Add Yarn Version to the Cache Key

src/index.mjs

@@ -10,6 +10,12 @@ async function main() {
     await yarn.enable();
   });
 
+  const version = await core.group("Getting Yarn version", async () => {
+    const version = await yarn.version();
+    core.info(`Yarn version: ${version}`);
+    return version;
+  });
+
   const lockFileHash = await core.group(
     "Calculating lock file hash",
     async () => {
@@ -26,7 +32,7 @@ async function main() {
   const cachePaths = [".yarn", ".pnp.cjs", ".pnp.loader.mjs"];
   const cacheKey =
     lockFileHash !== undefined
-      ? `yarn-install-action-${os.type()}-${lockFileHash}`
+      ? `yarn-install-action-${os.type()}-${version}-${lockFileHash}`
       : undefined;
 
   if (cacheKey !== undefined) {

src/yarn.mjs

@@ -1,4 +1,4 @@
-import { exec } from "@actions/exec";
+import { exec, getExecOutput } from "@actions/exec";
 
 async function disableGlobalCache() {
   return exec("corepack", [
@@ -27,4 +27,9 @@ async function install() {
   return exec("corepack", ["yarn", "install"], { env });
 }
 
-export default { disableGlobalCache, enable, install };
+async function version() {
+  const res = await getExecOutput("corepack", ["yarn", "--version"]);
+  return res.stdout.trim();
+}
+
+export default { disableGlobalCache, enable, install, version };

src/yarn.test.mjs

@@ -2,6 +2,7 @@ import { jest } from "@jest/globals";
 
 jest.unstable_mockModule("@actions/exec", () => ({
   exec: jest.fn(),
+  getExecOutput: jest.fn(),
 }));
 
 beforeEach(() => {
@@ -50,3 +51,17 @@ it("should install package using Yarn", async () => {
     },
   });
 });
+
+it("should get Yarn version", async () => {
+  const { getExecOutput } = await import("@actions/exec");
+  const yarn = (await import("./yarn.mjs")).default;
+
+  getExecOutput.mockResolvedValue({ stdout: "1.2.3" });
+
+  const version = await yarn.version();
+
+  expect(getExecOutput).toHaveBeenCalledTimes(1);
+  expect(getExecOutput).toHaveBeenCalledWith("corepack", ["yarn", "--version"]);
+
+  expect(version).toEqual("1.2.3");
+});