Convert source to Buffer when getting asset's hash

package.json

@@ -105,6 +105,7 @@
     "sinon": "^6.3.4",
     "tempy": "^0.2.1",
     "url-search-params": "^1.1.0",
-    "webpack": "^4.19.1"
+    "webpack": "^4.19.1",
+    "worker-plugin": "^3.1.0"
   }
 }

packages/workbox-webpack-plugin/src/lib/get-asset-hash.js

@@ -16,6 +16,6 @@ const crypto = require('crypto');
  */
 module.exports = (asset) => {
   return crypto.createHash('md5')
-      .update(asset.source(), 'utf8')
+      .update(Buffer.from(asset.source()))
       .digest('hex');
 };

test/workbox-webpack-plugin/node/generate-sw.js

@@ -8,6 +8,7 @@
 
 const CopyWebpackPlugin = require('copy-webpack-plugin');
 const HtmlWebpackPlugin = require('html-webpack-plugin');
+const WorkerPlugin = require('worker-plugin');
 const expect = require('chai').expect;
 const fse = require('fs-extra');
 const glob = require('glob');
@@ -1646,4 +1647,51 @@ describe(`[workbox-webpack-plugin] GenerateSW (End to End)`, function() {
       });
     });
   });
+
+  describe(`[workbox-webpack-plugin] WASM Code`, function() {
+    // See https://github.com/GoogleChrome/workbox/issues/1916
+    it(`should support projects that bundle WASM code`, function(done) {
+      const indexFilename = 'index.js';
+      const outputDir = tempy.directory();
+      const srcDir = path.join(__dirname, '..', 'static', 'wasm-project');
+      const config = {
+        mode: 'production',
+        entry: {
+          index: path.join(srcDir, indexFilename),
+        },
+        output: {
+          filename: '[name].js',
+          globalObject: 'self',
+          path: outputDir,
+        },
+        plugins: [
+          new WorkerPlugin(),
+          new GenerateSW(),
+        ],
+      };
+
+      const compiler = webpack(config);
+      compiler.run(async (webpackError, stats) => {
+        if (webpackError) {
+          return done(webpackError);
+        }
+
+        try {
+          const statsJson = stats.toJson('verbose');
+          expect(statsJson.warnings).to.have.lengthOf(0);
+
+          // Bundling WASM into a Worker seems to lead to different hashes in
+          // different environments. Instead of hardcoding hash checks, just
+          // confirm that we output the expected number of files, which will
+          // only be true if the build was successful.
+          const files = glob.sync(`${outputDir}/*`);
+          expect(files).to.have.length(6);
+
+          done();
+        } catch (error) {
+          done(error);
+        }
+      });
+    });
+  });
 });

test/workbox-webpack-plugin/static/wasm-project/index.js

@@ -0,0 +1,9 @@
+/*
+  Copyright 2018 Google LLC
+
+  Use of this source code is governed by an MIT-style
+  license that can be found in the LICENSE file or at
+  https://opensource.org/licenses/MIT.
+*/
+
+new Worker('./worker.js', {type: 'module'});

test/workbox-webpack-plugin/static/wasm-project/worker.js

@@ -0,0 +1,11 @@
+/*
+  Copyright 2018 Google LLC
+
+  Use of this source code is governed by an MIT-style
+  license that can be found in the LICENSE file or at
+  https://opensource.org/licenses/MIT.
+*/
+
+import('./add.wasm').then(({add}) => {
+  return add(10, 20);
+});