Node.js Express.js: mock request object for unit-test purpose - unit-testing

Question

I have a method that check if request query string has some params:
checkMandatoryQueryParams (mandatoryQueryParams: String[], req: Request): void {
let result = true;
mandatoryQueryParams.forEach((element, idx) => {
if (!req.query.hasOwnProperty(element)) {
result = false;
}
});
return result;
}
in unit-testing i need to mock the request for test it, eg:
describe('Utils', () => {
it('checkMandatoryQueryParams', () => {
const req: Request = new Request(); // pseudo-code
req.query = "?foo=test&bar=test"; // pseudo-code
expect( checkMandatoryQueryParams(['foo', 'bar'], req) ).toEqual(true);
});
});
how can i mock the express request?

Answer 1

Two options:
Create your own mock object:
describe('Utils', () => {
/**
* Mocked Express Request object
*/
let mockedReq;
beforeEach(() => {
mockedReq = {
query: {}
};
})
it('checkMandatoryQueryParams', () => {
const req = mockedReq;
req.query = "?foo=test&bar=test"; // pseudo-code
expect(checkMandatoryQueryParams(['foo', 'bar'], req) ).toEqual(true);
});
});
Use manual mocks, similar to above:
describe('Utils', () => {
/**
* Mocked Express Request object
*/
let mockedReq;
beforeAll(() => {
mockedReq = jest.fn().mockImplementation(() => {
const req = {
// Implementation
};
return req;
});
});
beforeEach(() => mockedReq.mockReset())
it('checkMandatoryQueryParams', () => {
const req = mockedReq;
req.query = "?foo=test&bar=test"; // pseudo-code
expect(checkMandatoryQueryParams(['foo', 'bar'], req) ).toEqual(true);
});
});