getMessages [nfc]: Plumb identity down to migrateMessages.

Soon, we'll need this to construct AvatarURL instances as part of
our validation-at-the-edge in the crunchy shell pattern [1]. In
particular, it gives us the realm, which we'll use to point to
uploaded avatars.

[1] https://github.com/zulip/zulip-mobile/blob/master/docs/architecture/crunchy-shell.md

src/api/messages/__tests__/migrateMessages-test.js

@@ -2,6 +2,7 @@
 import omit from 'lodash.omit';
 
 import { migrateMessages } from '../getMessages';
+import { identityOfAuth } from '../../../account/accountMisc';
 import * as eg from '../../../__tests__/lib/exampleData';
 import type { ServerMessage, ServerReaction } from '../getMessages';
 import type { Message } from '../../modelTypes';
@@ -47,7 +48,7 @@ describe('migrateMessages', () => {
     },
   ];
 
-  const actualOutput: Message[] = migrateMessages(input);
+  const actualOutput: Message[] = migrateMessages(input, identityOfAuth(eg.selfAuth));
 
   test('Replace user object with `user_id`', () => {
     expect(actualOutput.map(m => m.reactions)).toEqual(expectedOutput.map(m => m.reactions));

src/api/messages/getMessages.js

@@ -1,8 +1,10 @@
 /* @flow strict-local */
 import type { Auth, ApiResponseSuccess } from '../transportTypes';
+import type { Identity } from '../../types';
 import type { Message, Narrow } from '../apiTypes';
 import type { Reaction } from '../modelTypes';
 import { apiGet } from '../apiFetch';
+import { identityOfAuth } from '../../account/accountMisc';
 
 type ApiResponseMessages = {|
   ...ApiResponseSuccess,
@@ -41,7 +43,7 @@ type ServerApiResponseMessages = {|
 |};
 
 /** Exported for tests only. */
-export const migrateMessages = (messages: ServerMessage[]): Message[] =>
+export const migrateMessages = (messages: ServerMessage[], identity: Identity): Message[] =>
   messages.map(message => {
     const { reactions, ...restMessage } = message;
     return {
@@ -56,11 +58,11 @@ export const migrateMessages = (messages: ServerMessage[]): Message[] =>
     };
   });
 
-const migrateResponse = response => {
+const migrateResponse = (response, identity: Identity) => {
   const { messages, ...restResponse } = response;
   return {
     ...restResponse,
-    messages: migrateMessages(messages),
+    messages: migrateMessages(messages, identity),
   };
 };
 
@@ -91,5 +93,5 @@ export default async (
     apply_markdown: true,
     use_first_unread_anchor: useFirstUnread,
   });
-  return migrateResponse(response);
+  return migrateResponse(response, identityOfAuth(auth));
 };