Make it so that we can console.log in browser to debug gentest (#1718)

Summary:
Pull Request resolved: https://github.com/facebook/yoga/pull/1718

Our gentest works by console.logging the contents of the test it is generating to the browser powered by the driver. The driver then reads the logs and writes it to a file. An unfortunate side effect here is that we cannot console.log to debug how the gentest logic actually works since the driver is expecting formatted code. To get around this I had the driver filter out logs with a certain prefix and add that a helper that logs a message with this prefix to the scripts.

Reviewed By: NickGerleman

Differential Revision: D64011035

fbshipit-source-id: 1f113fde425d1d7db1c16ab85f4bb16b0e18f41d

gentest/gentest-driver.ts

@@ -100,15 +100,21 @@ for (const fileName of fixtures) {
   await driver.get('file://' + process.cwd() + '/test.html');
   const logs = await driver.manage().logs().get(logging.Type.BROWSER);
 
+  const testLogs = logs.filter(
+    log => !log.message.replace(/^[^"]*/, '').startsWith('"gentest-log:'),
+  );
+
   await fs.writeFile(
     `${yogaDir}/tests/generated/${fileNameNoExtension}.cpp`,
-    addSignatureToSourceCode(JSON.parse(logs[0].message.replace(/^[^"]*/, ''))),
+    addSignatureToSourceCode(
+      JSON.parse(testLogs[0].message.replace(/^[^"]*/, '')),
+    ),
   );
 
   await fs.writeFile(
     `${yogaDir}/java/tests/generated/com/facebook/yoga/${fileNameNoExtension}.java`,
     addSignatureToSourceCode(
-      JSON.parse(logs[1].message.replace(/^[^"]*/, '')).replace(
+      JSON.parse(testLogs[1].message.replace(/^[^"]*/, '')).replace(
         'YogaTest',
         fileNameNoExtension,
       ),
@@ -118,7 +124,7 @@ for (const fileName of fixtures) {
   await fs.writeFile(
     `${yogaDir}/javascript/tests/generated/${fileNameNoExtension}.test.ts`,
     addSignatureToSourceCode(
-      JSON.parse(logs[2].message.replace(/^[^"]*/, '')).replace(
+      JSON.parse(testLogs[2].message.replace(/^[^"]*/, '')).replace(
         'YogaTest',
         fileNameNoExtension,
       ),

gentest/gentest-log.js

@@ -0,0 +1,11 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+// eslint-disable-next-line no-unused-vars
+function gentestLog(message) {
+  console.log('gentest-log: ', message);
+}

gentest/test-template.html

@@ -8,6 +8,7 @@
   <script src="gentest-cpp.js"></script>
   <script src="gentest-java.js"></script>
   <script src="gentest-javascript.js"></script>
+  <script src="gentest-log.js"></script>
 
   <style>
     @font-face {