Testing Utilities

Marmotte ships lightweight Vitest helpers for tests that need to work with the filesystem.

import { withTmpDir, createTmpDir, createTmpDirSync } from "marmotte/vitest";

See the API reference for full details.

withTmpDir — auto-managed temporary directory

The most common helper. Call it at the top level of a describe block to get a reference to a temporary directory that is created before the suite runs and deleted after it finishes.

import { describe, it, expect } from "vitest";
import { withTmpDir } from "marmotte/vitest";
import { writeFile, readFile } from "fs/promises";
import { join } from "path";

describe("my file-writing logic", () => {
  const tmp = withTmpDir();

  it("writes and reads a file", async () => {
    const file = join(tmp.path, "hello.txt");
    await writeFile(file, "hello");
    expect(await readFile(file, "utf8")).toBe("hello");
  });
});

withTmpDir registers beforeAll / afterAll hooks in the current Vitest context. The path getter throws if accessed outside of a test (i.e. before beforeAll has run).

Note: Access tmp.path only inside it / test blocks, never at the describe level.

createTmpDir and createTmpDirSync

Use these when you need a temporary directory outside of a Vitest hook context, or when you want to manage the lifecycle yourself.

import { createTmpDir, createTmpDirSync } from "marmotte/vitest";
import { rm } from "fs/promises";

// Async version
const dir = await createTmpDir();
// … use dir …
await rm(dir, { recursive: true });

// Sync version
const dir2 = createTmpDirSync();
// … use dir2 …

Both delegate to Node's fs.mkdtemp / fs.mkdtempSync using the OS temp directory as the base.