test(integration): begin moving from Karma to Web Test Runner

.github/workflows/web-test-runner.yml

@@ -0,0 +1,67 @@
+name: Run Web Test Runner integration tests
+
+on:
+    push:
+        branches:
+            - master
+            - release
+            - 'spring*'
+            - 'summer*'
+            - 'winter*'
+    pull_request:
+        branches:
+            - master
+            - release
+            - 'spring*'
+            - 'summer*'
+            - 'winter*'
+
+env:
+    SAUCE_USERNAME: ${{secrets.SAUCE_USERNAME}}
+    SAUCE_ACCESS_KEY: ${{secrets.SAUCE_ACCESS_KEY}}
+    GITHUB_RUN_ID: ${{github.run_id}}
+    COVERAGE: '1'
+    NODE_VERSION: '20.18.1'
+
+jobs:
+    # Starting with the basics, just get tests running in CI
+    # TODO: add env var combos we use for Karma tests
+    # TODO: upload result artifacts
+    # TODO: make it saucy 🥫
+    run-wtr-tests-group-1:
+        runs-on: ubuntu-22.04
+        env:
+            SAUCE_TUNNEL_ID: github-action-tunnel-wtr-${{github.run_id}}-group-1
+        defaults:
+            run:
+                working-directory: ./packages/@lwc/integration-not-karma
+        steps:
+            - name: Checkout repository
+              uses: actions/checkout@v4
+
+            - name: Setup Node
+              uses: actions/setup-node@v4
+              with:
+                  node-version: ${{ env.NODE_VERSION }}
+                  cache: 'yarn'
+
+            - name: Install dependencies
+              run: yarn install --frozen-lockfile
+              working-directory: ./
+
+            # - uses: saucelabs/sauce-connect-action@v3.0.0
+            #   with:
+            #       username: ${{ secrets.SAUCE_USERNAME }}
+            #       accessKey: ${{ secrets.SAUCE_ACCESS_KEY }}
+            #       tunnelName: ${{ env.SAUCE_TUNNEL_ID }}
+            #       region: us
+
+            - run: yarn test
+
+    run-karma-tests:
+        runs-on: ubuntu-22.04
+        defaults:
+            run:
+                working-directory: ./packages/@lwc/integration-not-karma
+        needs:
+            - run-wtr-tests-group-1

eslint.config.mjs

@@ -218,7 +218,7 @@ export default tseslint.config(
         },
     },
     {
-        files: ['packages/@lwc/integration-karma/**'],
+        files: ['packages/@lwc/integration-karma/**', 'packages/@lwc/integration-not-karma/**'],
 
         languageOptions: {
             globals: {
@@ -355,7 +355,7 @@ export default tseslint.config(
         },
     },
     {
-        files: ['packages/@lwc/integration-karma/**'],
+        files: ['packages/@lwc/integration-karma/**', 'packages/@lwc/integration-not-karma/**'],
 
         languageOptions: {
             globals: {

packages/@lwc/integration-not-karma/LICENSE.md

@@ -0,0 +1,108 @@
+# LWC core license
+
+MIT LICENSE
+
+Copyright (c) 2025, Salesforce, Inc.
+All rights reserved.
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+# Licenses of bundled dependencies
+
+## @parse5/tools
+
+The MIT License (MIT)
+
+Copyright © 2024 James Garbutt
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the “Software”), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
+
+## entities
+
+Copyright (c) Felix Böhm
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
+
+Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
+
+Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
+
+THIS IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS,
+EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+## estree-walker
+
+Copyright (c) 2015-20 [these people](https://github.com/Rich-Harris/estree-walker/graphs/contributors)
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+## observable-membrane
+
+MIT License
+
+Copyright (c) 2017 Salesforce
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+
+## parse5
+
+Copyright (c) 2013-2019 Ivan Nikulin (ifaaan@gmail.com, https://github.com/inikulin)
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.

