api: Sync update-stream event types with doc and align implementation

src/__tests__/lib/exampleData.js

@@ -293,18 +293,25 @@ export const crossRealmBot: CrossRealmBot = makeCrossRealmBot({
 
 const randStreamId: () => number = makeUniqueRandInt('stream IDs', 1000);
 export const makeStream = (
-  args: {| stream_id?: number, name?: string, description?: string |} = Object.freeze({}),
+  args: {|
+    stream_id?: number,
+    name?: string,
+    description?: string,
+    invite_only?: boolean,
+    is_web_public?: boolean,
+    history_public_to_subscribers?: boolean,
+  |} = Object.freeze({}),
 ): Stream => {
   const name = args.name ?? randString();
   return deepFreeze({
     stream_id: args.stream_id ?? randStreamId(),
     name,
     description: args.description ?? `On the ${randString()} of ${name}`,
     rendered_description: args.description ?? `<p>On the ${randString()} of ${name}</p>`,
-    invite_only: false,
+    invite_only: args.invite_only ?? false,
     is_announcement_only: false,
-    is_web_public: false,
-    history_public_to_subscribers: true,
+    is_web_public: args.is_web_public ?? false,
+    history_public_to_subscribers: args.history_public_to_subscribers ?? true,
     first_message_id: null,
   });
 };

src/api/eventTypes.js

@@ -149,21 +149,91 @@ type StreamListEvent = $ReadOnly<{|
   streams: $ReadOnlyArray<Stream>,
 |}>;
 
+type StreamUpdateEventBase = $ReadOnly<{|
+  ...EventCommon,
+  type: typeof EventTypes.stream,
+  op: 'update',
+  stream_id: number,
+  name: string,
+|}>;
+
+// https://zulip.com/api/get-events#stream-update
+export type StreamUpdateEvent =
+  | {| ...StreamUpdateEventBase, +property: 'name', +value: $PropertyType<Stream, 'name'> |}
+  | {|
+      ...StreamUpdateEventBase,
+      +property: 'description',
+      +value: $PropertyType<Stream, 'description'>,
+      +rendered_description: $PropertyType<Stream, 'rendered_description'>,
+    |}
+  // TODO(server-4.0): New in FL 30.
+  | {|
+      ...StreamUpdateEventBase,
+      +property: 'date_created',
+      +value: $PropertyType<Stream, 'date_created'>,
+    |}
+  | {|
+      ...StreamUpdateEventBase,
+      +property: 'invite_only',
+      +value: $PropertyType<Stream, 'invite_only'>,
+      +history_public_to_subscribers: $PropertyType<Stream, 'history_public_to_subscribers'>,
+
+      // TODO(server-5.0): New in FL 71.
+      +is_web_public?: $PropertyType<Stream, 'is_web_public'>,
+    |}
+  | {|
+      ...StreamUpdateEventBase,
+      +property: 'rendered_description',
+      +value: $PropertyType<Stream, 'rendered_description'>,
+    |}
+  | {|
+      ...StreamUpdateEventBase,
+      +property: 'is_web_public',
+      +value: $PropertyType<Stream, 'is_web_public'>,
+    |}
+  // TODO(server-3.0): New in FL 1; expect is_announcement_only from older
+  //   servers.
+  | {|
+      ...StreamUpdateEventBase,
+      +property: 'stream_post_policy',
+      +value: $PropertyType<Stream, 'stream_post_policy'>,
+    |}
+  // Special values are:
+  //   *  null: default; inherits from org-level setting
+  //   * -1: unlimited retention
+  // These special values differ from updateStream's and createStream's params; see
+  //   https://chat.zulip.org/#narrow/stream/412-api-documentation/topic/message_retention_days/near/1367895
+  // TODO(server-3.0): New in FL 17.
+  | {|
+      ...StreamUpdateEventBase,
+      +property: 'message_retention_days',
+      +value: $PropertyType<Stream, 'message_retention_days'>,
+    |}
+  | {|
+      ...StreamUpdateEventBase,
+      +property: 'history_public_to_subscribers',
+      +value: $PropertyType<Stream, 'history_public_to_subscribers'>,
+    |}
+  | {|
+      ...StreamUpdateEventBase,
+      +property: 'first_message_id',
+      +value: $PropertyType<Stream, 'first_message_id'>,
+    |}
+  // TODO(server-3.0): Deprecated at FL 1; expect stream_post_policy from
+  //   newer servers.
+  | {|
+      ...StreamUpdateEventBase,
+      +property: 'is_announcement_only',
+      +value: $PropertyType<Stream, 'is_announcement_only'>,
+    |};
+
 // prettier-ignore
 export type StreamEvent =
   | {| ...StreamListEvent, +op: 'create', |}
   | {| ...StreamListEvent, +op: 'delete', |}
   | {| ...StreamListEvent, +op: 'occupy', |}
   | {| ...StreamListEvent, +op: 'vacate', |}
-  | $ReadOnly<{|
-      ...EventCommon,
-      type: typeof EventTypes.stream,
-      op: 'update',
-      stream_id: number,
-      name: string,
-      property: string,
-      value: string,
-    |}>;
+  | StreamUpdateEvent;
 
 export type UpdateMessageFlagsEvent = $ReadOnly<{|
   ...EventCommon,