Add ES module compliance test and CI integration

Add automated testing to catch ES module import issues:
- New strict ES module test using Node.js directly
- Updated CI pipeline to run ES module compliance check
- Added npm script for ES module testing

This prevents future regressions where missing .js extensions
would break the SDK when consumed by ES module projects.

Author: GabiGrin

.github/workflows/unit-tests.yml

@@ -25,3 +25,6 @@ jobs:
 
       - name: Run unit tests
         run: npm run test:unit
+
+      - name: Test ES module compliance
+        run: npm run test:esm

package.json

@@ -11,9 +11,10 @@
   "scripts": {
     "build": "tsc",
     "lint": "eslint src",
-    "test": "vitest run",
+    "test": "npm run build && vitest run",
     "test:unit": "vitest run tests/unit",
     "test:e2e": "vitest run tests/e2e",
+    "test:esm": "npm run build && node test-esm-strict.mjs",
     "test:watch": "vitest",
     "test:coverage": "vitest run --coverage",
     "prepublishOnly": "npm run build"

test-esm-strict.mjs

@@ -0,0 +1,16 @@
+/**
+ * Strict ES module test - runs with Node.js directly
+ * This will fail if imports don't have proper .js extensions
+ */
+import { createClient } from './dist/index.js';
+
+console.log('✅ ES module import successful');
+console.log('createClient:', typeof createClient);
+
+const client = createClient({
+  apiKey: 'test-key',
+  baseURL: 'https://api.test.com'
+});
+
+console.log('✅ Client creation successful');
+process.exit(0);

tests/esm-compliance.test.js

@@ -0,0 +1,21 @@
+/**
+ * Test to verify ES module compliance by importing the built SDK
+ * This test runs against the compiled output to catch import issues
+ */
+import { createClient } from '../dist/index.js';
+import { describe, it, expect } from 'vitest';
+
+describe('ES Module Compliance', () => {
+  it('should import the SDK successfully from built dist', () => {
+    expect(createClient).toBeDefined();
+    expect(typeof createClient).toBe('function');
+  });
+
+  it('should create a client instance', () => {
+    const client = createClient({
+      apiKey: 'test-key',
+      baseURL: 'https://api.test.com'
+    });
+    expect(client).toBeDefined();
+  });
+});