Merge computed MemberExpression in member chain (#2670)

src/printer.js

@@ -3656,7 +3656,8 @@ function printMemberChain(path, options, print) {
     groups[0].length === 1 &&
     (groups[0][0].node.type === "ThisExpression" ||
       (groups[0][0].node.type === "Identifier" &&
-        groups[0][0].node.name.match(/(^[A-Z])|^[_$]+$/)));
+        (groups[0][0].node.name.match(/(^[A-Z])|^[_$]+$/) ||
+          (groups[1].length && groups[1][0].node.computed))));
 
   function printGroup(printedGroup) {
     return concat(printedGroup.map(tuple => tuple.printed));

tests/method-chain/__snapshots__/jsfmt.spec.js.snap

@@ -367,6 +367,35 @@ nock(/test/)
 
 `;
 
+exports[`computed-merge.js 1`] = `
+[].forEach(key => {
+  data[key]('foo')
+    .then(() => console.log('bar'))
+    .catch(() => console.log('baz'));
+});
+
+[].forEach(key => {
+  data('foo')
+    [key]('bar')
+    .then(() => console.log('bar'))
+    .catch(() => console.log('baz'));
+});
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+[].forEach(key => {
+  data[key]("foo")
+    .then(() => console.log("bar"))
+    .catch(() => console.log("baz"));
+});
+
+[].forEach(key => {
+  data("foo")
+    [key]("bar")
+    .then(() => console.log("bar"))
+    .catch(() => console.log("baz"));
+});
+
+`;
+
 exports[`first_long.js 1`] = `
 export default function theFunction(action$, store) {
   return action$.ofType(THE_ACTION).switchMap(action => Observable

tests/method-chain/computed-merge.js

@@ -0,0 +1,12 @@
+[].forEach(key => {
+  data[key]('foo')
+    .then(() => console.log('bar'))
+    .catch(() => console.log('baz'));
+});
+
+[].forEach(key => {
+  data('foo')
+    [key]('bar')
+    .then(() => console.log('bar'))
+    .catch(() => console.log('baz'));
+});