Jest does not seem to be detecting my mock calls in the catch block. Yet, if don't mock the method handleError, I'll receive an error. I have tried multiple ways of doing the returned rejected promise but no luck so far.
I've tried callbacks, Promise.reject, Promise((res, rej) => {})
Code being tested:
module.exports = class PresetDropdown {
constructor (Api, objectId, titleSort) {
this.Api = Api;
this.objectId; = objectId;
this.presets = [];
}
handleError (err) {
console.log(err)
// more functionality
}
get () {
this.Api.getMany(this.objectId)
.then((data) => {
this.handleEmpty(data);
this.isError = false;
})
.catch((err) => {
this.isError = true;
this.handleError(err);
});
}
};
Test (Jest):
test('Expect call from handleError after reject promise', async () => {
// assemble
// return the class
const Module = getModule();
const mockRejectedPromise = jest.fn(() => {
return Promise.reject(Error(mockError));
});
mockApi.getMany = mockRejectedPromise;
const module = new Module(mockApi, '1', null);
const mockHandleError = jest.fn(() => {});
PresetTemplate.handleError = mockHandleError;
// act
await PresetTemplate.get(mockScope);
// assert
expect(mockHandleError).toHaveBeenCalledTimes(1); // DOES NOT DETECT CALL
// Test CASE FAILS HERE ^
});
Since PresetDropdown class accept an Api object, you can create a mocked Api object and pass it to the class. Then mock resolved/rejected value for Api.getMany() method, so that you can test different code branches.
E.g.
presetDropdown.js:
module.exports = class PresetDropdown {
constructor(Api, objectId, titleSort) {
this.Api = Api;
this.objectId = objectId;
this.presets = [];
}
handleError(err) {
console.log(err);
}
handleEmpty(data) {
console.log(data);
}
get() {
return this.Api.getMany(this.objectId)
.then((data) => {
this.handleEmpty(data);
this.isError = false;
})
.catch((err) => {
this.isError = true;
this.handleError(err);
});
}
};
presetDropdown.test.js:
const PresetDropdown = require('./presetDropdown');
describe('71164955', () => {
test('should handle data', async () => {
const mockApi = {
getMany: jest.fn().mockResolvedValueOnce('fake data'),
};
const instance = new PresetDropdown(mockApi, '1');
await instance.get();
expect(instance.isError).toBeFalsy();
});
test('should handle error', async () => {
const mockError = new Error('fake error');
const mockApi = {
getMany: jest.fn().mockRejectedValueOnce(mockError),
};
const instance = new PresetDropdown(mockApi, '1');
await instance.get();
expect(instance.isError).toBeTruthy();
});
});
Test result:
PASS stackoverflow/71164955/presetDropdown.test.js
71164955
✓ should handle data (14 ms)
✓ should handle error (3 ms)
console.log
fake data
at PresetDropdown.handleEmpty (stackoverflow/71164955/presetDropdown.js:11:13)
console.log
Error: fake error
at Object.<anonymous> (/Users/dulin/workspace/github.com/mrdulin/jest-v26-codelab/stackoverflow/71164955/presetDropdown.test.js:12:23)
at Object.asyncJestTest (/Users/dulin/workspace/github.com/mrdulin/jest-v26-codelab/node_modules/jest-jasmine2/build/jasmineAsyncInstall.js:106:37)
at /Users/dulin/workspace/github.com/mrdulin/jest-v26-codelab/node_modules/jest-jasmine2/build/queueRunner.js:45:12
at new Promise (<anonymous>)
at mapper (/Users/dulin/workspace/github.com/mrdulin/jest-v26-codelab/node_modules/jest-jasmine2/build/queueRunner.js:28:19)
at /Users/dulin/workspace/github.com/mrdulin/jest-v26-codelab/node_modules/jest-jasmine2/build/queueRunner.js:75:41
at processTicksAndRejections (internal/process/task_queues.js:93:5)
at PresetDropdown.handleError (stackoverflow/71164955/presetDropdown.js:8:13)
Test Suites: 1 passed, 1 total
Tests: 2 passed, 2 total
Snapshots: 0 total
Time: 1.311 s