I am working on a tdd project with Node.js and Typescript. I have a class named HttpSample which is imported to another class named Sample as follows.
import {HttpSample} from "./httpService"
...
const http: HttpSample = new HttpSample();
http.get();
How can I mock the HttpSample class inside the Sample's test file?
Update
I am using Jasmine and mocha frameworks
ts-mock-imports is a library that is designed to fix this issue in Typescript while remaining type safe. It's built on top of sinon instead of Jasmine but will play nice with both.
In sample.spec.ts
import * as httpSample from './httpService';
import { ImportMock } from 'ts-mock-imports';
import { Sample } from './sample';
const httpMock = ImportMock.mockClass(httpSample, 'HttpSample');
// Sample will now get a mock version of HttpSample
const sample = new Sample();
Related
I have an external library that is exported as a function, in the Stub documentation it only accepts an input with the first parameter as object and the second parameter as method , so how could I stub a library that is exported as a function in a Node ES Modules environment (without Commonjs)?
(In my specific case, I had used a library that use the internet to work, and I wanted to test derivated functions without accessing the internet, so I want to stub the external function library)
Attempts:
I couldn't use solutions like proxyquire as it is a solution based on require and module cache deletion, which are not supported within Node's ES modules.
I don't want to use proxyquire-universal because it simulates the operation of require in normal ES, and it's just a function in the whole project that I wanted to test, I was looking for a simpler solution
Changing the import mode doesn't work as it's not recompiled like in babel, so even if I import as import * as obj from 'lib' only the function name is changed
I had this error environment with 3 files:
An external library called "sum" for example, which I don't want to change, exported as follows:
External Library: externalSum.js
module.exports = function sum(a, b){
console.log(">>>>> running without stub <<<<<")
return a + b
}
This library used in the middle of a project file called mathProblems
Internal File: mathProblems.js
import sum from 'externalSum'
export function sumMore1(a) {
return sum(a, 1);
}
And I have a test file
Internal File: spec.js
import sinon from 'sinon'
import assert from 'assert'
import sumObj from 'externalSum'
import { sumMore1 } from '../mathProblems.js'
describe('sumMore1 is working', () => {
it('sumMore1 test', () => {
const sum_stub = sinon.stub(sumObj) // NOT STUBBING
sum_stub.withArgs(1, 1).returns(2) // NOT STUBBING
const result = sumMore1(1)
assert.strictEqual(result, 2)
});
});
I didn't find this solution anywhere on the internet, i found some solutions that work for node with request or babilon, but not for my case using ES Modules:
https://github.com/sinonjs/sinon/issues/562
https://minaluke.medium.com/how-to-stub-spy-a-default-exported-function-a2dc1b580a6b
So I wanted to register the solution in case anyone needs it.
To solve this, create a new file, which can be allocated anywhere in the project, in this case I will call it sumImport.js:
Internal File: sumImport.js
import sum from 'externalSum';
// export as object
export default {
sum
}
The object needs to be called inside the created function I want to test, and changed the import way:
Internal File: mathProblems.js
import sumObj from './sumImport.js';
export function sumMore1(a) {
const { sum } = sumObj;
return sum(a, 1);
}
And I finally managed to import as an object in the test:
Internal File: spec.js
import sinon from 'sinon'
import assert from 'assert'
import sumObj from '../sumImport.js'
import { sumMore1 } from '../mathProblems.js'
describe('sumMore1 is working', () => {
it('sumMore1 test', () => {
const sum_stub = sinon.stub(sumObj, "sum") // STUBBED
sum_stub.withArgs(1, 1).returns(2) // STUBBED
const result = sumMore1(1)
assert.strictEqual(result, 2)
});
});
I hope it helps someone and if someone else has some better solutions I would also be grateful!
I'm trying to understand why require works while import does not for an npm package. The package is r7insight_node and allows us to send our logs to their product, Rapid7. When we use require as per their instructions things work fine, but don't when I use import.
