Got tests to fail with __dirname. Updated tests to use ESM. Updated test code to be ESM compatible

Author: David Buzinski

jest.config.ts

@@ -1,21 +1,22 @@
 export default {
+    clearMocks: true,
     testEnvironment: "node",
     collectCoverage: true,
     testMatch: ["**/*.test.ts"],
     transform: {
         "^.+\\.[jt]s$": [
             "ts-jest",
             {
+                useESM: true,
                 diagnostics: {
                     ignoreCodes: [151002],
                 },
             },
         ],
     },
+    extensionsToTreatAsEsm: ['.ts'],
     transformIgnorePatterns: ["node_modules/(?!(@actions)/)"],
     moduleNameMapper: {
         "^(\\.{1,2}/.*)\\.js$": "$1",
-        "^@actions/core$": "<rootDir>/node_modules/@actions/core/lib/core.js",
-        "^@actions/exec$": "<rootDir>/node_modules/@actions/exec/lib/exec.js",
     },
 };

package.json

@@ -12,7 +12,7 @@
         "build": "tsc",
         "prepare": "npm run build",
         "package": "ncc build --minify",
-        "test": "jest",
+        "test": "NODE_OPTIONS='--experimental-vm-modules' jest",
         "all": "npm test && npm run build && npm run package",
         "ci": "npm run clean && npm ci --ignore-scripts && npm run all"
     },

src/buildSummary.unit.test.ts

@@ -1,16 +1,24 @@
 // Copyright 2024-26 The MathWorks, Inc.
 
-import * as buildSummary from "./buildSummary.js";
-import * as core from "@actions/core";
+import {jest, describe, it, expect, beforeEach} from "@jest/globals";
 
-jest.mock('@actions/core', () => ({
+jest.unstable_mockModule('@actions/core', () => ({
     summary: {
         addTable: jest.fn().mockReturnThis(),
         addHeading: jest.fn().mockReturnThis(),
         write: jest.fn().mockReturnThis(),
     },
 }));
 
+const core = await import("@actions/core");
+const buildSummary = await import("./buildSummary.js");
+
+beforeEach(() => {
+    (core.summary.addTable as jest.Mock).mockReturnThis();
+    (core.summary.addHeading as jest.Mock).mockReturnThis();
+    (core.summary.write as jest.Mock).mockReturnThis();
+});
+
 describe('summaryGeneration', () => {
     it('should process and return summary rows for valid JSON with different task statuses', () => {
         const mockBuildSummary = JSON.stringify([

src/matlab.ts

@@ -3,6 +3,7 @@
 import { promises as fs } from "fs";
 import * as os from "os";
 import * as path from "path";
+import { fileURLToPath } from "url";
 import { v4 as uuid } from "uuid";
 import * as script from "./script.js";
 
@@ -103,7 +104,8 @@ export function getRunMATLABCommandScriptPath(platform: string, architecture: st
         default:
             throw new Error(`This action is not supported on ${platform} runners using the ${architecture} architecture.`);
     }
-    const rmcPath = path.join(__dirname, "bin", platformDir, `run-matlab-command${ext}`);
+    const dirname = path.dirname(fileURLToPath(import.meta.url));
+    const rmcPath = path.join(dirname, "bin", platformDir, `run-matlab-command${ext}`);
     return rmcPath;
 
 }

src/matlab.unit.test.ts

@@ -1,8 +1,10 @@
 // Copyright 2020-2026 The MathWorks, Inc.
 
