project-inter-server/test/loaders/ApiBasedRepositoryLoaderTests.test.ts

import { beforeEach, describe, expect, it, jest, test } from "@jest/globals";
import { ApiBasedRepositoryLoader, ApiResponseError } from "../../src/loaders/ApiBasedRepositoryLoader";
import { UnoptimizedInMemoryRepository } from "../../src/repositories/UnoptimizedInMemoryRepository";
import { fetchSystemDataSuccessfulResponse } from "../jsonSnapshots/fetchSystemData/fetchSystemDataSuccessfulResponse";
import { fetchSystemDataFailedResponse } from "../jsonSnapshots/fetchSystemData/fetchSystemDataFailedResponse";
import { fetchRouteDataSuccessfulResponse } from "../jsonSnapshots/fetchRouteData/fetchRouteDataSuccessfulResponse";

/**
 * Function to update behavior of the global `fetch` function.
 * Note that the Passio GO API returns status code 200 for failed responses.
 * @param obj
 * @param status
 */
function updateGlobalFetchMockJson(
  obj: any,
  status: number = 200
) {
  // @ts-ignore
  global.fetch = jest.fn(() => {
    return Promise.resolve({
      json: () => Promise.resolve(obj),
      status,
      ok: status.toString().startsWith("2"), // 200-level codes are OK
    })
  }) as jest.Mock;
}

/**
 * Reset the global fetch function mock's JSON to return an empty object.
 * @param obj
 */
function resetGlobalFetchMockJson() {
  updateGlobalFetchMockJson({});
}

async function assertAsyncCallbackThrowsApiResponseError(callback: () => Promise<any>) {
  await expect(callback).rejects.toThrow(ApiResponseError);
}

describe("ApiBasedRepositoryLoader", () => {
  let loader: ApiBasedRepositoryLoader;

  beforeEach(() => {
    loader = new ApiBasedRepositoryLoader(new UnoptimizedInMemoryRepository());
    resetGlobalFetchMockJson();
  });

  describe("fetchAndUpdateSystemData", () => {
    it("updates system data in repository if response received", async () => {
      const numberOfSystemsInResponse = fetchSystemDataSuccessfulResponse.all.length;
      updateGlobalFetchMockJson(fetchSystemDataSuccessfulResponse);

      await loader.fetchAndUpdateSystemData();

      const systems = await loader.repository.getSystems();
      if (loader.supportedSystemIds.length < numberOfSystemsInResponse) {
        expect(systems).toHaveLength(loader.supportedSystemIds.length);
      } else {
        expect(systems).toHaveLength(numberOfSystemsInResponse);
      }
    });

    it("throws the correct error if the API response contains no data", async () => {
      updateGlobalFetchMockJson(fetchSystemDataFailedResponse);

      await assertAsyncCallbackThrowsApiResponseError(async () => {
        await loader.fetchAndUpdateSystemData();
      });
    });

    it("throws the correct error if HTTP status code is not 200", async () => {
      updateGlobalFetchMockJson(fetchSystemDataFailedResponse, 400);

      await assertAsyncCallbackThrowsApiResponseError(async () => {
        await loader.fetchAndUpdateSystemData();
      });
    });
  });


  describe("fetchAndUpdateRouteDataForExistingSystemsInRepository", () => {
    // TODO
    // Add a test case to ensure that fetchAndUpdateRouteDataForSystemId
    // was called for every available system ID
  });

  describe("fetchAndUpdateRouteDataForSystemId", () => {
    it("updates route data in repository if there are systems and response received", async () => {
      updateGlobalFetchMockJson(fetchRouteDataSuccessfulResponse);

      await loader.fetchAndUpdateRouteDataForSystemId("263");

      const routes = await loader.repository.getRoutesBySystemId("263");

      expect(routes.length).toEqual(fetchRouteDataSuccessfulResponse.all.length)
    });

    it("throws the correct error if the API response contains no data", async () => {
      // The Passio API returns some invalid JSON if there is no data,
      // so simulate a JSON parsing error

      // @ts-ignore
      global.fetch = jest.fn(() => {
        return Promise.resolve({
          json: () => Promise.reject(new SyntaxError("Unable to parse JSON")),
          status: 200,
          ok: true,
        })
      }) as jest.Mock;

      await assertAsyncCallbackThrowsApiResponseError(async () => {
        await loader.fetchAndUpdateRouteDataForSystemId("263");
      });
    });
  });

  describe("fetchAndUpdateStopAndPolylineDataForRoutesInExistingSystems", () => {
    it("updates stop and polyline data if there are systems and response received", async () => {

    });

    it("throws the correct error if the API response contains no data", async () => {

    })
  });

  describe("fetchAndUpdateShuttleDataForExistingSystems", () => {
    it("updates shuttle data in repository if there are systems and response received", async () => {

    });

    it("throws the correct error if the API response contains no data", async () => {

    });
  });

  describe("fetchAndUpdateEtaDataForExistingSystems", () => {
    it("updates shuttle data in repository if there are systems and response received", async () => {

    });

    it("throws the correct error if the API response contains no data", async () => {

    });
  });
});