Add a GET endpoint to user preferences

Changelog: added

doc/api/users.md

@@ -453,7 +453,6 @@ Parameters:
 | `twitter`                            | No       | Twitter account                                                                                                                                         |
 | `username`                           | Yes      | Username                                                                                                                                                |
 | `view_diffs_file_by_file`            | No       | Flag indicating the user sees only one file diff per page                                                                                               |
-| `show_whitespace_in_diffs`           | No       | Flag indicating the user sees whitespace changes in diffs
 | `website_url`                        | No       | Website URL                                                                                                                                             |
 
 ## User modification
@@ -694,6 +693,29 @@ Example response:
 }
 ```
 
+## Get user preferences
+
+Get a list of currently authenticated user's preferences.
+
+```plaintext
+GET /user/preferences
+```
+
+Example response:
+
+```json
+{
+  "id": 1,
+    "user_id": 1
+      "view_diffs_file_by_file": true,
+      "show_whitespace_in_diffs": false
+}
+```
+
+Parameters:
+
+- **none**
+
 ## User preference modification
 
 Update the current user's preferences.
@@ -706,7 +728,8 @@ PUT /user/preferences
 {
   "id": 1,
     "user_id": 1
-      "view_diffs_file_by_file": true
+      "view_diffs_file_by_file": true,
+      "show_whitespace_in_diffs": false
 }
 ```
 
@@ -715,6 +738,7 @@ Parameters:
 | Attribute                    | Required | Description                                                 |
 | :--------------------------- | :------- | :---------------------------------------------------------- |
 | `view_diffs_file_by_file`    | Yes      | Flag indicating the user sees only one file diff per page.  |
+| `show_whitespace_in_diffs`   | Yes      | Flag indicating the user sees whitespace changes in diffs   |
 
 ## Set user status
 

lib/api/users.rb

@@ -1045,6 +1045,16 @@ module API
         end
       end
 
+      desc "Get the current user's preferences" do
+        success Entities::UserPreferences
+        detail 'This feature was introduced in GitLab 14.0.'
+      end
+      get "preferences", feature_category: :users do
+        authenticate!
+
+        present current_user.user_preference, with: Entities::UserPreferences
+      end
+
       desc 'Get a single email address owned by the currently authenticated user' do
         success Entities::Email
       end

spec/requests/api/users_spec.rb

@@ -2077,6 +2077,29 @@ RSpec.describe API::Users do
     it_behaves_like 'get user info', 'v4'
   end
 
+  describe "GET /user/preferences" do
+    context "when unauthenticated" do
+      it "returns authentication error" do
+        get api("/user/preferences")
+        expect(response).to have_gitlab_http_status(:unauthorized)
+      end
+    end
+
+    context "when authenticated" do
+      it "returns user preferences" do
+        user.user_preference.view_diffs_file_by_file = false
+        user.user_preference.show_whitespace_in_diffs = true
+        user.save!
+
+        get api("/user/preferences", user)
+
+        expect(response).to have_gitlab_http_status(:ok)
+        expect(json_response["view_diffs_file_by_file"]).to eq(user.user_preference.view_diffs_file_by_file)
+        expect(json_response["show_whitespace_in_diffs"]).to eq(user.user_preference.show_whitespace_in_diffs)
+      end
+    end
+  end
+
   describe "GET /user/keys" do
     context "when unauthenticated" do
       it "returns authentication error" do