+import {jest, describe, it, expect, afterEach} from "@jest/globals";
 import { promises as fs } from "fs";
 import * as path from "path";
 import * as matlab from "./matlab.js";
+import type { ExecFn } from "./matlab.js";
 
 afterEach(() => {
     jest.resetAllMocks();
@@ -62,7 +64,7 @@ describe("run command", () => {
 
     it("ideally works", async () => {
         const chmod = jest.spyOn(fs, "chmod");
-        const execFn = jest.fn();
+        const execFn = jest.fn<ExecFn>();
 
         chmod.mockResolvedValue(undefined);
         execFn.mockResolvedValue(0);
@@ -73,21 +75,21 @@ describe("run command", () => {
 
     it("ideally works with arguments", async () => {
         const chmod = jest.spyOn(fs, "chmod");
-        const execFn = jest.fn();
+        const execFn = jest.fn<ExecFn>();
 
         chmod.mockResolvedValue(undefined);
         execFn.mockResolvedValue(0);
 
         const actual = matlab.runCommand(helperScript, platform, architecture, execFn, ["-nojvm", "-logfile", "file"]);
         await expect(actual).resolves.toBeUndefined();
-        expect(execFn.mock.calls[0][1][1]).toBe("-nojvm");
-        expect(execFn.mock.calls[0][1][2]).toBe("-logfile");
-        expect(execFn.mock.calls[0][1][3]).toBe("file");
+        expect(execFn.mock.calls[0][1]![1]).toBe("-nojvm");
+        expect(execFn.mock.calls[0][1]![2]).toBe("-logfile");
+        expect(execFn.mock.calls[0][1]![3]).toBe("file");
     });
 
     it("fails when chmod fails", async () => {
         const chmod = jest.spyOn(fs, "chmod");
-        const execFn = jest.fn();
+        const execFn = jest.fn<ExecFn>();
 
         chmod.mockRejectedValue(null);
 
@@ -99,7 +101,7 @@ describe("run command", () => {
 
     it("fails when the execFn fails", async () => {
         const chmod = jest.spyOn(fs, "chmod");
-        const execFn = jest.fn();
+        const execFn = jest.fn<ExecFn>();
 
         chmod.mockResolvedValue(undefined);
         execFn.mockRejectedValue(null);
@@ -112,7 +114,7 @@ describe("run command", () => {
 
     it("fails when the execFn has a non-zero exit code", async () => {
         const chmod = jest.spyOn(fs, "chmod");
-        const execFn = jest.fn();
+        const execFn = jest.fn<ExecFn>();
 
         chmod.mockResolvedValue(undefined);
         execFn.mockResolvedValue(1);

src/script.ts

@@ -1,6 +1,7 @@
 // Copyright 2020-2025 The MathWorks, Inc.
 
 import * as path from "path";
+import { fileURLToPath } from "url";
 
 /**
  * Generate MATLAB command for changing directories, adding plugins to path and calling a command in it.
@@ -10,7 +11,8 @@ import * as path from "path";
  * @returns MATLAB command.
  */
 export function prepare(command: string): string {
-    const pluginsPath = path.join(__dirname, "plugins").replaceAll("'","''");
+    const dirname = path.dirname(fileURLToPath(import.meta.url));
+    const pluginsPath = path.join(dirname, "plugins").replaceAll("'","''");
     return `cd(getenv('MW_ORIG_WORKING_FOLDER')); ` +
         `addpath('` + pluginsPath + `'); `
         + command;

src/script.unit.test.ts

@@ -1,13 +1,16 @@
 // Copyright 2020-2026 The MathWorks, Inc.
 
+import {describe, it, expect} from "@jest/globals";
 import * as script from "./script.js";
 import * as path from "path";
+import { fileURLToPath } from "url";
 
 describe("call generation", () => {
     it("ideally works", () => {
         // I know what your thinking
         const testCommand = "disp('hello world')";
-        const pluginsPath = path.join(__dirname, "plugins").replaceAll("'","''");
+        const dirname = path.dirname(fileURLToPath(import.meta.url));
+        const pluginsPath = path.join(dirname, "plugins").replaceAll("'","''");
         const expectedString = `cd(getenv('MW_ORIG_WORKING_FOLDER')); addpath('` + pluginsPath + `'); ${testCommand}`;
 
         expect(script.prepare(testCommand)).toMatch(expectedString);