packages/@lwc/integration-not-karma/README.md

@@ -0,0 +1,3 @@
+# @lwc/integration-not-karma
+
+It's not karma, it's something else!

packages/@lwc/integration-not-karma/helpers/lwc.mjs

@@ -0,0 +1,97 @@
+import path from 'node:path';
+import { rollup } from 'rollup';
+import lwcRollupPlugin from '@lwc/rollup-plugin';
+
+import {
+    DISABLE_SYNTHETIC_SHADOW_SUPPORT_IN_COMPILER,
+    API_VERSION,
+    DISABLE_STATIC_CONTENT_OPTIMIZATION,
+} from './options.mjs';
+
+// Cache reused between each compilation to speed up the compilation time.
+let cache;
+
+export default async (ctx) => {
+    const input = ctx.path.slice(1); // strip leading / from URL path to get relative file path
+    const suiteDir = path.dirname(input);
+
+    // TODO [#3370]: remove experimental template expression flag
+    const experimentalComplexExpressions = suiteDir.includes('template-expressions');
+
+    const createRollupPlugin = (options) => {
+        return lwcRollupPlugin({
+            // Sourcemaps don't work with Istanbul coverage
+            sourcemap: !process.env.COVERAGE,
+            experimentalDynamicComponent: {
+                loader: 'test-utils',
+                strict: true,
+            },
+            enableDynamicComponents: true,
+            enableLwcOn: true,
+            experimentalComplexExpressions,
+            enableStaticContentOptimization: !DISABLE_STATIC_CONTENT_OPTIMIZATION,
+            disableSyntheticShadowSupport: DISABLE_SYNTHETIC_SHADOW_SUPPORT_IN_COMPILER,
+            apiVersion: API_VERSION,
+            modules: [
+                {
+                    // Assume `ctx.path` is a component file, e.g. modules/x/foo/foo.js
+                    dir: path.resolve(input, '../../..'),
+                },
+            ],
+            ...options,
+        });
+    };
+
+    const defaultRollupPlugin = createRollupPlugin();
+
+    const customLwcRollupPlugin = {
+        ...defaultRollupPlugin,
+        transform(src, id) {
+            let rollupPluginToUse;
+
+            // Override the LWC Rollup plugin to specify different options based on file name patterns.
+            // This allows us to alter the API version or other compiler props on a filename-only basis.
+            const apiVersion = id.match(/useApiVersion(\d+)/)?.[1];
+            const nativeOnly = /\.native-only\./.test(id);
+            if (apiVersion) {
+                rollupPluginToUse = createRollupPlugin({
+                    apiVersion: parseInt(apiVersion, 10),
+                });
+            } else if (nativeOnly) {
+                rollupPluginToUse = createRollupPlugin({ disableSyntheticShadowSupport: true });
+            } else {
+                rollupPluginToUse = defaultRollupPlugin;
+            }
+            return rollupPluginToUse.transform.call(this, src, id);
+        },
+    };
+
+    const bundle = await rollup({
+        input,
+        cache,
+        plugins: [customLwcRollupPlugin],
+
+        // Rollup should not attempt to resolve the engine and the test utils, Karma takes care of injecting it
+        // globally in the page before running the tests.
+        external: ['lwc', 'wire-service', 'test-utils', '@test/loader'],
+
+        onwarn(warning, warn) {
+            // Ignore warnings from our own Rollup plugin
+            if (warning.plugin !== 'rollup-plugin-lwc-compiler') {
+                warn(warning);
+            }
+        },
+    });
+
+    cache = bundle.cache;
+
+    const { output } = await bundle.generate({
+        format: 'esm',
+        // TODO: Does web-test-runner use istanbul?
+        // Sourcemaps don't work with Istanbul coverage
+        sourcemap: process.env.COVERAGE ? false : 'inline',
+    });
+
+    const { code } = output[0];
+    return code;
+};