switch jest to hermes

Author: kassens

package.json

@@ -67,6 +67,7 @@
     "google-closure-compiler": "^20200517.0.0",
     "gzip-size": "^5.1.1",
     "hermes-eslint": "^0.9.0",
+    "hermes-parser": "^0.9.0",
     "jasmine-check": "^1.0.0-rc.0",
     "jest": "^26.6.3",
     "jest-cli": "^26.6.3",

scripts/babel/transform-test-gate-pragma.js

@@ -278,7 +278,7 @@ function transform(babel) {
                 callee.name === 'it' ||
                 callee.name === 'fit'
               ) {
-                const comments = statement.leadingComments;
+                const comments = getComments(path);
                 if (comments !== undefined) {
                   const condition = buildGateCondition(comments);
                   if (condition !== null) {
@@ -304,7 +304,7 @@ function transform(babel) {
                 callee.property.type === 'Identifier' &&
                 callee.property.name === 'only'
               ) {
-                const comments = statement.leadingComments;
+                const comments = getComments(path);
                 if (comments !== undefined) {
                   const condition = buildGateCondition(comments);
                   if (condition !== null) {
@@ -331,4 +331,26 @@ function transform(babel) {
   };
 }
 
+function getComments(path) {
+  if (path.node.leadingComments) {
+    // Babel AST includes comments.
+    return path.node.leadingComments;
+  }
+  // In Hermes AST we need to find the comments by range.
+  const comments = path.hub.file.ast.comments;
+  let prevSibling = path.getPrevSibling();
+  let searchStart;
+  if (prevSibling.node) {
+    searchStart = prevSibling.node.end;
+  } else if (path.parentPath.node) {
+    searchStart = path.parentPath.node.start;
+  } else {
+    throw new Error('Unexpected AST structure');
+  }
+  const filteredComments = comments.filter(
+    c => c.start >= searchStart && c.end <= path.node.start
+  );
+  return filteredComments.length > 0 ? filteredComments : undefined;
+}
+
 module.exports = transform;

scripts/jest/preprocessor.js

@@ -4,6 +4,7 @@ const path = require('path');
 
 const babel = require('@babel/core');
 const coffee = require('coffee-script');
+const hermesParser = require('hermes-parser');
 
 const tsPreprocessor = require('./typescript/preprocessor');
 const createCacheKeyFunction = require('fbjs-scripts/jest/createCacheKeyFunction');
@@ -93,7 +94,9 @@ module.exports = {
       ) {
         plugins.push(pathToTransformReactVersionPragma);
       }
-      return babel.transform(
+      let sourceAst = hermesParser.parse(src, {babel: true});
+      return babel.transformFromAstSync(
+        sourceAst,
         src,
         Object.assign(
           {filename: path.relative(process.cwd(), filePath)},

yarn.lock

@@ -8749,7 +8749,7 @@ hermes-estree@0.9.0:
   resolved "https://registry.yarnpkg.com/hermes-estree/-/hermes-estree-0.9.0.tgz#026e0abe6db1dcf50a81a79014b779a83db3b814"
   integrity sha512-5DZ7Y0CbHVk8zPqgRCvqp8iw+P05svnQDI1aJFjdqCfXJ/1CZ+8aYpGlhJ29zCG5SE5duGTzSxogAYYI4QqXqw==
 
-hermes-parser@0.9.0:
+hermes-parser@0.9.0, hermes-parser@^0.9.0:
   version "0.9.0"
   resolved "https://registry.yarnpkg.com/hermes-parser/-/hermes-parser-0.9.0.tgz#ede3044d50479c61843cef5bbdcea83933d4e4ec"
   integrity sha512-IcvJIlAn+9tpHkP+HTsxWKrIdQPp0gvGrrQmxlL4XnNS+Oh6R/Fpxbcoflm2kY3zgQjEvxZxLiK/2+k3/5wsrw==