test: add dual-major rspack compatibility smoke suite

.changeset/rspack-2-support.md

@@ -0,0 +1,11 @@
+---
+"@callstack/repack": minor
+---
+
+Add Rspack 2 support. Re.Pack now works with both Rspack 1.x and 2.x from a single release - it detects the installed `@rspack/core` major and adjusts its behavior automatically. Rspack 1 and webpack setups are unaffected: nothing changes unless you upgrade.
+
+To move a project to Rspack 2:
+
+- Use Node.js `^20.19.0 || >=22.12.0` - required by Rspack 2 itself; Re.Pack raises a clear error on older versions instead of failing with `ERR_REQUIRE_ESM`
+- Install `@rspack/plugin-react-refresh@^2` and `react-refresh` - under Rspack 2, development/HMR support is wired through the official React Refresh plugin
+- Move any `experiments.cache` configuration to the top-level `cache` option - Rspack 2 ignores the legacy location, and Re.Pack warns when it detects it

.github/workflows/test.yml

@@ -72,6 +72,24 @@ jobs:
       - name: Run tests against Rspack 1
         run: pnpm turbo run test:rspack1
 
+  test_pr_rspack_compat:
+    name: Tests [Rspack compat smoke]
+    if: github.event_name == 'pull_request'
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # tag=v4.2.2
+      - name: Setup workspace
+        uses: ./.github/actions/setup-pnpm-node
+        with:
+          node-version: '24'
+
+      # built-dist smoke tests: pack repack into a tarball, install it into
+      # standalone fixtures pinning each @rspack/core major, and assert the
+      # dual-major behavior matrix against the real dist
+      - name: Run dual-major smoke suite
+        run: pnpm --filter rspack-compat-test test:smoke
+
   test_pr_windows:
     name: Tests [Windows]
     if: github.event_name == 'pull_request'

AGENTS.md

@@ -31,3 +31,4 @@ Re.Pack is a toolkit for building and developing React Native applications with
 - `tests/integration/`: Integration-level automated coverage.
 - `tests/metro-compat/`: Metro compatibility behavior coverage.
 - `tests/resolver-cases/`: Resolver behavior and edge-case coverage.
+- `tests/rspack-compat/`: Built-dist smoke coverage across both supported `@rspack/core` majors (standalone, tarball-installed fixtures).

tests/rspack-compat/.gitignore

@@ -0,0 +1,7 @@
+# per-run artifacts - the fixtures are standalone projects that get a fresh
+# repack tarball installed on every run
+.pack/
+fixtures/*/node_modules/
+fixtures/*/pnpm-lock.yaml
+fixtures/*/callstack-repack.tgz
+fixtures/*/dist/

tests/rspack-compat/README.md

@@ -0,0 +1,73 @@
+# rspack-compat
+
+Built-dist smoke tests for `@callstack/repack` against both supported
+`@rspack/core` majors (1.x and 2.x).
+
+Unit tests exercise sources through the Jest/Babel pipeline; the failure
+modes this suite covers — `require(esm)` interop, loader resolution, React
+Refresh runtime source selection — only reproduce against the **built dist**
+installed in a real project layout. The runner therefore always builds
+`packages/repack`, packs it into a tarball, installs the tarball into each
+fixture, and runs the assertions there.
+
+## Running
+
+```sh
+pnpm --filter rspack-compat-test test:smoke      # both fixtures
+pnpm --filter rspack-compat-test test:smoke rspack-2   # a single fixture
+```
+
+The suite performs network installs and full repack builds, so it is
+deliberately **not** part of the default `test` pipeline — CI runs it in a
+dedicated lane.
+
+## What is asserted (per major)
+
+1. `getRepackConfig` routing — `experiments.parallelLoader` kept under
+   Rspack 1 / dropped under Rspack 2; `exportsPresence: 'auto'` parser
+   override under Rspack 2 only.
+2. Legacy `experiments.cache` handling, composed with the `isRspack2` gate
+   the commands use — the gate reads the fixture's installed major, Rspack 1
+   sees no warning, Rspack 2 warns exactly once under the warn-only policy,
+   the config is never mutated, and the cache accessor reads the legacy
+   location.
+3. `ensureNodeSupportsRspack` passes on a supported Node version.
+4. The compiled command modules (`dist/commands/rspack/{bundle,start,Compiler}.js`)
+   load from the tarball-installed package — the eager
+   `require('@rspack/core')` they compile to (`require(esm)` under
+   Rspack 2), the `rspack` named export they call, and the lazy
+   `@callstack/repack/commands/rspack` entry.
+5. A full dev build through `DevelopmentPlugin` — HMR client and React
+   Refresh wiring present in the bundle, with the refresh runtime coming
+   from the correct source per major: the vendored client files
+   (`packages/repack/vendor/react-refresh/`) under Rspack 1 with zero
+   official-plugin references, the official `@rspack/plugin-react-refresh`
+   under Rspack 2 with zero vendored references.
+
+## Why the fixtures are standalone (tarball install)
+
+Inside the pnpm workspace, repack is linked as a symlink, so its own
+`@rspack/core@^2` devDependency shadows any fixture's v1 pin — bare
+`import '@rspack/core'` from `packages/repack/dist` resolves repack's copy
+before the project's. An in-workspace v1 fixture would therefore silently
+test v2 twice. Published installs don't have this problem (`@rspack/core`
+is a peer dependency there), and shipped code deliberately carries no
+monorepo-aware resolution workarounds, so the fixtures replicate the
+published layout instead: each one is its own pnpm workspace root
+(`pnpm-workspace.yaml` with `packages: []`) with its own `node_modules`,
+installing repack from a packed tarball — the same pattern as
+`apps/tester-app-rspack1`.
+
+`smoke.cjs` enforces this as a **lane guard** before running any behavior
+assertions: the fixture's installed `@rspack/core` major must match the
+major declared in its manifest, the `@rspack/core` that *repack itself*
+resolves must be that same copy, and the resolved repack package must live
+inside the fixture's `node_modules` (never a workspace link back to
+`packages/repack`). Any violation aborts the run with a non-zero exit.
+
+`react-native` is stubbed (`fixtures/shared/rn-stub`) with just the modules
+Re.Pack's development runtime imports — real RN sources need the full
+flow/babel loader chain, which is out of scope for wiring-level smoke tests.
+
+See `agent_context/rspackv2-jul2026/design.md` for the overall dual-major
+support design.

