feat(testrunner): cache transformed files (#3451)

This makes parsing faster to the point where it is not worth it to report when files are parsed.

test/runner/fixturesUI.js

@@ -16,8 +16,7 @@
 
 const { FixturePool, registerFixture, registerWorkerFixture } = require('./fixturePool');
 const { Test, Suite } = require('mocha');
-const pirates = require('pirates');
-const babel = require('@babel/core');
+const {installTransform} = require('./transform');
 const commonSuite = require('mocha/lib/interfaces/common');
 
 Error.stackTraceLimit = 15;
@@ -135,16 +134,7 @@ function fixturesUI(trialRun, suite) {
     context.fit = it.only(true);
     context.xit = it.skip(true);
 
-    revertBabelRequire = pirates.addHook((code, filename) => {
-      const result = babel.transformFileSync(filename, {
-        presets: [
-          ['@babel/preset-env', {targets: {node: 'current'}}],
-          '@babel/preset-typescript']
-      });
-      return result.code;
-    }, {
-      exts: ['.ts']
-    });
+    revertBabelRequire = installTransform();
   });
 
   suite.on(Suite.constants.EVENT_FILE_POST_REQUIRE, function(context, file, mocha) {

test/runner/index.js

@@ -39,10 +39,6 @@ program
     const files = collectFiles(path.join(process.cwd(), command.args[0]), command.args.slice(1));
     const rootSuite = new Mocha.Suite('', new Mocha.Context(), true);
 
-    if (!command.reporter) {
-      // TODO: extend reporter interface.
-      console.log(`Parsing ${files.length} test files`);
-    }
     let total = 0;
     // Build the test model, suite per file.
     for (const file of files) {
@@ -59,11 +55,6 @@ program
       let runner;
       await new Promise(f => {
         runner = mocha.run(f);
-        if (!command.reporter) {
-          runner.on(constants.EVENT_RUN_BEGIN, () => {
-            process.stdout.write(colors.yellow('\u00B7'));
-          });
-        }
       });
       total += runner.grepTotal(mocha.suite);
 

test/runner/transform.js

@@ -0,0 +1,60 @@
+/**
+ * Copyright (c) Microsoft Corporation.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+const crypto = require('crypto');
+const os = require('os');
+const path = require('path');
+const fs = require('fs');
+const pirates = require('pirates');
+const babel = require('@babel/core');
+const version = 0;
+const cacheDir = path.join(os.tmpdir(), 'playwright-transform-cache');
+
+/**
+ * @param {string} content 
+ * @param {string} filePath 
+ * @return {string}
+ */
+function calculateCachePath(content, filePath) {
+  const hash = crypto.createHash('sha1').update(content).update(filePath).update(String(version)).digest('hex');
+  const fileName = path.basename(filePath, path.extname(filePath)).replace(/\W/g, '') + '_' + hash;
+
+  return path.join(cacheDir, hash[0] + hash[1], fileName);
+}
+
+function installTransform() {
+  return pirates.addHook((code, filename) => {
+    const cachePath = calculateCachePath(code, filename);
+    const codePath = cachePath + '.js';
+    if (fs.existsSync(codePath))
+      return fs.readFileSync(codePath, 'utf8');
+    
+    const result = babel.transformFileSync(filename, {
+      presets: [
+        ['@babel/preset-env', {targets: {node: 'current'}}],
+        '@babel/preset-typescript'],
+    });
+    if (result.code) {
+      fs.mkdirSync(path.dirname(cachePath), {recursive: true});
+      fs.writeFileSync(codePath, result.code, 'utf8');
+    }
+    // TODO(einbinder) sourcemaps
+    return result.code;
+  }, {
+    exts: ['.ts']
+  });
+}
+
+module.exports = {installTransform};