ci(lit): add browser-based integration testing to lit explorer (a2ui-project#1545)

Sets up the integration testing infrastructure for the Lit renderer explorer application.

* Adds Karma and Jasmine to run ChromeHeadless tests
* Expands the Lit test workflow to run the new integration tests (previously this was only running unit tests)
* Adds a sample integration test to see how everything works together

Author: ditman

.github/workflows/lit_build_and_test.yml

@@ -33,31 +33,36 @@ permissions:
 jobs:
   build-and-test:
     runs-on: ubuntu-latest
-
+    strategy:
+      matrix:
+        task: [unit, integration]
     steps:
       - uses: actions/checkout@v6
-
       - name: Set up Node.js
         uses: actions/setup-node@v6
         with:
           node-version: "22"
 
-      - name: Install web_core dependencies
-        working-directory: ./renderers/web_core
-        run: npm i
-
+      # Unit tests need to build the Lit renderer
       - name: Build web_core
+        if: matrix.task == 'unit'
         working-directory: ./renderers/web_core
-        run: npm run build
-
-      - name: Install Lit renderer dependencies
-        working-directory: ./renderers/lit
-        run: npm i
-
+        run: npm i && npm run build
       - name: Build Lit renderer
+        if: matrix.task == 'unit'
         working-directory: ./renderers/lit
-        run: npm run build
+        run: npm i && npm run build
+      - name: Run unit tests
+        if: matrix.task == 'unit'
+        working-directory: ./renderers/lit
+        run: npm run test:unit
 
-      - name: Run Lit renderer tests
+      # Integration tests take care of build:deps in the app under test
+      - name: Install Lit deps
+        if: matrix.task == 'integration'
+        working-directory: ./renderers/lit
+        run: npm i
+      - name: Run integration tests
+        if: matrix.task == 'integration'
         working-directory: ./renderers/lit
-        run: npm test
+        run: npm run test:integration

renderers/lit/a2ui_explorer/.gitignore

@@ -1,3 +1,4 @@
 node_modules
 dist
 public/specs
+src/generated/

renderers/lit/a2ui_explorer/karma.conf.cjs

@@ -0,0 +1,56 @@
+/**
+ * Copyright 2026 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+const path = require('path');
+
+module.exports = function (config) {
+  config.set({
+    basePath: '',
+    frameworks: ['jasmine'],
+    plugins: [require('karma-jasmine'), require('karma-chrome-launcher'), require('karma-esbuild')],
+    files: [{pattern: 'tests/**/*.test.ts', watched: true}],
+    preprocessors: {
+      'tests/**/*.test.ts': ['esbuild'],
+    },
+    esbuild: {
+      tsconfig: './tsconfig.json',
+      target: 'es2022',
+      format: 'iife',
+      sourcemap: true,
+      alias: {
+        // Map @a2ui/lit packages directly to their TypeScript source files.
+        // This allows tests to run against live code changes without requiring
+        // a rebuild step first.
+        '@a2ui/lit/v0_9': path.resolve(__dirname, '../src/v0_9/index.ts'),
+        '@a2ui/lit': path.resolve(__dirname, '../src/index.ts'),
+      },
+    },
+    reporters: ['progress'],
+    port: 9876,
+    colors: true,
+    logLevel: config.LOG_INFO,
+    autoWatch: false,
+    browsers: ['ChromeHeadless'],
+    singleRun: true,
+    concurrency: Infinity,
+    hostname: '127.0.0.1',
+    listenAddress: '127.0.0.1',
+    captureTimeout: 210000,
+    browserNoActivityTimeout: 210000,
+    browserDisconnectTimeout: 10000,
+    browserDisconnectTolerance: 3,
+  });
+};