Add detect package manager util function

src/utils.test.ts

@@ -1,6 +1,11 @@
-import { expect, test, describe } from "vitest";
-import { checkWorkingDirectory, getNpxCmd, semverCompare } from "./utils";
 import path from "node:path";
+import { describe, expect, test } from "vitest";
+import {
+	checkWorkingDirectory,
+	detectPackageManager,
+	getNpxCmd,
+	semverCompare,
+} from "./utils";
 
 test("getNpxCmd ", async () => {
 	process.env.RUNNER_OS = "Windows";
@@ -43,3 +48,25 @@ describe("checkWorkingDirectory", () => {
 		);
 	});
 });
+
+describe("detectPackageManager", () => {
+	test("should return name of package manager for current workspace", () => {
+		expect(detectPackageManager()).toBe("npm");
+	});
+
+	test("should return npm if package-lock.json exists", () => {
+		expect(detectPackageManager("test/fixtures/npm")).toBe("npm");
+	});
+
+	test("should return yarn if yarn.lock exists", () => {
+		expect(detectPackageManager("test/fixtures/yarn")).toBe("yarn");
+	});
+
+	test("should return pnpm if pnpm-lock.yaml exists", () => {
+		expect(detectPackageManager("test/fixtures/pnpm")).toBe("pnpm");
+	});
+
+	test("should return null if no package manager is detected", () => {
+		expect(detectPackageManager("test/fixtures/empty")).toBe(null);
+	});
+});

src/utils.ts

@@ -33,3 +33,20 @@ export function checkWorkingDirectory(workingDirectory = ".") {
 		throw new Error(`Directory ${workingDirectory} does not exist.`);
 	}
 }
+
+export type PackageManager = "npm" | "yarn" | "pnpm";
+
+export function detectPackageManager(
+	workingDirectory = ".",
+): PackageManager | null {
+	if (existsSync(path.join(workingDirectory, "package-lock.json"))) {
+		return "npm";
+	}
+	if (existsSync(path.join(workingDirectory, "yarn.lock"))) {
+		return "yarn";
+	}
+	if (existsSync(path.join(workingDirectory, "pnpm-lock.yaml"))) {
+		return "pnpm";
+	}
+	return null;
+}