Add unit tests for Context class

[Copilot]

The Context class had no test coverage. This adds a full unit test suite using Node's built-in node:test framework (no new dependencies required — Node 24's native TypeScript stripping handles .ts files directly).

Changes

• test/context.test.ts — 45 tests across 16 describe suites covering every public method:

  • Initial state (default pets, users, orders)
  • Pet CRUD: addPet, updatePet, getPetById, deletePet, findPetsByStatus, findPetsByTags
  • User CRUD: addUser, getUserByUsername, updateUser, deleteUser
  • Order CRUD: placeOrder, getOrderById, deleteOrder
  • getInventory — including mutation reflection

• package.json — replaces the "No tests yet" placeholder with node --test test/**/*.test.ts

Example

describe("addPet", () => {
  it("assigns a new id to the added pet", () => {
    const pet = context.addPet({ name: "Rex", photoUrls: [] });
    assert.ok(typeof pet.id === "number");
  });

  it("increments the id for each new pet", () => {
    const first = context.addPet({ name: "Rex", photoUrls: [] });
    const second = context.addPet({ name: "Fido", photoUrls: [] });
    assert.equal(second.id, (first.id as number) + 1);
  });
});