exponential-backoff-retry.spec.ts

exponential-backoff-retry.spec.ts

import { fakeAsync, tick } from '@angular/core/testing';
import { of, throwError } from 'rxjs';
import { mergeMap } from 'rxjs/operators';
import {
	exponentialBackoffRetry,
	RETRY_COUNT,
	RETRY_TIME,
} from './exponential-backoff-retry';

describe('exponentialBackoffRetry', () => {
	it('should retry http GET with exponential backoff', fakeAsync(() => {
		let callCount = 0;

		of(() => {})
			.pipe(
				mergeMap(() => {
					callCount = callCount + 1;
					return throwError(() => new Error('Some error'));
				}),
				exponentialBackoffRetry(RETRY_COUNT, RETRY_TIME),
			)
			.subscribe({
				error: () => {
					// silence error in test
				},
			});

		tick(RETRY_TIME);
		tick(RETRY_TIME * 4);
		tick(RETRY_TIME * 9);

		expect(callCount).toBe(RETRY_COUNT + 1);
	}));
});