CommunitySolidServer/test/unit/util/handlers/UnionHandler.test.ts

import type { AsyncHandler } from '../../../../src/util/handlers/AsyncHandler';
import { UnionHandler } from '../../../../src/util/handlers/UnionHandler';

class SimpleUnionHandler extends UnionHandler<AsyncHandler<any, string>> {
  public constructor(handlers: AsyncHandler<any, any>[], requireAll?: boolean) {
    super(handlers, requireAll);
  }

  protected async combine(results: string[]): Promise<string> {
    return results.join('');
  }
}

describe('A UnionHandler', (): void => {
  const input = { data: 'text' };
  let handlers: jest.Mocked<AsyncHandler<any, string>>[];
  let handler: SimpleUnionHandler;

  beforeEach(async(): Promise<void> => {
    handlers = [
      { canHandle: jest.fn(), handle: jest.fn().mockResolvedValue('a') } as any,
      { canHandle: jest.fn(), handle: jest.fn().mockResolvedValue('b') } as any,
    ];

    handler = new SimpleUnionHandler(handlers);
  });

  it('can handle a request if at least one extractor can handle it.', async(): Promise<void> => {
    await expect(handler.canHandle(input)).resolves.toBeUndefined();

    handlers[0].canHandle.mockRejectedValue(new Error('bad request'));
    await expect(handler.canHandle(input)).resolves.toBeUndefined();

    handlers[1].canHandle.mockRejectedValue(new Error('bad request'));
    await expect(handler.canHandle(input)).rejects.toThrow('bad request');

    await expect(handler.handleSafe(input)).rejects.toThrow('bad request');
  });

  it('requires all handlers to support the input if requireAll is true.', async(): Promise<void> => {
    handler = new SimpleUnionHandler(handlers, true);
    await expect(handler.canHandle(input)).resolves.toBeUndefined();

    handlers[0].canHandle.mockRejectedValue(new Error('bad request'));
    await expect(handler.canHandle(input)).rejects.toThrow('bad request');

    await expect(handler.handleSafe(input)).rejects.toThrow('bad request');
  });

  it('calls all handlers that support the input.', async(): Promise<void> => {
    handlers[0].canHandle.mockRejectedValue(new Error('bad request'));
    await expect(handler.handle(input)).resolves.toBe('b');
    await expect(handler.handleSafe(input)).resolves.toBe('b');
  });

  it('calls all handlers if requireAll is true.', async(): Promise<void> => {
    handler = new SimpleUnionHandler(handlers, true);
    await expect(handler.handleSafe(input)).resolves.toBe('ab');

    // `handle` call does not need to check `canHandle` values anymore
    handlers[0].canHandle.mockRejectedValue(new Error('bad request'));
    await expect(handler.handle(input)).resolves.toBe('ab');
  });
});