Their library has an src/index.js file that looks like:
// Use codependency for dynamically loading winston
const requirePeer = codependency.register(module);
// Import winston
const winston = requirePeer('winston', {optional: true});
const Transport = requirePeer('winston-transport', {optional: true});
// If we have successfully loaded winston (user has it)
// we initialize our InsightTransport
if (winston) {
provisionWinston(winston, Transport);
}
// Logger is default export
module.exports = Logger;
// Export as `bunyanStream` to not break existing integration
module.exports.bunyanStream = buildBunyanStream;
module.exports.provisionWinston = provisionWinston;
My understanding is that require is synchronous and is "computed" whereas import is asynchronous and is NOT "computed" as written here. Is this the reason for why require works while import does not?
Does "computed" mean in that the index.js file is executed and hence the if (winston) block is checked and executed in a require but not in an import? Is there a way to achieve the same using import statements?
Thanks in advance
for the package to work with the ES6 import way, it has to be written to it, it has to be exported as eg:export default Logger and not module.exports = Logger, hope my answer helped you
I am trying to have the same module working with both Node.js and React. This works fine until I try to create a build application with React.
Here is what I am doing
var DummyTest = function DummyTest(){
this.hello=function(){
console.log("Hello Dummy Test");
}
}
module.exports = DummyTest;
In Node.js:
const DummyTest = require("./src/utils/dummy")
var test = new DummyTest();
test.hello();
In React:
import {DummyTest} from './utils/dummy';
var test = new DummyTest();
test.hello();
Perfect, works both on Web and Node.js.
But if I try to create a build environment:
Attempted import error: 'DummyTest' is not exported from './utils/dummy'.
export default can not be used because it must works also on Node.js .
Use
import * as DummyTest from './utils/dummy
...or depending on your bundler's configuration, just require it like you would in Node.
Having done a lot of research I cannot find a way to mock functions that are exported with no parent object. For example I'm trying to mock functions exported the following way:
module.exports = function thing(event) {};
OR in ES6
export function thing(event) {};
When importing these into a test file I try importing like this:
import {thing} from 'emvio-util-responses;
//call some function that calls thing()
spyOn(???, 'thing').and.returnValue({});
expect(???.thing).toHaveBeenCalled();
I have tried many ways of accomplishing this but the mock is not called.
Some suggest importing * and providing an alias as a parent object. like this:
import * as SomeObj from 'emvio-util-responses;
//call some function that calls thing()
spyOn(SomeObj , 'thing').and.returnValue({});
expect(SomeObj .thing).toHaveBeenCalled();
This doesn't work.
Others suggest using the window object
spyOn(window, 'thing').and.returnValue({});
But I'm in node :(.
When you use es6 modules instead CommonJS all exports are named so you may use:
export default (event) => {}
and then import & spy as
import * as SomeObj from 'emvio-util-responses'
...
beforeEach(() => {
spyOn(someObj, 'default')
});
So I have a React Native custom library that I made that has 2 modules made, moduleA and moduleB. How do I export them so that I can call both of the modules in my project?
Before when I had only one module it would work perfectly like this:
//Index.js file of my library
import { NativeModules } from 'react-native';
const { moduleA } = NativeModules;
export default moduleA;
and then in my React native project I could call it like this
//Home.js file of my project
import moduleA from 'custom_library';
moduleA.method(); //Works fine
But now that I have two modules, I'm not sure how to change the modules and the import such that both can be used. Is it even possible? The end goal that I want to be able to do is
//Home.js file of my project
import { moduleA, moduleB } from 'custom_library';
moduleA.method();
moduleB.method();
Sorry for the basic question, but I'm getting frustrated that nothing I've tried is really working.
Just use the export keyword. You will find more detailed examples here.
index.js of custom_library
import { NativeModules } from 'react-native';
const { moduleA, moduleB } = NativeModules;
export { moduleA, moduleB };
home.js
import { moduleA, moduleB } from 'custom_library';
moduleA.method();
moduleB.method();