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import TappablePromise from '~/lib/utils/tappable_promise';
describe('TappablePromise', () => {
it('allows a promise to have a progress indicator', () => {
const pseudoProgress = [0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1];
const progressCallback = jest.fn();
const promise = new TappablePromise((tap, resolve) => {
pseudoProgress.forEach(tap);
resolve('done');
return 'returned value';
});
return promise
.tap(progressCallback)
.then((val) => {
expect(val).toBe('done');
expect(val).not.toBe('returned value');
expect(progressCallback).toHaveBeenCalledTimes(pseudoProgress.length);
pseudoProgress.forEach((progress, index) => {
expect(progressCallback).toHaveBeenNthCalledWith(index + 1, progress);
});
})
.catch(() => {});
});
it('resolves with the value returned by the callback', () => {
const promise = new TappablePromise((tap) => {
tap(0.5);
return 'test';
});
return promise
.tap((progress) => {
expect(progress).toBe(0.5);
})
.then((value) => {
expect(value).toBe('test');
});
});
it('allows a promise to be rejected', () => {
const promise = new TappablePromise((tap, resolve, reject) => {
reject(new Error('test error'));
});
return promise.catch((e) => {
expect(e.message).toBe('test error');
});
});
it('rejects the promise if the callback throws an error', () => {
const promise = new TappablePromise(() => {
throw new Error('test error');
});
return promise.catch((e) => {
expect(e.message).toBe('test error');
});
});
});
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