tests/rspack-compat/fixtures/rspack-1/package.json

@@ -0,0 +1,11 @@
+{
+  "name": "rspack-compat-fixture-rspack-1",
+  "version": "0.0.1",
+  "description": "Rspack 1 smoke fixture - installs @callstack/repack from a packed tarball like a real user project",
+  "private": true,
+  "devDependencies": {
+    "@callstack/repack": "file:./callstack-repack.tgz",
+    "@rspack/core": "^1.7.12",
+    "react-native": "file:../shared/rn-stub"
+  }
+}

tests/rspack-compat/fixtures/rspack-1/pnpm-workspace.yaml

@@ -0,0 +1,4 @@
+# Marks this directory as its own workspace root, so pnpm treats it as a
+# standalone project instead of a member of the repository workspace.
+# See ../../README.md for why the fixtures must stay outside the workspace.
+packages: []

tests/rspack-compat/fixtures/rspack-1/src/App.jsx

@@ -0,0 +1,3 @@
+export function App() {
+  return null;
+}

tests/rspack-compat/fixtures/rspack-2/package.json

@@ -0,0 +1,14 @@
+{
+  "name": "rspack-compat-fixture-rspack-2",
+  "version": "0.0.1",
+  "description": "Rspack 2 smoke fixture - installs @callstack/repack from a packed tarball like a real user project",
+  "private": true,
+  "devDependencies": {
+    "@callstack/repack": "file:./callstack-repack.tgz",
+    "@rspack/core": "^2.1.2",
+    "@rspack/plugin-react-refresh": "^2.0.2",
+    "@swc/helpers": "^0.5.23",
+    "react-native": "file:../shared/rn-stub",
+    "react-refresh": "^0.18.0"
+  }
+}

tests/rspack-compat/fixtures/rspack-2/pnpm-workspace.yaml

@@ -0,0 +1,4 @@
+# Marks this directory as its own workspace root, so pnpm treats it as a
+# standalone project instead of a member of the repository workspace.
+# See ../../README.md for why the fixtures must stay outside the workspace.
+packages: []

tests/rspack-compat/fixtures/rspack-2/src/App.jsx

@@ -0,0 +1,3 @@
+export function App() {
+  return null;
+}

tests/rspack-compat/fixtures/shared/rn-stub/Libraries/Core/NativeExceptionsManager.js

@@ -0,0 +1,6 @@
+export default {
+  hide() {},
+  showMessage() {},
+  dismissRedbox() {},
+  reportException() {},
+};

tests/rspack-compat/fixtures/shared/rn-stub/Libraries/NativeModules/specs/NativeRedBox.js

@@ -0,0 +1,6 @@
+export default {
+  hide() {},
+  showMessage() {},
+  dismissRedbox() {},
+  reportException() {},
+};

tests/rspack-compat/fixtures/shared/rn-stub/Libraries/Utilities/DevLoadingView.js

