Reintroduce Unit Testing Using Jest

.eslintrc.json

@@ -12,6 +12,12 @@
       "env": {
         "node": true
       }
+    },
+    {
+      "files": ["**/*.test.*"],
+      "env": {
+        "jest": true
+      }
     }
   ]
 }

.github/workflows/test.yaml

@@ -28,6 +28,26 @@ jobs:
       - name: Check Lint
         run: corepack yarn lint
 
+  test-package:
+    name: Test Package
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4.1.1
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4.0.2
+        with:
+          node-version: latest
+
+      - name: Install Dependencies
+        uses: threeal/yarn-install-action@v1.0.0
+
+      - name: Test Package
+        run: corepack yarn test
+        env:
+          NODE_OPTIONS: --experimental-vm-modules
+
   test-action:
     name: Test Action
     runs-on: ${{ matrix.os }}-latest

jest.config.json

@@ -0,0 +1,3 @@
+{
+  "testMatch": ["**/*.test.*"]
+}

package.json

@@ -4,7 +4,8 @@
   "scripts": {
     "build": "ncc build src/index.mjs",
     "format": "prettier --write --cache . !dist",
-    "lint": "eslint --ignore-path .gitignore ."
+    "lint": "eslint --ignore-path .gitignore .",
+    "test": "jest"
   },
   "dependencies": {
     "@actions/cache": "^3.2.4",
@@ -15,6 +16,7 @@
   "devDependencies": {
     "@vercel/ncc": "^0.38.1",
     "eslint": "^8.56.0",
+    "jest": "^29.7.0",
     "prettier": "^3.2.5"
   },
   "packageManager": "yarn@4.1.0"

src/yarn.test.mjs

@@ -0,0 +1,52 @@
+import { jest } from "@jest/globals";
+
+jest.unstable_mockModule("@actions/exec", () => ({
+  exec: jest.fn(),
+}));
+
+beforeEach(() => {
+  jest.clearAllMocks();
+});
+
+it("should disable Yarn global cache", async () => {
+  const { exec } = await import("@actions/exec");
+  const yarn = (await import("./yarn.mjs")).default;
+
+  await yarn.disableGlobalCache();
+
+  expect(exec).toHaveBeenCalledTimes(1);
+  expect(exec).toHaveBeenCalledWith("corepack", [
+    "yarn",
+    "config",
+    "set",
+    "enableGlobalCache",
+    "false",
+  ]);
+});
+
+it("should enable Yarn", async () => {
+  const { exec } = await import("@actions/exec");
+  const yarn = (await import("./yarn.mjs")).default;
+
+  await yarn.enable();
+
+  expect(exec).toHaveBeenCalledTimes(1);
+  expect(exec).toHaveBeenCalledWith("corepack", ["enable", "yarn"]);
+});
+
+it("should install package using Yarn", async () => {
+  const { exec } = await import("@actions/exec");
+  const yarn = (await import("./yarn.mjs")).default;
+
+  await yarn.install();
+
+  expect(exec).toHaveBeenCalledTimes(1);
+  expect(exec).toHaveBeenCalledWith("corepack", ["yarn", "install"], {
+    env: {
+      ...process.env,
+      GITHUB_ACTIONS: "",
+      FORCE_COLOR: "true",
+      CI: "",
+    },
+  });
+});