react-update-imports: Don't remove leading comments

Author: gaearon

transforms/__testfixtures__/update-react-imports/leading-comment.input.js

@@ -0,0 +1,7 @@
+/**
+ * Hello world.
+ */
+
+import * as React from "react";
+
+<div></div>;

transforms/__testfixtures__/update-react-imports/leading-comment.output.js

@@ -0,0 +1,5 @@
+/**
+ * Hello world.
+ */
+
+<div></div>;

transforms/__tests__/update-react-imports-test.js

@@ -15,6 +15,7 @@ const tests = [
  'flow-default-and-type-specifier-import',
  'jsx-element',
  'jsx-fragment',
+ 'leading-comment',
  'react-basic-default-export-jsx-element-react-variable',
  'react-basic-default-export-jsx-element',
  'react-basic-default-export',

transforms/update-react-imports.js

@@ -11,6 +11,15 @@ module.exports = function(file, api, options) {
  const printOptions = options.printOptions || {};
  const root = j(file.source);
 
+ // https://github.com/facebook/jscodeshift/blob/master/recipes/retain-first-comment.md
+ function getFirstNode() {
+ return root.find(j.Program).get('body', 0).node;
+ }
+
+ // Save the comments attached to the first node
+ const firstNode = getFirstNode();
+ const { comments } = firstNode;
+
  function isVariableDeclared(variable) {
  return (
  root
@@ -355,6 +364,12 @@ module.exports = function(file, api, options) {
  return null;
  }
  }
- 
+
+ // If the first node has been modified or deleted, reattach the comments
+ const firstNode2 = getFirstNode();
+ if (firstNode2 !== firstNode) {
+ firstNode2.comments = comments;
+ }
+
  return root.toSource(printOptions);
 };