From 7cff189dd8bc2fb4c5a9bee83a903ae6c5807d49 Mon Sep 17 00:00:00 2001
From: Lucas Duailibe <lucasds@gmail.com>
Date: Thu, 7 Dec 2017 02:48:11 -0200
Subject: [PATCH] Print trailing comma when last arg is arrow (#3428)

---
 src/printer.js                                |  8 +++-
 .../__snapshots__/jsfmt.spec.js.snap          | 42 +++++++++++++++++++
 tests/trailing_comma/function-calls.js        |  7 ++++
 3 files changed, 55 insertions(+), 2 deletions(-)

diff --git a/src/printer.js b/src/printer.js
index e1769761..d2b3e790 100644
--- a/src/printer.js
+++ b/src/printer.js
@@ -3093,6 +3093,8 @@ function printArgumentsList(path, options, print) {
 
     const somePrintedArgumentsWillBreak = printedArguments.some(willBreak);
 
+    const maybeTrailingComma = shouldPrintComma(options, "all") ? "," : "";
+
     return concat([
       somePrintedArgumentsWillBreak ? breakParent : "",
       conditionalGroup(
@@ -3102,7 +3104,9 @@ function printArgumentsList(path, options, print) {
               indent(concat(["(", softline, concat(printedExpanded)])),
               concat(["(", concat(printedExpanded)])
             ),
-            somePrintedArgumentsWillBreak ? softline : "",
+            somePrintedArgumentsWillBreak
+              ? concat([ifBreak(maybeTrailingComma), softline])
+              : "",
             ")"
           ]),
           shouldGroupFirst
@@ -3124,7 +3128,7 @@ function printArgumentsList(path, options, print) {
             concat([
               "(",
               indent(concat([line, concat(printedArguments)])),
-              shouldPrintComma(options, "all") ? "," : "",
+              maybeTrailingComma,
               line,
               ")"
             ]),
diff --git a/tests/trailing_comma/__snapshots__/jsfmt.spec.js.snap b/tests/trailing_comma/__snapshots__/jsfmt.spec.js.snap
index 8649f223..69ccc701 100644
--- a/tests/trailing_comma/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/trailing_comma/__snapshots__/jsfmt.spec.js.snap
@@ -129,6 +129,13 @@ a(
 );
 
 a('value', 'value2', a('long-nested-value', 'long-nested-value2', 'long-nested-value3'));
+
+a.b().c(
+  {
+    d,
+  },
+  () => {}
+);
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 const a = (param1, param2, param3) => {};
 
@@ -146,6 +153,13 @@ a(
   a("long-nested-value", "long-nested-value2", "long-nested-value3")
 );
 
+a.b().c(
+  {
+    d
+  },
+  () => {}
+);
+
 `;
 
 exports[`function-calls.js 2`] = `
@@ -160,6 +174,13 @@ a(
 );
 
 a('value', 'value2', a('long-nested-value', 'long-nested-value2', 'long-nested-value3'));
+
+a.b().c(
+  {
+    d,
+  },
+  () => {}
+);
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 const a = (param1, param2, param3) => {};
 
@@ -177,6 +198,13 @@ a(
   a("long-nested-value", "long-nested-value2", "long-nested-value3"),
 );
 
+a.b().c(
+  {
+    d,
+  },
+  () => {},
+);
+
 `;
 
 exports[`function-calls.js 3`] = `
@@ -191,6 +219,13 @@ a(
 );
 
 a('value', 'value2', a('long-nested-value', 'long-nested-value2', 'long-nested-value3'));
+
+a.b().c(
+  {
+    d,
+  },
+  () => {}
+);
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 const a = (param1, param2, param3) => {};
 
@@ -208,6 +243,13 @@ a(
   a("long-nested-value", "long-nested-value2", "long-nested-value3")
 );
 
+a.b().c(
+  {
+    d,
+  },
+  () => {}
+);
+
 `;
 
 exports[`jsx.js 1`] = `
diff --git a/tests/trailing_comma/function-calls.js b/tests/trailing_comma/function-calls.js
index 86e20547..61c02117 100644
--- a/tests/trailing_comma/function-calls.js
+++ b/tests/trailing_comma/function-calls.js
@@ -9,3 +9,10 @@ a(
 );
 
 a('value', 'value2', a('long-nested-value', 'long-nested-value2', 'long-nested-value3'));
+
+a.b().c(
+  {
+    d,
+  },
+  () => {}
+);