Language

class Language {
  private code: string;
 
  constructor(code: string) {
    if (!this.isValidLanguageCode(code)) {
      throw new Error(
        "Invalid language code. Please provide a valid language or locale code."
      );
    }
    this.code = code;
  }
 
  equals(other: Language): boolean {
    return this.code === other.code;
  }
 
  toString(): string {
    return this.code;
  }
 
  private isValidLanguageCode(code: string): boolean {
    // You can implement your language code validation logic here.
    // For simplicity, we're not checking the code format in this example.
    // In a real application, you might use a specific pattern or validate against a list of valid codes.
    return true;
  }
}
 
// Example usage
const language = new Language("en-US");
 
// You can also use the Language class as a type
function greet(language: Language): string {
  if (language.equals(new Language("en-US"))) {
    return "Hello!";
  } else if (language.equals(new Language("fr-FR"))) {
    return "Bonjour!";
  } else {
    return "Hola!";
  }
}

import { Language } from "./Language"; // Adjust the import path as per your project structure
 
describe("Language", () => {
  describe("constructor", () => {
    it("should create a Language instance with a valid language code", () => {
      const language = new Language("en-US");
      expect(language).toBeDefined();
    });
 
    it("should throw an error for an invalid language code", () => {
      expect(() => new Language("invalid_code")).toThrow();
    });
  });
 
  describe("equals", () => {
    it("should return true when comparing two Language instances with the same language code", () => {
      const language1 = new Language("en-US");
      const language2 = new Language("en-US");
      expect(language1.equals(language2)).toBe(true);
    });
 
    it("should return false when comparing two Language instances with different language codes", () => {
      const language1 = new Language("en-US");
      const language2 = new Language("fr-FR");
      expect(language1.equals(language2)).toBe(false);
    });
  });
 
  describe("toString", () => {
    it("should return the string representation of the Language", () => {
      const language = new Language("en-US");
      expect(language.toString()).toBe("en-US");
    });
  });
});