Fix missing comments in assignment pattern (#704)

* Add handleAssignmentPatternComments helper function.

* Add new tests 🎉.

* Remove unecessary arg in function.

* Reorder it.

* Experimental fix for key comments in the printComments function.

* Pull master and switch to @vjeux implementation.

* Fix bad rebase.

* Add additional checking for enclosingNode in handleObjectProperty function.

src/comments.js

@@ -179,7 +179,8 @@ function attach(comments, ast, text) {
         addDanglingComment(ast, comment);
       }
     } else {
-      if (handleIfStatementComments(enclosingNode, followingNode, comment)) {
+      if (handleIfStatementComments(enclosingNode, followingNode, comment) ||
+          handleObjectProperty(enclosingNode, precedingNode, comment)) {
         // We're good
       } else if (precedingNode && followingNode) {
         // Otherwise, text exists both before and after the comment on
@@ -395,6 +396,19 @@ function handleConditionalExpressionComments(
   return false;
 }
 
+function handleObjectProperty(enclosingNode, precedingNode, comment) {
+  if (enclosingNode &&
+      (enclosingNode.type === "ObjectProperty" ||
+       enclosingNode.type === "Property") &&
+      enclosingNode.shorthand &&
+      enclosingNode.key === precedingNode &&
+      enclosingNode.value.type === "AssignmentPattern") {
+    addTrailingComment(enclosingNode.value.left, comment);
+    return true;
+  }
+  return false;
+}
+
 function printComment(commentPath) {
   const comment = commentPath.getValue();
   comment.printed = true;

tests/comments/__snapshots__/jsfmt.spec.js.snap

@@ -1087,3 +1087,25 @@ try {
 }
 "
 `;
+
+exports[`test assignment-pattern.js 1`] = `
+"const { a /* comment */ = 1 } = b;
+
+const { c = 1 /* comment */ } = d;
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+const { a /* comment */ = 1 } = b;
+
+const { c = 1 /* comment */ } = d;
+"
+`;
+
+exports[`test assignment-pattern.js 2`] = `
+"const { a /* comment */ = 1 } = b;
+
+const { c = 1 /* comment */ } = d;
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+const { a /* comment */ = 1 } = b;
+
+const { c = 1 /* comment */ } = d;
+"
+`;

tests/comments/assignment-pattern.js

@@ -0,0 +1,3 @@
+const { a /* comment */ = 1 } = b;
+
+const { c = 1 /* comment */ } = d;