@@ -0,0 +1,6 @@
+export default {
+  hide() {},
+  showMessage() {},
+  dismissRedbox() {},
+  reportException() {},
+};

tests/rspack-compat/fixtures/shared/rn-stub/index.js

@@ -0,0 +1,2 @@
+export const DevSettings = { reload() {} };
+export const LogBox = { clearAllLogs() {} };

tests/rspack-compat/fixtures/shared/rn-stub/package.json

@@ -0,0 +1,7 @@
+{
+  "name": "react-native",
+  "version": "0.84.1",
+  "description": "Stub of react-native for the rspack-compat smoke fixtures - covers the modules imported by Re.Pack's development runtime (real RN sources need the full flow/babel loader chain, which is out of scope for wiring-level smoke tests)",
+  "private": true,
+  "main": "index.js"
+}

tests/rspack-compat/package.json

@@ -0,0 +1,13 @@
+{
+  "name": "rspack-compat-test",
+  "version": "0.0.1",
+  "description": "Built-dist smoke tests for @callstack/repack against both @rspack/core majors",
+  "private": true,
+  "type": "module",
+  "engines": {
+    "node": ">=22"
+  },
+  "scripts": {
+    "test:smoke": "node run.mjs"
+  }
+}

tests/rspack-compat/run.mjs

@@ -0,0 +1,101 @@
+// Drives the dual-major smoke fixtures: builds @callstack/repack, packs it
+// into a tarball, installs that tarball into each standalone fixture and
+// runs smoke.cjs against the result.
+//
+// Usage: node run.mjs [fixture...]   (default: all fixtures)
+import { execFileSync } from 'node:child_process';
+import fs from 'node:fs';
+import path from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+const suiteDir = path.dirname(fileURLToPath(import.meta.url));
+const repoRoot = path.resolve(suiteDir, '../..');
+const repackDir = path.join(repoRoot, 'packages/repack');
+const packDir = path.join(suiteDir, '.pack');
+
+const allFixtures = ['rspack-1', 'rspack-2'];
+const requested = process.argv.slice(2);
+const fixtures = requested.length > 0 ? requested : allFixtures;
+
+for (const fixture of fixtures) {
+  if (!allFixtures.includes(fixture)) {
+    console.error(
+      `Unknown fixture '${fixture}' - expected one of: ${allFixtures.join(', ')}`
+    );
+    process.exit(1);
+  }
+}
+
+function run(command, args, options = {}) {
+  console.log(`\n$ ${command} ${args.join(' ')}`);
+  execFileSync(command, args, { stdio: 'inherit', ...options });
+}
+
+// The lane guard in smoke.cjs verifies the *installed* major against the
+// fixture's declared intent - derive that intent from the fixture manifest
+// so the two can never drift apart silently.
+function expectedMajorOf(fixtureDir) {
+  const manifest = JSON.parse(
+    fs.readFileSync(path.join(fixtureDir, 'package.json'), 'utf8')
+  );
+  const range = manifest.devDependencies['@rspack/core'];
+  const major = Number.parseInt(range.replace(/^\D*/, ''), 10);
+  if (!Number.isInteger(major)) {
+    throw new Error(
+      `Cannot derive the expected @rspack/core major from range '${range}'`
+    );
+  }
+  return major;
+}
+
+// 1. Build and pack repack. The suite exists to test the *built dist* - the
+// failure modes it covers (require(esm) interop, loader resolution, refresh
+// runtime source selection) don't reproduce through the Jest/Babel pipeline,
+// so it must never run against stale sources. Built through turbo so that
+// workspace dependencies (repack-dev-server) are built first.
+run('pnpm', ['turbo', 'run', 'build', '--filter', '@callstack/repack'], {
+  cwd: repoRoot,
+});
+fs.rmSync(packDir, { recursive: true, force: true });
+fs.mkdirSync(packDir, { recursive: true });
+run('pnpm', ['pack', '--pack-destination', packDir], { cwd: repackDir });
+
+const tarball = fs.readdirSync(packDir).find((file) => file.endsWith('.tgz'));
+if (!tarball) {
+  throw new Error('pnpm pack produced no tarball');
+}
+
+// 2. Install the tarball into each fixture and run the assertions.
+const failed = [];
+
+for (const fixture of fixtures) {
+  const fixtureDir = path.join(suiteDir, 'fixtures', fixture);
+  console.log(`\n=== fixture: ${fixture} ===`);
+
+  fs.copyFileSync(
+    path.join(packDir, tarball),
+    path.join(fixtureDir, 'callstack-repack.tgz')
+  );
+
+  try {
+    run('pnpm', ['install', '--no-frozen-lockfile'], { cwd: fixtureDir });
+    run('node', [path.join(suiteDir, 'smoke.cjs')], {
+      cwd: fixtureDir,
+      env: {
+        ...process.env,
+        RSPACK_COMPAT_EXPECTED_MAJOR: String(expectedMajorOf(fixtureDir)),
+      },
+    });
+    console.log(`=== fixture ${fixture}: PASS ===`);
+  } catch {
+    failed.push(fixture);
+    console.error(`=== fixture ${fixture}: FAIL ===`);
+  }
+}
+
+if (failed.length > 0) {
+  console.error(`\nSmoke suite failed for: ${failed.join(', ')}`);
+  process.exit(1);
+}
+
+console.log(`\nSmoke suite passed for: ${fixtures.join(', ')}`);