};
pdf.test.js
:
const PdfPrinter = require('pdfmake');
jest.mock('pdfmake', () => {
const mPdfMake = {
createPdfKitDocument: jest.fn().mockImplementation(() => ({ a: 'b' })),
};
return jest.fn(() => mPdfMake);
});
describe('test', () => {
test('pdf', () => {
const fonts = {};
const printer = new PdfPrinter(fonts);
printer.createPdfKitDocument();
expect(printer.createPdfKitDocument).toHaveBeenCalledTimes(1);
});
});
单元测试结果:
PASS src/stackoverflow/59250480/pdf.test.js (12.04s)
test
✓ pdf (6ms)
Test Suites: 1 passed, 1 total
Tests: 1 passed, 1 total
Snapshots: 0 total
Time: 13.694s