add-test

name	add-test
description	Use when adding tests for new or existing code in gdevelop-mcp. Tests use vitest, live in test/, and follow the safety-first priorities laid out in .claude/rules/testing.md.

Adding a test

Checklist

• Identify the module under test (src/core/<topic>.ts).
• Open or create test/<topic>.test.ts.
• Import from ../src/core/<topic>.js (the .js extension is required for ESM).
• If you need a project fixture, use minimalValidProject() from test/fixtures.ts and mutate it; don't hand-write a large JSON.
• Cover at least: happy path + one error path.
• For tools that write files, use mkdtempSync(join(tmpdir(), "...")) to isolate fixtures. Each it block creates its own.
• Run npm test. All tests must pass.

Template

import { describe, it, expect, beforeEach } from "vitest";
import { thingUnderTest } from "../src/core/<topic>.js";
import { minimalValidProject } from "./fixtures.js";

describe("thingUnderTest", () => {
  it("does the happy path", () => {
    const result = thingUnderTest(minimalValidProject());
    expect(result).toBe(/* ... */);
  });

  it("returns an error on bad input", () => {
    expect(() => thingUnderTest(null as unknown as never)).toThrow();
  });
});

Async tests

it("awaits things correctly", async () => {
  const r = await asyncThing();
  expect(r).toBeDefined();
});

it("rejects on bad input", async () => {
  await expect(asyncThing(/* bad */)).rejects.toThrow(/error message regex/);
});

Filesystem tests

import { mkdtempSync, writeFileSync, readFileSync } from "node:fs";
import { tmpdir } from "node:os";
import { join } from "node:path";

let projectPath: string;
beforeEach(() => {
  const dir = mkdtempSync(join(tmpdir(), "my-test-"));
  projectPath = join(dir, "game.json");
  writeFileSync(projectPath, JSON.stringify(minimalValidProject()), "utf-8");
});

When NOT to add a test

• For thin glue (the tool handler in src/index.ts) — test the underlying function in src/core/* instead.
• For 3rd-party behavior (don't test that fetch works).
• For things that need a live GDevelop install or network (those are manual / CI-tier).

See .claude/rules/testing.md for full rules.