Add JSON API support for timezone update (#2806)

* Add JSON API support for timezone update

* Simplify timezone controller to just head :no_content

* Use PUT instead of PATCH in timezone tests to match docs

* Use PATCH instead of PUT for timezone endpoint

Reverts tests to use patch and updates docs heading to PATCH
for consistency.

app/controllers/my/timezones_controller.rb

@@ -1,6 +1,7 @@
 class My::TimezonesController < ApplicationController
   def update
     Current.user.settings.update!(timezone_name: timezone_param)
+    head :no_content
   end
 
   private

docs/api/sections/identity.md

@@ -44,3 +44,23 @@ __Response:__
   ]
 }
 ```
+
+## `PATCH /my/timezone`
+
+Updates the current user's timezone. This affects how times are displayed in notification emails.
+
+| Parameter | Type | Required | Description |
+|-----------|------|----------|-------------|
+| `timezone_name` | string | Yes | IANA timezone identifier (e.g. `America/New_York`, `Europe/London`, `Asia/Tokyo`) |
+
+__Request:__
+
+```json
+{
+  "timezone_name": "America/New_York"
+}
+```
+
+__Response:__
+
+Returns `204 No Content` on success.

test/controllers/my/timezones_controller_test.rb

@@ -12,4 +12,11 @@ class My::TimezonesControllerTest < ActionDispatch::IntegrationTest
     patch my_timezone_path, params: { timezone_name: "America/New_York" }
     assert_equal time_zone, users(:kevin).reload.timezone
   end
+
+  test "update as JSON" do
+    assert_not_equal ActiveSupport::TimeZone["America/Chicago"], users(:kevin).timezone
+    patch my_timezone_path, params: { timezone_name: "America/Chicago" }, as: :json
+    assert_response :no_content
+    assert_equal ActiveSupport::TimeZone["America/Chicago"], users(:kevin).reload.timezone
+  end
 end