refactor: make test code conditional via ENABLE_TESTS env var

Test code in background.ts and test-content-script.js now only builds
when ENABLE_TESTS=true is set. Production builds (default) exclude test
code completely via esbuild's define feature.

Changes:
- esbuild.config.js: conditionally add test entrypoints and define ENABLE_TESTS
- background.ts: wrap test message listener in if (ENABLE_TESTS) block
- Dockerfile: add test_builder stage that builds with ENABLE_TESTS=true
- package-lock.json: updated from npm install

Verified with typecheck and lint.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Dockerfile

@@ -20,12 +20,32 @@ RUN npm install
 # Copy source code (respecting .dockerignore)
 COPY . .
 
-# Build the extension for Firefox (default)
+# Build the extension for Firefox (default) - without tests
 RUN npm run build
 
 # Create the package
 RUN npm run create-package
 
+# Test builder stage - builds with ENABLE_TESTS=true
+FROM node:lts AS test_builder
+
+WORKDIR /app
+
+# Copy package files for dependency installation
+COPY package.json package-lock.json ./
+
+# Install dependencies
+RUN npm install
+
+# Copy source code
+COPY . .
+
+# Build with tests enabled
+RUN ENABLE_TESTS=true npm run build
+
+# Create the package
+RUN npm run create-package
+
 # Code quality stage - for running quality checks
 FROM builder AS code_quality
 RUN npm run typecheck && npm run lint
@@ -47,8 +67,8 @@ FROM node:lts AS runtime
 
 WORKDIR /app
 
-# Copy built extension from builder
-COPY --from=builder /app /app
+# Copy built extension from test_builder (includes test code)
+COPY --from=test_builder /app /app
 
 # Install Firefox and Xvfb for headless execution (cached layer)
 RUN apt-get update && apt-get install -y \

background.ts

@@ -2,11 +2,13 @@ import { init } from "./memory";
 
 // Use global browser object directly (available in extension context)
 declare const browser: any;
+declare const ENABLE_TESTS: boolean;
 
 init();
 
 // Test verification handler for Marionette tests
 // This proves the background script is executing and can communicate with content scripts
+if (ENABLE_TESTS) {
     browser.runtime.onMessage.addListener((message: any, sender: any, sendResponse: any) => {
         if (message.type === 'RENTGEN_TEST_VERIFICATION') {
             // Perform a computation to prove the background script is running
@@ -28,3 +30,4 @@ browser.runtime.onMessage.addListener((message: any, sender: any, sendResponse:
             return true;  // Keep channel open for async response
         }
     });
+}

esbuild.config.js

@@ -8,6 +8,8 @@ const watch = process.argv.includes('--watch') && {
     },
 };
 
+const ENABLE_TESTS = process.env.ENABLE_TESTS === 'true';
+
 // see https://github.com/evanw/esbuild/issues/806#issuecomment-779138268
 let skipReactImports = {
     name: 'skipReactImports',
@@ -41,18 +43,23 @@ let skipReactImports = {
     },
 };
 
-esbuild
-    .build({
-        entryPoints: [
+const entryPoints = [
     'components/toolbar/toolbar.tsx',
     'components/sidebar/sidebar.tsx',
     'components/report-window/report-window.tsx',
     'background.ts',
-            'tests/test-content-script.js',
     'diag.tsx',
     'styles/global.scss',
     'styles/fonts.scss',
-        ],
+];
+
+if (ENABLE_TESTS) {
+    entryPoints.push('tests/test-content-script.js');
+}
+
+esbuild
+    .build({
+        entryPoints,
         bundle: true,
         // minify: true,
         outdir: './lib',
@@ -61,6 +68,7 @@ esbuild
         define: {
             PLUGIN_NAME: '"Rentgen"',
             PLUGIN_URL: '"https://addons.mozilla.org/pl/firefox/addon/rentgen/"',
+            ENABLE_TESTS: String(ENABLE_TESTS),
         },
         external: ['react', 'react-dom', 'survey-react'],
         watch,