Simplify arrow functions that use blocks (fixes #268) (#496)

src/printer.js

@@ -284,7 +284,8 @@ function genericPrintNoParens(path, options, print) {
       if (
         n.body.type === "ArrayExpression" ||
           n.body.type === "ObjectExpression" ||
-          n.body.type === "JSXElement"
+          n.body.type === "JSXElement" ||
+          n.body.type === "BlockStatement"
       ) {
         return group(collapsed);
       }

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

@@ -34,3 +34,19 @@ veryLongCall(
 );
 "
 `;
+
+exports[`test long-contents.js 1`] = `
+"const foo = () => {
+  expect(arg1, arg2, arg3).toEqual({message: \'test\', messageType: \'SMS\', status: \'Unknown\', created: \'11/01/2017 13:36\'});
+};
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+const foo = () => {
+  expect(arg1, arg2, arg3).toEqual({
+    message: \"test\",
+    messageType: \"SMS\",
+    status: \"Unknown\",
+    created: \"11/01/2017 13:36\"
+  });
+};
+"
+`;

tests/arrows/long-contents.js

@@ -0,0 +1,3 @@
+const foo = () => {
+  expect(arg1, arg2, arg3).toEqual({message: 'test', messageType: 'SMS', status: 'Unknown', created: '11/01/2017 13:36'});
+};