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refactor(experimental): extract the request cache logic into a base i…
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…mplementation
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@steveluscher
steveluscher committed Sep 23, 2023
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283 changes: 283 additions & 0 deletions packages/library/src/__tests__/cached-abortable-iterable-test.ts
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import { getCachedAbortableIterableFactory } from '../cached-abortable-iterable';

describe('getCachedAbortableIterableFactory', () => {
let asyncGenerator: jest.Mock<AsyncGenerator<unknown, void>>;
let factory: (...args: unknown[]) => Promise<AsyncIterable<unknown>>;
let getAbortSignalFromInputArgs: jest.Mock;
let getCacheKeyFromInputArgs: jest.Mock;
let getCacheEntryMissingError: jest.Mock;
let onCacheHit: jest.Mock;
let onCreateIterable: jest.Mock;
beforeEach(() => {
jest.useFakeTimers();
asyncGenerator = jest.fn().mockImplementation(async function* () {
yield await new Promise(() => {
/* never resolve */
});
});
getAbortSignalFromInputArgs = jest.fn().mockImplementation(() => new AbortController().signal);
getCacheKeyFromInputArgs = jest.fn().mockReturnValue('cache-key');
getCacheEntryMissingError = jest.fn();
onCacheHit = jest.fn();
onCreateIterable = jest.fn().mockResolvedValue({
[Symbol.asyncIterator]: asyncGenerator,
});
factory = getCachedAbortableIterableFactory({
getAbortSignalFromInputArgs,
getCacheEntryMissingError,
getCacheKeyFromInputArgs,
onCacheHit,
onCreateIterable,
});
});
it('reuses the same iterable for multiple invocations in the same runloop', async () => {
expect.assertions(1);
await Promise.all([factory('A'), factory('B')]);
expect(onCreateIterable).toHaveBeenCalledTimes(1);
});
it('reuses the same iterable for multiple invocations in different runloops', async () => {
expect.assertions(1);
await factory('A');
await factory('B');
expect(onCreateIterable).toHaveBeenCalledTimes(1);
});
it('reuses the same iterable so long as there is at least one non-aborted consumer', async () => {
expect.assertions(1);
const abortControllerA = new AbortController();
getAbortSignalFromInputArgs.mockReturnValue(abortControllerA.signal);
await factory('A');
await factory('B');
abortControllerA.abort();
await jest.runAllTimersAsync();
await factory('C');
expect(onCreateIterable).toHaveBeenCalledTimes(1);
});
it('reuses the same iterable even if a single subscription was aborted as many times as there are subscriptions', async () => {
expect.assertions(1);
const abortControllerA = new AbortController();
getAbortSignalFromInputArgs.mockReturnValueOnce(abortControllerA.signal);
await factory('A');
await factory('B');
abortControllerA.abort();
abortControllerA.abort();
await jest.runAllTimersAsync();
await factory('C');
expect(onCreateIterable).toHaveBeenCalledTimes(1);
});
it('reuses the same iterable so long as there is at least one non-aborted consumer at the end of the runloop, even if all of the existing ones are aborted', async () => {
expect.assertions(1);
const abortControllerA = new AbortController();
const abortControllerB = new AbortController();
getAbortSignalFromInputArgs.mockReturnValueOnce(abortControllerA.signal);
await factory('A');
getAbortSignalFromInputArgs.mockReturnValueOnce(abortControllerB.signal);
await factory('B');
abortControllerA.abort();
abortControllerB.abort();
await factory('C');
await jest.runAllTimersAsync();
expect(onCreateIterable).toHaveBeenCalledTimes(1);
});
it('creates a new connection when all of the prior subscriptions have been aborted', async () => {
expect.assertions(1);
const abortControllerA = new AbortController();
const abortControllerB = new AbortController();
getAbortSignalFromInputArgs.mockReturnValueOnce(abortControllerA.signal);
await factory('A');
getAbortSignalFromInputArgs.mockReturnValueOnce(abortControllerB.signal);
await factory('B');
abortControllerA.abort();
abortControllerB.abort();
// FIXME: Prefer async version of this timer runner. See https://github.com/jestjs/jest/issues/14549
jest.runAllTimers();
await factory('C');
expect(onCreateIterable).toHaveBeenCalledTimes(2);
});
it('creates a new connection for a message given that the prior one failed synchronously', async () => {
expect.assertions(2);
// First time fails synchronously.
onCreateIterable.mockImplementationOnce(() => {
throw new Error('o no');
});
try {
await factory('A');
} catch {
/* empty */
}
expect(onCreateIterable).toHaveBeenCalledTimes(1);
// Second time succeeds.
await factory('A');
expect(onCreateIterable).toHaveBeenCalledTimes(2);
});
it('creates a new connection for a message given that the prior one failed asynchronously', async () => {
expect.assertions(2);
// First time fails asynchronously.
onCreateIterable.mockRejectedValueOnce(new Error('o no'));
try {
await factory('A');
} catch {
/* empty */
}
expect(onCreateIterable).toHaveBeenCalledTimes(1);
// Second time succeeds.
