initial mocking of the os module works

__mocks__/os.js

@@ -0,0 +1,5 @@
+import { vi } from "vitest";
+
+export default {
+    type: vi.fn(() => 'Linux')
+}

package.json

@@ -28,6 +28,7 @@
   },
   "devDependencies": {
     "node-gyp": "^10.0.1",
+    "vite": "^5.0.0",
     "vitest": "^0.34.6"
   }
 }

test/00-core.test.mjs

@@ -1,6 +1,11 @@
-import { describe, it } from "vitest";
+import os from "os";
+import { describe, it, vi } from "vitest";
 
 describe("libgpiod miscellaneous bindings", () => {
+  it("should be running in a mocked Linux", async ({ expect }) => {
+    expect(os.type()).toBe('Linux');
+  });
+
   it("should be available", async ({ expect }) => {
     expect(gpiod.available()).toBeTruthy();
   });

test/setup.mjs

@@ -1,13 +1,13 @@
 import { gpiod } from "../index.mjs";
 
-import { afterAll, beforeAll } from 'vitest';
+import { afterEach, beforeEach } from 'vitest';
 
-beforeAll(() => {
-    if (!globalThis.gpiod) {
-        globalThis.gpiod = gpiod;
-    }
+vi.mock("os");
+
+beforeEach(async () => {
+    if (!globalThis.gpiod) globalThis.gpiod = gpiod;
 });
 
-afterAll(() => {
+afterEach(() => {
     delete globalThis.gpiod;
 });