Change worker chunk name from <ID> to w<ID>

Fixes GoogleChromeLabs#43, as it avoids conflicts with other number-based webpack
chunks.
Note that the conflict may not be on the filename (since this plugin
adds '.worker' to it) but on the internal key used by webpack in
referencing modules.

src/index.js

@@ -67,7 +67,7 @@ export default class WorkerPlugin {
               return false;
             }
 
-            const loaderOptions = { name: opts.name || workerId + '' };
+            const loaderOptions = { name: opts.name || 'w' + workerId };
             const req = `require(${JSON.stringify(workerLoader + '?' + JSON.stringify(loaderOptions) + '!' + dep.string)})`;
             const id = `__webpack__worker__${workerId++}`;
             ParserHelpers.toConstantDependency(parser, id)(expr.arguments[0]);

test/index.test.js

@@ -38,7 +38,7 @@ describe('worker-plugin', () => {
 
     const assetNames = Object.keys(stats.assets);
     expect(assetNames).toHaveLength(2);
-    expect(assetNames).toContainEqual('0.worker.js');
+    expect(assetNames).toContainEqual('w0.worker.js');
 
     const main = stats.assets['main.js'];
     expect(main).toMatch(/[^\n]*new\s+Worker\s*\([^)]*\)[^\n]*/g);
@@ -56,7 +56,7 @@ describe('worker-plugin', () => {
       /new\s+Worker\s*\(\s*__webpack__worker__\d\s*(,\s*\{\s+type\:\svoid [0]\s+\}\s*)?\)/g
     );
 
-    expect(main).toMatch(/module.exports = __webpack_require__\.p\s*\+\s*"0\.worker\.js"/g);
+    expect(main).toMatch(/module.exports = __webpack_require__\.p\s*\+\s*"w0\.worker\.js"/g);
   });
 
   test('it replaces multiple Worker exports with __webpack_require__', async () => {
@@ -68,12 +68,12 @@ describe('worker-plugin', () => {
 
     const assetNames = Object.keys(stats.assets);
     expect(assetNames).toHaveLength(3);
-    expect(assetNames).toContainEqual('0.worker.js');
-    expect(assetNames).toContainEqual('1.worker.js');
+    expect(assetNames).toContainEqual('w0.worker.js');
+    expect(assetNames).toContainEqual('w1.worker.js');
 
     const main = stats.assets['main.js'];
-    expect(main).toMatch(/module.exports = __webpack_require__\.p\s*\+\s*"0\.worker\.js"/g);
-    expect(main).toMatch(/module.exports = __webpack_require__\.p\s*\+\s*"1\.worker\.js"/g);
+    expect(main).toMatch(/module.exports = __webpack_require__\.p\s*\+\s*"w0\.worker\.js"/g);
+    expect(main).toMatch(/module.exports = __webpack_require__\.p\s*\+\s*"w1\.worker\.js"/g);
   });
 
   test('retainModule:true leaves {type:module} in worker init', async () => {
@@ -248,8 +248,8 @@ describe('worker-plugin', () => {
           await sleep(1000);
           stats = await ready;
           await sleep(1000);
-          expect(Object.keys(stats.assets).sort()).toEqual(['0.worker.js', 'main.js']);
-          expect(stats.assets['0.worker.js']).toContain(`hello from worker ${i}`);
+          expect(Object.keys(stats.assets).sort()).toEqual(['main.js', 'w0.worker.js']);
+          expect(stats.assets['w0.worker.js']).toContain(`hello from worker ${i}`);
         }
       } finally {
         watcher.close();