I am using the html-pdf package in my nodejs code (not in Typescript). Now, this package has a create() function which is chained with the toBuffer() function. I am unit testing my code using Jest and want to mock this call pdf.create(html).toBuffer().
var pdf = require('html-pdf');
pdf.create(html).toBuffer(function(htmlToPdfError, buffer){
if (htmlToPdfError) {
reject(htmlToPdfError);
}
resolve(buffer.toString('base64'));
});
EDIT: I am trying to use the following code in my spec file to make the module:
jest.mock('html-pdf', () => ({
create: jest.fn(() => {
return Promise.resolve();
})
}));
This is helping me mock the create() function but I do not know how to return a object in Promise.resolve which would have a toBuffer function
will this work?
and then assert that your "pdf" buffer contains "test string"?
jest.mock('html-pdf', () => ({
create: jest.fn(() => {
return Promise.resolve({
toBuffer: function(callback) {
callback(null, Buffer.from("test string", "utf-8"));
},
});
})
}));
(I haven't tried it)
I could mock it using the following code:
const mockToBuffer = {
toBuffer: jest.fn((callback: Function) => callback(null, null)),
}
jest.mock('html-pdf', () => ({
create: jest.fn(() => mockToBuffer),
}))
it('Should work', async () => {
const expectedResult = Buffer.from([10])
mockToBuffer.toBuffer.mockImplementation((callback: Function) => {
callback(null, expectedResult)
})
// const result = await yourFuncUsingHtmlPdf(/* fakePayload */)
// Comparing the buffer using the native function
// expect(expectedResult.equals(result)).toBe(true)
}