From 504d75103642deab79f9da6512175027a5efd7bb Mon Sep 17 00:00:00 2001
From: Sosuke Suzuki <aosukeke@gmail.com>
Date: Fri, 29 Apr 2022 17:42:42 +0900
Subject: [PATCH] Preserve blank line between export specifiers (#12746)

* Preserve blank line between export specifiers

* Add changelog

* rename
---
 changelog_unreleased/javascript/12746.md      |  33 ++++++
 src/language-js/comments.js                   |  15 ++-
 .../export/__snapshots__/jsfmt.spec.js.snap   | 109 ++++++++++++++++++
 .../export/blank-line-between-specifiers.js   |  21 ++++
 4 files changed, 172 insertions(+), 6 deletions(-)
 create mode 100644 changelog_unreleased/javascript/12746.md
 create mode 100644 tests/format/js/export/blank-line-between-specifiers.js

diff --git a/changelog_unreleased/javascript/12746.md b/changelog_unreleased/javascript/12746.md
new file mode 100644
index 000000000..d7b895ef7
--- /dev/null
+++ b/changelog_unreleased/javascript/12746.md
@@ -0,0 +1,33 @@
+#### Preserve blank line between export specifiers (#12746 by @sosukesuzuki)
+
+<!-- prettier-ignore -->
+```jsx
+// Input
+export {
+  // a
+  foo1,
+
+  // b
+  bar1,
+  baz1,
+} from "mod";
+
+// Prettier stable
+export {
+  // a
+  foo1,
+  // b
+  bar1,
+  baz1,
+} from "mod";
+
+// Prettier main
+export {
+  // a
+  foo1,
+
+  // b
+  bar1,
+  baz1,
+} from "mod";
+```
diff --git a/src/language-js/comments.js b/src/language-js/comments.js
index 4a23aba07..22b1bed4b 100644
--- a/src/language-js/comments.js
+++ b/src/language-js/comments.js
@@ -65,7 +65,7 @@ function handleOwnLineComment(context) {
     handleForComments,
     handleUnionTypeComments,
     handleOnlyComments,
-    handleImportDeclarationComments,
+    handleModuleSpecifiersComments,
     handleAssignmentPatternComments,
     handleMethodNameComments,
     handleLabeledStatementComments,
@@ -787,17 +787,20 @@ function handleForComments({ comment, enclosingNode }) {
   return false;
 }
 
-function handleImportDeclarationComments({
+function handleModuleSpecifiersComments({
   comment,
   precedingNode,
   enclosingNode,
   text,
 }) {
+  const isImportDeclaration =
+    precedingNode?.type === "ImportSpecifier" &&
+    enclosingNode?.type === "ImportDeclaration";
+  const isExportDeclaration =
+    precedingNode?.type === "ExportSpecifier" &&
+    enclosingNode?.type === "ExportNamedDeclaration";
   if (
-    precedingNode &&
-    precedingNode.type === "ImportSpecifier" &&
-    enclosingNode &&
-    enclosingNode.type === "ImportDeclaration" &&
+    (isImportDeclaration || isExportDeclaration) &&
     hasNewline(text, locEnd(comment))
   ) {
     addTrailingComment(precedingNode, comment);
diff --git a/tests/format/js/export/__snapshots__/jsfmt.spec.js.snap b/tests/format/js/export/__snapshots__/jsfmt.spec.js.snap
index f34ad6b8c..ae949438c 100644
--- a/tests/format/js/export/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/format/js/export/__snapshots__/jsfmt.spec.js.snap
@@ -1,5 +1,114 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
+exports[`blank-line-between-specifiers.js - {"bracketSpacing":false} format 1`] = `
+====================================options=====================================
+bracketSpacing: false
+parsers: ["babel", "flow", "typescript"]
+printWidth: 80
+                                                                                | printWidth
+=====================================input======================================
+export {
+  // a
+  foo1,
+
+  // b
+  bar1,
+  baz1,
+} from "mod";
+
+const foo2 = 1;
+const bar2 = 1;
+const baz2 = 1;
+
+export {
+  // a
+  foo2,
+
+  // b
+  bar2,
+  baz2,
+};
+
+=====================================output=====================================
+export {
+  // a
+  foo1,
+
+  // b
+  bar1,
+  baz1,
+} from "mod";
+
+const foo2 = 1;
+const bar2 = 1;
+const baz2 = 1;
+
+export {
+  // a
+  foo2,
+
+  // b
+  bar2,
+  baz2,
+};
+
+================================================================================
+`;
+
+exports[`blank-line-between-specifiers.js format 1`] = `
+====================================options=====================================
+parsers: ["babel", "flow", "typescript"]
+printWidth: 80
+                                                                                | printWidth
+=====================================input======================================
+export {
+  // a
+  foo1,
+
+  // b
+  bar1,
+  baz1,
+} from "mod";
+
+const foo2 = 1;
+const bar2 = 1;
+const baz2 = 1;
+
+export {
+  // a
+  foo2,
+
+  // b
+  bar2,
+  baz2,
+};
+
+=====================================output=====================================
+export {
+  // a
+  foo1,
+
+  // b
+  bar1,
+  baz1,
+} from "mod";
+
+const foo2 = 1;
+const bar2 = 1;
+const baz2 = 1;
+
+export {
+  // a
+  foo2,
+
+  // b
+  bar2,
+  baz2,
+};
+
+================================================================================
+`;
+
 exports[`bracket.js - {"bracketSpacing":false} format 1`] = `
 ====================================options=====================================
 bracketSpacing: false
diff --git a/tests/format/js/export/blank-line-between-specifiers.js b/tests/format/js/export/blank-line-between-specifiers.js
new file mode 100644
index 000000000..82cd20637
--- /dev/null
+++ b/tests/format/js/export/blank-line-between-specifiers.js
@@ -0,0 +1,21 @@
+export {
+  // a
+  foo1,
+
+  // b
+  bar1,
+  baz1,
+} from "mod";
+
+const foo2 = 1;
+const bar2 = 1;
+const baz2 = 1;
+
+export {
+  // a
+  foo2,
+
+  // b
+  bar2,
+  baz2,
+};