Break Mention normalizer into its own module (with tests)

app/soapbox/normalizers/mention.ts

@@ -0,0 +1,24 @@
+/**
+ * Mention normalizer:
+ * Converts API mentions into our internal format.
+ * @see {@link https://docs.joinmastodon.org/entities/mention/}
+ */
+import {
+  Map as ImmutableMap,
+  Record as ImmutableRecord,
+} from 'immutable';
+
+import { normalizeAccount } from 'soapbox/normalizers/account';
+
+// https://docs.joinmastodon.org/entities/mention/
+const MentionRecord = ImmutableRecord({
+  id: '',
+  acct: '',
+  username: '',
+  url: '',
+});
+
+export const normalizeMention = (mention: ImmutableMap<string, any>) => {
+  // Simply normalize it as an account then cast it as a mention ¯\_(ツ)_/¯
+  return MentionRecord(normalizeAccount(mention));
+};

app/soapbox/normalizers/status.ts

@@ -11,8 +11,8 @@ import {
 } from 'immutable';
 
 import emojify from 'soapbox/features/emoji/emoji';
-import { normalizeAccount } from 'soapbox/normalizers/account';
 import { normalizeEmoji } from 'soapbox/normalizers/emoji';
+import { normalizeMention } from 'soapbox/normalizers/mention';
 import { IStatus } from 'soapbox/types';
 import { mergeDefined, makeEmojiMap } from 'soapbox/utils/normalizers';
 
@@ -73,14 +73,6 @@ const AttachmentRecord = ImmutableRecord({
   status: null,
 });
 
-// https://docs.joinmastodon.org/entities/mention/
-const MentionRecord = ImmutableRecord({
-  id: '',
-  acct: '',
-  username: '',
-  url: '',
-});
-
 // https://docs.joinmastodon.org/entities/poll/
 const PollRecord = ImmutableRecord({
   emojis: ImmutableList(),
@@ -126,11 +118,6 @@ const normalizeAttachments = (status: ImmutableMap<string, any>) => {
   });
 };
 
-// Normalize mentions
-const normalizeMention = (mention: ImmutableMap<string, any>) => {
-  return MentionRecord(normalizeAccount(mention));
-};
-
 const normalizeMentions = (status: ImmutableMap<string, any>) => {
   return status.update('mentions', ImmutableList(), mentions => {
     return mentions.map(normalizeMention);