Properly support member chains comments (#668)

When there is a comment right before the first `.`, we want to force break such that the comment is printed on its own line.

Note: this needs to be based on-top of #667 as it always indent the first `.`

Fixes #613

src/printer.js

@@ -2253,12 +2253,12 @@ function printMemberChain(path, options, print) {
   }
 
   const printedGroups = groups.map(printGroup);
-
   const oneLine = concat(printedGroups);
+  const hasComment = groups.length >= 2 && groups[1][0].node.comments;
 
   // If we only have a single `.`, we shouldn't do anything fancy and just
   // render everything concatenated together.
-  if (groups.length <= 2) {
+  if (groups.length <= 2 && !hasComment) {
     return group(oneLine);
   }
 
@@ -2268,6 +2268,11 @@ function printMemberChain(path, options, print) {
     printIndentedGroup(groups.slice(shouldMerge ? 2 : 1), hardline)
   ]);
 
+  // If there's a comment, we don't want to print in one line.
+  if (hasComment) {
+    return group(expanded);
+  }
+
   // If any group but the last one has a hard line, we want to force expand
   // it. If the last group is a function it's okay to inline if it fits.
   if (printedGroups.slice(0, -1).some(willBreak)) {

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

@@ -364,14 +364,12 @@ export type BuckWebSocketMessage =
     };
 
 // Missing one level of indentation because of the comment
-const rootEpic = (actions, store) => combineEpics(...epics)(
-  actions,
-  store
-)// Log errors and continue.
-.catch((err, stream) => {
-  getLogger().error(err);
-  return stream;
-});
+const rootEpic = (actions, store) => combineEpics(...epics)(actions, store)
+  // Log errors and continue.
+  .catch((err, stream) => {
+    getLogger().error(err);
+    return stream;
+  });
 
 // Two extra levels of indentation because of the comment
 export type AsyncExecuteOptions =
@@ -593,14 +591,12 @@ export type BuckWebSocketMessage =
     };
 
 // Missing one level of indentation because of the comment
-const rootEpic = (actions, store) => combineEpics(...epics)(
-  actions,
-  store
-)// Log errors and continue.
-.catch((err, stream) => {
-  getLogger().error(err);
-  return stream;
-});
+const rootEpic = (actions, store) => combineEpics(...epics)(actions, store)
+  // Log errors and continue.
+  .catch((err, stream) => {
+    getLogger().error(err);
+    return stream;
+  });
 
 // Two extra levels of indentation because of the comment
 export type AsyncExecuteOptions =

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

@@ -115,6 +115,23 @@ it(\"should group messages with same created time\", () => {
 "
 `;
 
+exports[`test comment.js 1`] = `
+"function f() {
+  return observableFromSubscribeFunction()
+    // Debounce manually rather than using editor.onDidStopChanging so that the debounce time is
+    // configurable.
+    .debounceTime(debounceInterval);
+}
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+function f() {
+  return observableFromSubscribeFunction()
+    // Debounce manually rather than using editor.onDidStopChanging so that the debounce time is
+    // configurable.
+    .debounceTime(debounceInterval);
+}
+"
+`;
+
 exports[`test first_long.js 1`] = `
 "export default function theFunction(action$, store) {
   return action$.ofType(THE_ACTION).switchMap(action => Observable

tests/method-chain/comment.js

@@ -0,0 +1,6 @@
+function f() {
+  return observableFromSubscribeFunction()
+    // Debounce manually rather than using editor.onDidStopChanging so that the debounce time is
+    // configurable.
+    .debounceTime(debounceInterval);
+}