accounts-frontend/src/services/request/PromiseMiddlewareLayer.test.ts

import sinon from 'sinon';
import expect from 'test/unexpected';

import PromiseMiddlewareLayer from 'services/request/PromiseMiddlewareLayer';

describe('PromiseMiddlewareLayer', () => {
  describe('#add()', () => {
    let layer;

    beforeEach(() => {
      layer = new PromiseMiddlewareLayer();
    });

    it('should have no middlewares by default', () => {
      expect(layer.middlewares, 'to have length', 0);
    });

    it('should add middleware into layer', () => {
      layer.add({});

      expect(layer.middlewares, 'to have length', 1);
    });

    it('throws if middleware is not object', () => {
      expect(() => layer.add(1), 'to throw', 'A middleware must be an object');
    });
  });

  describe('#run()', () => {
    it('should return promise', () => {
      const layer: any = new PromiseMiddlewareLayer();

      expect(layer.run('then'), 'to be a', Promise);
    });

    testAction('then');
    testAction('catch');

    function testAction(name) {
      describe(`run('${name}')`, () => {
        it('should run middleware', () => {
          const layer: any = new PromiseMiddlewareLayer();
          const middleware = {
            [name]: sinon
              .spy(() => Promise.resolve())
              .named(`middleware.${name}`),
          };

          layer.add(middleware);

          return layer.run(name).then(() => {
            expect(middleware[name], 'was called once');
          });
        });

        it('should pass data', () => {
          const layer: any = new PromiseMiddlewareLayer();
          const middleware = {
            [name]: sinon
              .spy(() => Promise.resolve())
              .named(`middleware.${name}`),
          };
          const data = {};

          layer.add(middleware);

          return layer.run(name, data).then(() => {
            expect(middleware[name], 'to have a call satisfying', [data]);
          });
        });

        it('should call multiple middlewares', async () => {
          const layer: any = new PromiseMiddlewareLayer();
          const initialValue = 'initialValue';
          const options = { foo: 'bar' };
          const firstMethod = name === 'catch' ? 'reject' : 'resolve';
          const middleware1 = {
            [name]: sinon
              .spy(() => (Promise[firstMethod] as any)('new data'))
              .named(`middleware1.${name}`),
          };
          const middleware2 = {
            [name]: sinon
              .spy(() => Promise.resolve('the last data'))
              .named(`middleware2.${name}`),
          };

          layer.add(middleware1);
          layer.add(middleware2);

          const resp = await layer.run(name, initialValue, options);

          expect(middleware1[name], 'to have a call satisfying', [
            initialValue,
            options,
          ]);
          expect(middleware2[name], 'to have a call satisfying', [
            'new data',
            options,
          ]);
          expect(resp, 'to equal', 'the last data');
        });
      });
    }

    it('should not call wrong actions', () => {
      const layer: any = new PromiseMiddlewareLayer();
      const middleware = {
        then: () => {},
        wrongAction: sinon
          .spy(() => Promise.resolve())
          .named('middleware.wrongAction'),
      };

      layer.add(middleware as any);

      return layer.run('then').then(() => {
        expect(middleware.wrongAction, 'was not called');
      });
    });

    it('should not call next catch middleware if previous was resolved', () => {
      const layer: any = new PromiseMiddlewareLayer();
      const middleware1 = {
        catch: () => Promise.resolve(),
      };
      const middleware2 = {
        catch: sinon.spy(() => {}).named('middleware2.catch'),
      };

      layer.add(middleware1);
      layer.add(middleware2);

      return layer.run('catch').then(() => {
        expect(middleware2.catch, 'was not called');
      });
    });

    it('should pass restart callback if any', () => {
      const layer: any = new PromiseMiddlewareLayer();
      const middleware = {
        catch: sinon.spy(() => Promise.resolve()).named('middleware.catch'),
      };
      const callback = async () => {};

      layer.add(middleware);

      return layer.run('catch', {}, {}, callback).then(() => {
        expect(middleware.catch, 'to have a call satisfying', [
          {},
          {},
          expect.it('to be', callback),
        ]);
      });
    });
  });
});