fix: added-esm-like-tests

Author: Zaimwa9

.github/workflows/pull_request.yaml

@@ -35,3 +35,6 @@ jobs:
       - run: npm test
         env:
           CI: true
+      - run: npm run test:esm-build
+        env:
+          CI: true

package.json

@@ -51,6 +51,7 @@
   "scripts": {
     "lint": "prettier --write .",
     "test": "vitest --coverage --run",
+    "test:esm-build": "npm run build && ESM_BUILD=true vitest --config vitest.config.esm.ts --run",
     "test:watch": "vitest",
     "test:debug": "vitest --inspect-brk --no-file-parallelism --coverage",
     "prebuild": "rm -rf ./build",

tests/engine/unit/segments/segment_evaluators.test.ts

@@ -14,6 +14,8 @@ import {
     SegmentCondition1
 } from '../../../../flagsmith-engine/evaluation/models.js';
 
+const isEsmBuild = process.env.ESM_BUILD === 'true';
+
 // todo: work out how to implement this in a test function or before hook
 vi.mock('../../../../flagsmith-engine/utils/hashing', () => ({
     getHashedPercentageForObjIds: vi.fn(() => 1)
@@ -395,7 +397,8 @@ describe('getContextValue', () => {
     });
 });
 
-describe('percentage split operator', () => {
+// Skip in ESM build: vi.mock doesn't work with external modules
+describe.skipIf(isEsmBuild)('percentage split operator', () => {
     const mockContext: EvaluationContext = {
         environment: { key: 'env', name: 'Test Env' },
         identity: {

tests/sdk/flagsmith.test.ts

@@ -14,8 +14,12 @@ import { EnvironmentModel } from '../../flagsmith-engine/environments/models.js'
 import { BaseOfflineHandler } from '../../sdk/offline_handlers.js';
 import { Agent } from 'undici';
 
+const isEsmBuild = process.env.ESM_BUILD === 'true';
+
 vi.mock('../../sdk/polling_manager');
-test('test_flagsmith_starts_polling_manager_on_init_if_enabled', () => {
+
+// Skip in ESM build: vi.mock doesn't work with external modules
+test.skipIf(isEsmBuild)('test_flagsmith_starts_polling_manager_on_init_if_enabled', () => {
     new Flagsmith({
         environmentKey: 'ser.key',
         enableLocalEvaluation: true
@@ -32,7 +36,8 @@ test('test_flagsmith_local_evaluation_key_required', () => {
     }).toThrow('Using local evaluation requires a server-side environment key');
 });
 
-test('test_update_environment_sets_environment', async () => {
+// Skip in ESM build: instanceof fails across module boundaries
+test.skipIf(isEsmBuild)('test_update_environment_sets_environment', async () => {
     const flg = flagsmith({
         environmentKey: 'ser.key'
     });
@@ -513,7 +518,8 @@ test('getIdentityFlags succeeds if initial fetch failed then succeeded', async (
     expect(flags2.isFeatureEnabled('some_feature')).toBe(true);
 });
 
-test('get_user_agent_extracts_version_from_package_json', async () => {
+// Skip in ESM build: require() path resolution differs
+test.skipIf(isEsmBuild)('get_user_agent_extracts_version_from_package_json', async () => {
     const userAgent = getUserAgent();
     const packageJson = require('../../package.json');
 

tests/sdk/offline-handlers.test.ts

@@ -7,8 +7,10 @@ import * as offlineEnvironment from './data/offline-environment.json';
 vi.mock('fs');
 
 const offlineEnvironmentString = JSON.stringify(offlineEnvironment);
+const isEsmBuild = process.env.ESM_BUILD === 'true';
 
-test('local file handler', () => {
+// Skip in ESM build: instanceof fails across module boundaries
+test.skipIf(isEsmBuild)('local file handler', () => {
     const environmentDocumentFilePath = '/some/path/environment.json';
 
     // Mock the fs.readFileSync function to return environmentJson

vitest.config.esm.ts

@@ -0,0 +1,34 @@
+import { defineConfig } from 'vitest/config';
+import path from 'path';
+
+/**
+ * Vitest config for testing against the built ESM output.
+ * This catches CJS/ESM interop issues (like jsonpath) that don't surface
+ * when testing TypeScript source directly.
+ *
+ * Run with: npm run test:esm-build (after npm run build)
+ */
+export default defineConfig({
+    test: {
+        globals: true,
+        restoreMocks: true,
+        exclude: ['**/node_modules/**'],
+        server: {
+            deps: {
+                // Don't transform built ESM - test it as-is
+                external: [/build\/esm/]
+            }
+        }
+    },
+    resolve: {
+        alias: {
+            // Redirect source imports to built ESM output
+            '../../../flagsmith-engine': path.resolve(__dirname, 'build/esm/flagsmith-engine'),
+            '../../../../flagsmith-engine': path.resolve(__dirname, 'build/esm/flagsmith-engine'),
+            '../../../sdk': path.resolve(__dirname, 'build/esm/sdk'),
+            '../../../../sdk': path.resolve(__dirname, 'build/esm/sdk'),
+            '../../sdk': path.resolve(__dirname, 'build/esm/sdk'),
+            '../sdk': path.resolve(__dirname, 'build/esm/sdk'),
+        }
+    }
+});