await factory('A');
expect(onCreateIterable).toHaveBeenCalledTimes(2);
});
it('creates a new connection for a message given that the prior connection threw', async () => {
expect.assertions(2);
let killConnection;
asyncGenerator.mockImplementationOnce(async function* () {
yield await new Promise((_, reject) => {
killConnection = reject;
});
});
await factory('A');
expect(onCreateIterable).toHaveBeenCalledTimes(1);
// FIXME: https://github.com/microsoft/TypeScript/issues/11498
// eslint-disable-next-line @typescript-eslint/ban-ts-comment
// @ts-ignore
killConnection();
await jest.runAllTimersAsync();
await factory('A');
expect(onCreateIterable).toHaveBeenCalledTimes(2);
});
it('creates a new connection for a message given that prior connection returned', async () => {
expect.assertions(1);
let returnFromConnection;
asyncGenerator.mockImplementationOnce(async function* () {
try {
yield await new Promise((_, reject) => {
returnFromConnection = reject;
});
} catch {
return;
}
});
await factory('A');
// FIXME: https://github.com/microsoft/TypeScript/issues/11498
// eslint-disable-next-line @typescript-eslint/ban-ts-comment
// @ts-ignore
returnFromConnection();
await jest.runAllTimersAsync();
await factory('A');
expect(onCreateIterable).toHaveBeenCalledTimes(2);
});
it('calls `onCreateIterable` with the input args when no cached iterable is found', async () => {
expect.assertions(1);
await factory('A');
expect(onCreateIterable).toHaveBeenCalledWith(expect.any(AbortSignal), 'A');
});
it('calls `onCreateIterable` with an `AbortSignal` different than the one passed in', async () => {
expect.assertions(1);
const signal = new AbortController().signal;
getAbortSignalFromInputArgs.mockReturnValue(signal);
await factory('A');
expect(onCreateIterable.mock.lastCall[0]).not.toBe(signal);
});
it('does not call `onCacheHit` in the same runloop until the cached iterable is resolved', async () => {
expect.assertions(2);
let resolve;
onCreateIterable.mockImplementation(
() =>
new Promise(r => {
resolve = r;
})
);
Promise.all([factory('A'), factory('B')]);
expect(onCacheHit).not.toHaveBeenCalled();
await jest.runAllTimersAsync();
const iterable = asyncGenerator();
// FIXME: https://github.com/microsoft/TypeScript/issues/11498
// eslint-disable-next-line @typescript-eslint/ban-ts-comment
// @ts-ignore
resolve(iterable);
await jest.runAllTimersAsync();
expect(onCacheHit).toHaveBeenCalledWith(iterable, 'B');
});
it('calls `onCacheHit` in the same runloop when the cached iterable is already resolved', async () => {
expect.assertions(1);
const iterable = asyncGenerator();
onCreateIterable.mockReturnValue(iterable);
Promise.all([factory('A'), factory('B')]);
expect(onCacheHit).toHaveBeenCalledWith(iterable, 'B');
});
it('does not call `onCacheHit` in different runloops until the cached iterable is resolved', async () => {
expect.assertions(2);
let resolve;
onCreateIterable.mockImplementation(
() =>
new Promise(r => {
resolve = r;
})
);
factory('A');
await jest.runAllTimersAsync();
factory('B');
await jest.runAllTimersAsync();
expect(onCacheHit).not.toHaveBeenCalled();
const iterable = asyncGenerator();
// FIXME: https://github.com/microsoft/TypeScript/issues/11498
// eslint-disable-next-line @typescript-eslint/ban-ts-comment
// @ts-ignore
resolve(iterable);
await jest.runAllTimersAsync();
expect(onCacheHit).toHaveBeenCalledWith(iterable, 'B');
});
it('calls `onCacheHit` in different runloops when the cached iterable is already resolved', async () => {
expect.assertions(1);
const iterable = asyncGenerator();
onCreateIterable.mockReturnValue(iterable);
await factory('A');
await factory('B');
expect(onCacheHit).toHaveBeenCalledWith(iterable, 'B');
});
describe('given payloads that produce the same cache key', () => {
beforeEach(() => {
getCacheKeyFromInputArgs.mockReturnValue('cache-key');
});
it('reuses the same iterable for all payloads in the same runloop', async () => {
expect.assertions(1);
await Promise.all([factory('A'), factory('B')]);
expect(onCreateIterable).toHaveBeenCalledTimes(1);
});
it('reuses the same iterable for all payloads in different runloops', async () => {
expect.assertions(1);
await factory('A');
await factory('B');
expect(onCreateIterable).toHaveBeenCalledTimes(1);
});
});
describe('given payloads that produce different cache keys', () => {
beforeEach(() => {
let shardKey = 0;
getCacheKeyFromInputArgs.mockImplementation(() => `${++shardKey}`);
});
it('creates a connection for each payload in the same runloop', async () => {
expect.assertions(1);
await Promise.all([factory('A'), factory('B')]);
expect(onCreateIterable).toHaveBeenCalledTimes(2);
});
it('creates a connection for each payload in different runloops', async () => {
expect.assertions(1);
await factory('A');
await factory('B');
expect(onCreateIterable).toHaveBeenCalledTimes(2);
});
});
describe('given payloads that produce the cache key `undefined`', () => {
beforeEach(() => {
getCacheKeyFromInputArgs.mockReturnValue(undefined);
});
it('creates a connection for each payload in the same runloop', async () => {
expect.assertions(1);
await Promise.all([factory('A'), factory('B')]);
expect(onCreateIterable).toHaveBeenCalledTimes(2);
});
it('creates a connection for each payload in different runloops', async () => {
expect.assertions(1);
await factory('A');
await factory('B');
expect(onCreateIterable).toHaveBeenCalledTimes(2);
});
});
});
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