Add Jest configuration and unit tests for interlinearizer feature

- Introduced Jest configuration in `jest.config.ts` and setup file in `jest.setup.ts` for testing.
- Added unit tests for the `interlinearizer.web-view` component , `InterlinearXmlParser`, and `main` in `src/__tests__/`.
- Created mocks for static assets and dependencies to facilitate testing.
- Updated ESLint and Prettier configurations to ignore Jest-related files and directories.
- Enhanced README to document the new testing structure and usage.

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: alex-rawlings-yyc

.eslintignore

@@ -29,6 +29,10 @@ dist
 release
 temp-build
 
+# Jest
+__mocks__
+coverage
+
 # generated files
 package-lock.json
 

.eslintrc.js

@@ -155,6 +155,14 @@ module.exports = {
         'import/no-self-import': 'off',
       },
     },
+    {
+      // Jest globals (describe, it, expect, etc.) so ESLint does not report no-undef
+      files: ['**/*.test.{ts,tsx}', '**/*.spec.{ts,tsx}', '**/__tests__/**/*.{ts,tsx}'],
+      plugins: ['jest'],
+      env: {
+        'jest/globals': true,
+      },
+    },
   ],
   parserOptions: {
     ecmaVersion: 2022,
@@ -163,7 +171,7 @@ module.exports = {
     tsconfigRootDir: __dirname,
     createDefaultProgram: true,
   },
-  plugins: ['@typescript-eslint', 'no-type-assertion', 'no-null'],
+  plugins: ['@typescript-eslint', 'jest', 'no-type-assertion', 'no-null'],
   settings: {
     'import/resolver': {
       typescript: {

.gitignore

@@ -14,6 +14,7 @@ dist
 release
 dist-ssr
 *.local
+coverage
 
 # formatting and linting
 .eslintcache

.prettierignore

@@ -29,6 +29,10 @@ dist
 release
 temp-build
 
+# Jest
+__mocks__
+coverage
+
 # generated files
 package-lock.json
 

.stylelintignore

@@ -29,6 +29,10 @@ dist
 release
 temp-build
 
+# Jest
+__mocks__
+coverage
+
 # generated files
 package-lock.json
 

README.md

@@ -99,6 +99,8 @@ The general file structure for an extension is as follows:
   - `*.web-view.tsx` files will be treated as React WebViews
   - `*.web-view.scss` files provide styles for WebViews
   - `*.web-view.html` files are a conventional way to provide HTML WebViews (no special functionality)
+  - `src/__tests__/` contains unit tests (Jest) for the extension, including parser tests and web-view tests
+- `__mocks__/` contains Jest mocks for the PAPI, file modules, and test fixtures used by tests in `src/__tests__/`
 - `assets/` contains asset files the extension and its WebViews can retrieve using the `papi-extension:` protocol, as well as textual descriptions in various languages. It is copied into the build folder
   - `assets/displayData.json` contains (optionally) a path to the extension's icon file as well as text for the extension's display name, short summary, and path to the full description file
   - `assets/descriptions/` contains textual descriptions of the extension in various languages

__mocks__/@papi/backend.js

@@ -0,0 +1,33 @@
+/**
+ * Jest manual mock for @papi/backend. Jest auto-applies this when tests call
+ * jest.mock('@papi/backend'). Provides papi and logger so main.ts can be unit-tested without the
+ * real Platform API.
+ *
+ * Main.ts uses: import papi, { logger } from '@papi/backend'
+ */
+
+const mockRegisterWebViewProvider = jest.fn().mockResolvedValue({ dispose: jest.fn() });
+const mockOpenWebView = jest.fn().mockResolvedValue(undefined);
+const mockLogger = {
+  debug: jest.fn(),
+  error: jest.fn(),
+  info: jest.fn(),
+  warn: jest.fn(),
+};
+
+const papi = {
+  webViewProviders: {
+    registerWebViewProvider: mockRegisterWebViewProvider,
+  },
+  webViews: {
+    openWebView: mockOpenWebView,
+  },
+};
+
+module.exports = {
+  __mockRegisterWebViewProvider: mockRegisterWebViewProvider,
+  __mockOpenWebView: mockOpenWebView,
+  __mockLogger: mockLogger,
+  default: papi,
+  logger: mockLogger,
+};

__mocks__/fileMock.js

@@ -0,0 +1,8 @@
+/**
+ * Jest mock for static asset imports (images, fonts, etc.). Importing e.g. `logo.png` in tests will
+ * receive this string instead of running file loaders. Mirrors webpack's asset/inline and
+ * asset/resource handling in webpack.config.base.
+ *
+ * @see https://jestjs.io/docs/webpack#handling-static-assets
+ */
+module.exports = 'test-file-stub';

__mocks__/interlinearXmlContent.js

@@ -0,0 +1,9 @@
+/**
+ * Jest mock for webpack ?raw XML import. Exports the contents of test-data/Interlinear_en_MAT.xml
+ * so interlinearizer.web-view.tsx can parse it in unit tests without webpack.
+ */
+const fs = require('fs');
+const path = require('path');
+
+const xmlPath = path.join(__dirname, '..', 'test-data', 'Interlinear_en_MAT.xml');
+module.exports = fs.readFileSync(xmlPath, 'utf-8');

__mocks__/papi-backend.js

@@ -0,0 +1,33 @@
+/**
+ * Jest mock for @papi/backend. Provides papi and logger so main.ts can be unit-tested without
+ * loading the real Platform API.
+ *
+ * Main.ts uses: import papi, { logger } from '@papi/backend' With esModuleInterop, default export
+ * must be the papi object; logger as named export.
+ */
+
+const mockRegisterWebViewProvider = jest.fn().mockResolvedValue({ dispose: jest.fn() });
+const mockOpenWebView = jest.fn().mockResolvedValue(undefined);
+const mockLogger = {
+  debug: jest.fn(),
+  error: jest.fn(),
+  info: jest.fn(),
+  warn: jest.fn(),
+};
+
+const papi = {
+  webViewProviders: {
+    registerWebViewProvider: mockRegisterWebViewProvider,
+  },
+  webViews: {
+    openWebView: mockOpenWebView,
+  },
+};
+
+module.exports = {
+  __mockRegisterWebViewProvider: mockRegisterWebViewProvider,
+  __mockOpenWebView: mockOpenWebView,
+  __mockLogger: mockLogger,
+  default: papi,
+  logger: mockLogger,
+};