feat: add explicit extension support when using Typescript and ESM

lib/cli.js

@@ -81,6 +81,28 @@ exports.run = async function () {
 };
 
 
+internals.addTsEsmHook = function () {
+
+    const Module = require('module');
+
+    const originalResolveFilename = Module._resolveFilename;
+
+    Module._resolveFilename = function (request, parent, ...rest) {
+
+        if (request.endsWith('.js') && (parent.filename.endsWith('.ts') || parent.filename.endsWith('.tsx'))) {
+            const target = Path.join(parent.path, request);
+            const tsEquivalent = `${target.slice(0, -3)}.ts`;
+
+            if (!Fs.existsSync(target) && Fs.existsSync(tsEquivalent)) {
+                return tsEquivalent;
+            }
+        }
+
+        return originalResolveFilename.call(this, request, parent, ...rest);
+    };
+};
+
+
 internals.traverse = async function (paths, options) {
 
     let nextPath = null;
@@ -141,6 +163,10 @@ internals.traverse = async function (paths, options) {
 
     const scripts = [];
 
+    if (options.typescript && testFiles.some(([, defaultToESM]) => defaultToESM)) {
+        internals.addTsEsmHook();
+    }
+
     for (const [unresolvedFile, defaultToESM] of testFiles) {
 
         global._labScriptRun = false;

test/cli_typescript_esm/api.ts

@@ -0,0 +1,8 @@
+export * from './types.js';
+
+export function add(a: number, b: number) {
+
+    return a + b;
+}
+
+export const X = new (Date || Date)(); // $lab:coverage:ignore$

test/cli_typescript_esm/error.ts

@@ -0,0 +1,12 @@
+import { expect } from '@hapi/code';
+import * as _Lab from '../../test_runner/index.js';
+
+const { describe, it } = exports.lab = _Lab.script();
+
+describe('Test CLI', () => {
+
+    it('adds two numbers together', () => {
+
+        expect(1 + 1).to.equal(4);
+    });
+});

test/cli_typescript_esm/package.json

@@ -0,0 +1 @@
+{ "type": "module" }

test/cli_typescript_esm/simple.ts

@@ -0,0 +1,20 @@
+import { expect } from '@hapi/code';
+import * as _Lab from '../../test_runner/index.js';
+
+import { add } from './api.js';
+
+
+const { describe, it } = exports.lab = _Lab.script();
+
+describe('Test CLI', () => {
+
+    it('adds two numbers together', () => {
+
+        expect(add(1, 1)).to.equal(2);
+    });
+
+    it('subtracts two numbers', () => {
+
+        expect(add(2, - 2)).to.equal(0);
+    });
+});

test/cli_typescript_esm/tsconfig.json

@@ -0,0 +1,8 @@
+{
+    "compilerOptions": {
+        "target": "es2021",
+        "module": "commonjs",
+        "moduleResolution": "node",
+        "removeComments": true
+    }
+}

test/cli_typescript_esm/types.ts

@@ -0,0 +1 @@
+export type Test = string;

test/reporters.js

@@ -123,7 +123,7 @@ describe('Reporter', () => {
         expect(code).to.equal(0);
         expect(output).to.equal(await Fs.readFile(filename, 'utf8'));
 
-        await Fs.rmdir(folder, { recursive: true });
+        await Fs.rm(folder, { recursive: true });
     });
 
     it('outputs to a file with output is passed as an array and reporter is an array', async () => {

test/typescript.js

@@ -32,6 +32,18 @@ describe('TypeScript', () => {
         expect(result.output).to.contain('2 tests complete');
     });
 
+    it('supports TypeScript with ESM', async () => {
+
+        process.chdir(Path.join(__dirname, 'cli_typescript_esm'));
+        const result = await RunCli(['simple.ts', '-m', '2000', '--typescript']);
+        expect(result.errorOutput).to.equal('');
+        expect(result.code).to.equal(0);
+        expect(result.output).to.contain('2 tests complete');
+
+        // Ensure scripts are run together, not independently
+        expect(result.output.split('Test duration').length - 1).to.equal(1);
+    });
+
     it('handles errors', async () => {
 
         process.chdir(Path.join(__dirname, 'cli_typescript'));