feat(02-1): add example

Author: rgomezcasas

02-demeter_tell_dont_ask/1-demeter/src/Codelyber.ts

@@ -0,0 +1,9 @@
+import { UserFullName } from "./UserFullName";
+import { UserId } from "./UserId";
+
+export class User {
+	constructor(
+		public readonly id: UserId,
+		public readonly fullName: UserFullName,
+	) {}
+}

02-demeter_tell_dont_ask/1-demeter/src/User.ts

@@ -0,0 +1,9 @@
+import { UserLastName } from "./UserLastName";
+import { UserName } from "./UserName";
+
+export class UserFullName {
+	constructor(
+		public readonly name: UserName,
+		public readonly lastName: UserLastName,
+	) {}
+}

02-demeter_tell_dont_ask/1-demeter/src/UserFullName.ts

@@ -0,0 +1,15 @@
+import { UserRepository } from "./UserRepository";
+
+export class UserFullNameByIdFinder {
+	constructor(private readonly repository: UserRepository) {}
+
+	find(id: string): string {
+		const user = this.repository.search(id);
+
+		if (user === null) {
+			throw new Error(`The user ${id} does not exist`);
+		}
+
+		return `${user.fullName.name.value} ${user.fullName.lastName.value}`;
+	}
+}

02-demeter_tell_dont_ask/1-demeter/src/UserFullNameByIdFinder.ts

@@ -0,0 +1,7 @@
+export class UserId {
+	constructor(public readonly value: string) {
+		if (value.length !== 36) {
+			throw new Error("The user id must be a valid uuid");
+		}
+	}
+}

02-demeter_tell_dont_ask/1-demeter/src/UserId.ts

@@ -0,0 +1,7 @@
+export class UserLastName {
+	constructor(public readonly value: string) {
+		if (value.length < 3) {
+			throw new Error("The user last must be at least 3 characters long");
+		}
+	}
+}

02-demeter_tell_dont_ask/1-demeter/src/UserLastName.ts

@@ -0,0 +1,7 @@
+export class UserName {
+	constructor(public readonly value: string) {
+		if (value.length < 3) {
+			throw new Error("The user name must be at least 3 characters long");
+		}
+	}
+}

02-demeter_tell_dont_ask/1-demeter/src/UserName.ts

@@ -0,0 +1,5 @@
+import { User } from "./User";
+
+export interface UserRepository {
+	search(id: string): User | null;
+}

02-demeter_tell_dont_ask/1-demeter/src/UserRepository.ts

@@ -0,0 +1,45 @@
+import { User } from "../src/User";
+import { UserFullName } from "../src/UserFullName";
+import { UserFullNameByIdFinder } from "../src/UserFullNameByIdFinder";
+import { UserId } from "../src/UserId";
+import { UserLastName } from "../src/UserLastName";
+import { UserName } from "../src/UserName";
+import { UserRepository } from "../src/UserRepository";
+
+describe("UserFullNameByIdFinder", () => {
+	const validUuid = "550e8400-e29b-41d4-a716-446655440000";
+
+	const mockUserRepository: UserRepository = {
+		search: jest.fn((id: string) => {
+			if (id === validUuid) {
+				return new User(
+					new UserId(validUuid),
+					new UserFullName(new UserName("Javier"), new UserLastName("Ferrer")),
+				);
+			}
+
+			return null;
+		}),
+	};
+
+	it("throw an error searching a non existing user", () => {
+		const nonExistingUuid = "550e8400-e29b-41d4-a716-446655440001";
+
+		const finder = new UserFullNameByIdFinder(mockUserRepository);
+
+		expect(() => {
+			finder.find(nonExistingUuid);
+		}).toThrow(`The user ${nonExistingUuid} does not exist`);
+
+		expect(mockUserRepository.search).toHaveBeenCalledWith(nonExistingUuid);
+	});
+
+	it("return an existing user full name", () => {
+		const finder = new UserFullNameByIdFinder(mockUserRepository);
+
+		const result = finder.find(validUuid);
+
+		expect(result).toBe("Javier Ferrer");
+		expect(mockUserRepository.search).toHaveBeenCalledWith(validUuid);
+	});
+});