diff --git a/src/index.ts b/src/index.ts index 5de224a14..2c18b7a37 100644 --- a/src/index.ts +++ b/src/index.ts @@ -189,6 +189,7 @@ export * from './util/errors/UnsupportedMediaTypeHttpError'; // Util/Handlers export * from './util/handlers/AsyncHandler'; +export * from './util/handlers/ParallelHandler'; export * from './util/handlers/SequenceHandler'; export * from './util/handlers/UnsupportedAsyncHandler'; export * from './util/handlers/WaterfallHandler'; diff --git a/src/util/handlers/ParallelHandler.ts b/src/util/handlers/ParallelHandler.ts new file mode 100644 index 000000000..3d78fb88b --- /dev/null +++ b/src/util/handlers/ParallelHandler.ts @@ -0,0 +1,23 @@ +import { AsyncHandler } from './AsyncHandler'; + +/** + * A composite handler that executes handlers in parallel. + */ +export class ParallelHandler extends AsyncHandler { + private readonly handlers: AsyncHandler[]; + + public constructor(handlers: AsyncHandler[]) { + super(); + this.handlers = [ ...handlers ]; + } + + public async canHandle(input: TIn): Promise { + // eslint-disable-next-line @typescript-eslint/promise-function-async + await Promise.all(this.handlers.map((handler): Promise => handler.canHandle(input))); + } + + public async handle(input: TIn): Promise { + // eslint-disable-next-line @typescript-eslint/promise-function-async + return Promise.all(this.handlers.map((handler): Promise => handler.handle(input))); + } +} diff --git a/test/unit/util/handlers/ParallelHandler.test.ts b/test/unit/util/handlers/ParallelHandler.test.ts new file mode 100644 index 000000000..3d8792ba7 --- /dev/null +++ b/test/unit/util/handlers/ParallelHandler.test.ts @@ -0,0 +1,100 @@ +import type { AsyncHandler } from '../../../../src/util/handlers/AsyncHandler'; +import { ParallelHandler } from '../../../../src/util/handlers/ParallelHandler'; + +describe('A ParallelHandler', (): void => { + const handlers: jest.Mocked>[] = [ + { + canHandle: jest.fn(), + handle: jest.fn().mockResolvedValue('0'), + }, + { + canHandle: jest.fn(), + handle: jest.fn().mockResolvedValue('1'), + }, + { + canHandle: jest.fn(), + handle: jest.fn().mockResolvedValue('2'), + }, + ] as any; + const composite: ParallelHandler = new ParallelHandler(handlers); + + afterEach(jest.clearAllMocks); + + describe('canHandle', (): void => { + it('succeeds if all handlers succeed.', async(): Promise => { + await expect(composite.canHandle('abc')).resolves.toBeUndefined(); + + expect(handlers[0].canHandle).toHaveBeenCalledTimes(1); + expect(handlers[1].canHandle).toHaveBeenCalledTimes(1); + expect(handlers[2].canHandle).toHaveBeenCalledTimes(1); + + expect(handlers[0].canHandle).toHaveBeenCalledWith('abc'); + expect(handlers[1].canHandle).toHaveBeenCalledWith('abc'); + expect(handlers[2].canHandle).toHaveBeenCalledWith('abc'); + }); + + it('fails if one handler fails.', async(): Promise => { + const error = new Error('failure'); + handlers[1].canHandle.mockRejectedValueOnce(error); + await expect(composite.canHandle('abc')).rejects.toThrow(error); + }); + }); + + describe('handle', (): void => { + it('succeeds if all handlers succeed.', async(): Promise => { + await expect(composite.handle('abc')).resolves.toEqual([ '0', '1', '2' ]); + + expect(handlers[0].handle).toHaveBeenCalledTimes(1); + expect(handlers[1].handle).toHaveBeenCalledTimes(1); + expect(handlers[2].handle).toHaveBeenCalledTimes(1); + + expect(handlers[0].handle).toHaveBeenCalledWith('abc'); + expect(handlers[1].handle).toHaveBeenCalledWith('abc'); + expect(handlers[2].handle).toHaveBeenCalledWith('abc'); + }); + + it('fails if one handler fails.', async(): Promise => { + const error = new Error('failure'); + handlers[1].handle.mockRejectedValueOnce(error); + await expect(composite.handle('abc')).rejects.toThrow(error); + }); + }); + + describe('handleSafe', (): void => { + it('succeeds if all handlers succeed.', async(): Promise => { + await expect(composite.handleSafe('abc')).resolves.toEqual([ '0', '1', '2' ]); + + expect(handlers[0].canHandle).toHaveBeenCalledTimes(1); + expect(handlers[1].canHandle).toHaveBeenCalledTimes(1); + expect(handlers[2].canHandle).toHaveBeenCalledTimes(1); + + expect(handlers[0].canHandle).toHaveBeenCalledWith('abc'); + expect(handlers[1].canHandle).toHaveBeenCalledWith('abc'); + expect(handlers[2].canHandle).toHaveBeenCalledWith('abc'); + + expect(handlers[0].handle).toHaveBeenCalledTimes(1); + expect(handlers[1].handle).toHaveBeenCalledTimes(1); + expect(handlers[2].handle).toHaveBeenCalledTimes(1); + + expect(handlers[0].handle).toHaveBeenCalledWith('abc'); + expect(handlers[1].handle).toHaveBeenCalledWith('abc'); + expect(handlers[2].handle).toHaveBeenCalledWith('abc'); + }); + + it('fails if one canHandle fails.', async(): Promise => { + const error = new Error('failure'); + handlers[1].canHandle.mockRejectedValueOnce(error); + await expect(composite.handleSafe('abc')).rejects.toThrow(error); + + expect(handlers[0].handle).toHaveBeenCalledTimes(0); + expect(handlers[1].handle).toHaveBeenCalledTimes(0); + expect(handlers[2].handle).toHaveBeenCalledTimes(0); + }); + + it('fails if one handle fails.', async(): Promise => { + const error = new Error('failure'); + handlers[1].handle.mockRejectedValueOnce(error); + await expect(composite.handleSafe('abc')).rejects.toThrow(error); + }); + }); +});