失敗をユースケースの結果として扱う

exercises/result-errors.test.tsimport { err } from "neverthrow";import { describe, expect, expectTypeOf, it } from "vitest";import { createApp } from "../src/app.js";import type {  Appointment,  CheckedIn,  Scheduled,} from "../src/domain/appointment/index.js";import { AppointmentId } from "../src/domain/appointment/index.js";import { OwnerId } from "../src/domain/owner/index.js";import { PetId } from "../src/domain/pet/index.js";import { VeterinarianId } from "../src/domain/appointment/index.js";import type { Dependencies } from "../src/useCase/dependencies.js";import {  ensureAppointmentFound,  ensureCheckedIn,} from "../src/useCase/errors.js";import type { StartExaminationError } from "../src/useCase/errors.js"; // 要件: 予約なしと状態不正を、kindで区別できる診察開始エラーとして定義してください。import { startExamination } from "../src/useCase/startExamination.js";import type { startExaminationNoticeCodes } from "../src/web/routes.js"; // 要件: 診察開始エラーのkindをキーにした通知対応表を公開してください。import { clinicFixture } from "../../fixtures/clinic.js";const appointmentId = AppointmentId.parse(clinicFixture.appointmentId);const veterinarianId = VeterinarianId.parse(clinicFixture.veterinarianId);const scheduled = {  kind: "Scheduled",  appointmentId,  petId: PetId.parse(clinicFixture.petId),  ownerId: OwnerId.parse(clinicFixture.ownerId),  scheduledAt: clinicFixture.scheduledAt,  reason: "skin check",} as const satisfies Scheduled;const checkedIn = {  ...scheduled,  kind: "CheckedIn",  checkedInAt: clinicFixture.checkedInAt,} as const satisfies CheckedIn;const input = {  appointmentId,  veterinarianId,  examinationStartedAt: "2026-08-30T06:30:00.000Z",} as const;type AppointmentUnavailable = Readonly<{  kind: "AppointmentUnavailable";}>;type ErrorWithNewVariant = StartExaminationError | AppointmentUnavailable;describe("Step 1: InvalidAppointmentState を値として返す", () => {  it("CheckedIn でない予約でも例外を投げない", () => {    try {      const result = ensureCheckedIn(scheduled);      expect(result).toEqual(err({        kind: "InvalidAppointmentState",        actual: "Scheduled",      }));    } catch {      throw new Error("要件未達: 来院済みでない予約は状態不正として返してください。");    }  });});describe("Step 2: AppointmentNotFound を値として返す", () => {  it("予約が見つからなくても例外を投げない", () => {    try {      const result = ensureAppointmentFound(undefined, appointmentId);      expect(result).toEqual(err({ kind: "AppointmentNotFound", appointmentId }));    } catch {      throw new Error("要件未達: 見つからない予約は予約なしとして返してください。");    }  });});describe("Step 3: andThen pipeline が失敗理由を運ぶ", () => {  it("予約なしを保持し、保存しない", () => {    let saveCalls = 0;    const deps = createDependencies(undefined, {      onSave: () => {        saveCalls += 1;      },    });    try {      const result = startExamination(deps)(input);      expect(result).toEqual(err({ kind: "AppointmentNotFound", appointmentId }));      expect(saveCalls).toBe(0);    } catch {      throw new Error("要件未達: 予約なしの理由を保持し、保存を実行しないでください。");    }  });  it("状態不正の後も保存しない", () => {    let saveCalls = 0;    const deps = createDependencies(scheduled, {      onSave: () => {        saveCalls += 1;      },    });    try {      const result = startExamination(deps)(input);      expect(result).toEqual(err({        kind: "InvalidAppointmentState",        actual: "Scheduled",      }));      expect(saveCalls).toBe(0);    } catch {      throw new Error("要件未達: 状態不正の理由を保持し、保存を実行しないでください。");    }  });  it("保存障害を業務エラーへ変換せず例外として伝える", () => {    const saveFailure = new Error("database unavailable");    const deps = createDependencies(checkedIn, {      onSave: () => {        throw saveFailure;      },    });    expect(() => startExamination(deps)(input)).toThrow(saveFailure);  });});describe("Step 4: 呼び出し側が業務エラーを漏れなく処理する", () => {  it("状態不正を専用noticeへ変換する", async () => {    const response = await post(      createApp(),      `/appointments/${clinicFixture.appointmentId}/start-examination`,    );    if (response.headers.get("location") !== "/?notice=invalid-state") {      throw new Error("要件未達: 状態不正を専用のお知らせへ変換してください。");    }  });  it("予約なしを専用noticeへ変換する", async () => {    const response = await post(      createApp(),      "/appointments/99999999-9999-4999-8999-999999999999/start-examination",    );    expect(response.headers.get("location")).toBe("/?notice=not-found");  });  it("診察開始エラーのkindを通知対応表で漏れなく扱う", () => {    expectTypeOf<keyof typeof startExaminationNoticeCodes>()      .toEqualTypeOf<StartExaminationError["kind"]>(); // 要件: 通知対応表は診察開始エラーのkindを過不足なくキーにしてください。  });  it("業務エラーを追加すると通知対応表の不足を型で検出する", () => {    expectTypeOf<keyof typeof startExaminationNoticeCodes>()      .not.toEqualTypeOf<ErrorWithNewVariant["kind"]>(); // 要件: 業務エラーを追加したら通知対応表にもキーを追加してください。  });});const createDependencies = (  resolved: Appointment | undefined,  observer: Readonly<{    onSave?: () => void;  }> = {},): Dependencies => ({  resolver: { resolveById: () => resolved },  store: {    save: () => {      observer.onSave?.();    },  },});const post = async (  app: ReturnType<typeof createApp>,  path: string,): Promise<Response> =>  app.request(path, {    method: "POST",    headers: {      Accept: "application/json",      "X-Inertia": "true",      "X-Inertia-Version": "1",    },  });