Review updates and cleanupce-57402-add-issues-statistics-api-endpoints

* Cleaned issues and issues_statistics docs
* Renamed param with_labels_data to with_labels_details
* Added spec for N+1 check when retrieving labels from issue
* Refactoed CheckAssigneesCount validation class

8 files changed, 93 insertions, 97 deletions

diff --git a/doc/api/issues.md b/doc/api/issues.md
index 936caef7601..4fb3626f637 100644
--- a/doc/api/issues.md
+++ b/doc/api/issues.md
@@ -39,7 +39,7 @@ GET /issues?confidential=true
 | ------------------- | ---------------- | ---------- | --------------------------------------------------------------------------------------------------------------------------------------------------- |
 | `state`             | string           | no         | Return `all` issues or just those that are `opened` or `closed`                                                                                       |
 | `labels`            | string           | no         | Comma-separated list of label names, issues must have all labels to be returned. `None` lists all issues with no labels. `Any` lists all issues with at least one label. `No+Label` (Deprecated) lists all issues with no labels. Predefined names are case-insensitive. |
-| `with_labels_data`  | Boolean          | no         | If `true`, response will return more details for each label in labels field: `:name`, `:color`, `:description`, `:text_color`. Default is `false`. |
+| `with_labels_details`| Boolean          | no         | If `true`, response will return more details for each label in labels field: `:name`, `:color`, `:description`, `:text_color`. Default is `false`. |
 | `milestone`         | string           | no         | The milestone title. `None` lists all issues with no milestone. `Any` lists all issues that have an assigned milestone.                             |
 | `scope`             | string           | no         | Return issues for the given scope: `created_by_me`, `assigned_to_me` or `all`. Defaults to `created_by_me`<br> For versions before 11.0, use the now deprecated `created-by-me` or `assigned-to-me` scopes instead.<br> _([Introduced][ce-13004] in GitLab 9.5. [Changed to snake_case][ce-18935] in GitLab 11.0)_ |
 | `author_id`         | integer          | no         | Return issues created by the given user `id`. Mutually exclusive with `author_username`. Combine with `scope=all` or `scope=assigned_to_me`. _([Introduced][ce-13004] in GitLab 9.5)_ |
@@ -170,7 +170,7 @@ GET /groups/:id/issues?confidential=true
 | `id`                | integer/string   | yes        | The ID or [URL-encoded path of the group](README.md#namespaced-path-encoding) owned by the authenticated user                 |
 | `state`             | string           | no         | Return all issues or just those that are `opened` or `closed`                                                                 |
 | `labels`            | string           | no         | Comma-separated list of label names, issues must have all labels to be returned. `None` lists all issues with no labels. `Any` lists all issues with at least one label. `No+Label` (Deprecated) lists all issues with no labels. Predefined names are case-insensitive. |
-| `with_labels_data`  | Boolean          | no         | If `true`, response will return more details for each label in labels field: `:name`, `:color`, `:description`, `:text_color`. Default is `false`. |
+| `with_labels_details`| Boolean          | no         | If `true`, response will return more details for each label in labels field: `:name`, `:color`, `:description`, `:text_color`. Default is `false`. |
 | `iids[]`            | Array[integer]   | no         | Return only the issues having the given `iid`                                                                                 |
 | `milestone`         | string           | no         | The milestone title. `None` lists all issues with no milestone. `Any` lists all issues that have an assigned milestone.       |
 | `scope`             | string           | no         | Return issues for the given scope: `created_by_me`, `assigned_to_me` or `all`.<br> For versions before 11.0, use the now deprecated `created-by-me` or `assigned-to-me` scopes instead.<br> _([Introduced][ce-13004] in GitLab 9.5. [Changed to snake_case][ce-18935] in GitLab 11.0)_ |
@@ -301,7 +301,7 @@ GET /projects/:id/issues?confidential=true
 | `iids[]`            | Array[integer]   | no         | Return only the milestone having the given `iid`                                                                              |
 | `state`             | string           | no         | Return all issues or just those that are `opened` or `closed`                                                                 |
 | `labels`            | string           | no         | Comma-separated list of label names, issues must have all labels to be returned. `None` lists all issues with no labels. `Any` lists all issues with at least one label. `No+Label` (Deprecated) lists all issues with no labels. Predefined names are case-insensitive. |
-| `with_labels_data`  | Boolean          | no         | If `true`, response will return more details for each label in labels field: `:name`, `:color`, `:description`, `:text_color`. Default is `false`. |
+| `with_labels_details`| Boolean          | no         | If `true`, response will return more details for each label in labels field: `:name`, `:color`, `:description`, `:text_color`. Default is `false`. |
 | `milestone`         | string           | no         | The milestone title. `None` lists all issues with no milestone. `Any` lists all issues that have an assigned milestone.       |
 | `scope`             | string           | no         | Return issues for the given scope: `created_by_me`, `assigned_to_me` or `all`.<br> For versions before 11.0, use the now deprecated `created-by-me` or `assigned-to-me` scopes instead.<br> _([Introduced][ce-13004] in GitLab 9.5. [Changed to snake_case][ce-18935] in GitLab 11.0)_ |
 | `author_id`         | integer          | no         | Return issues created by the given user `id`. Mutually exclusive with `author_username`. Combine with `scope=all` or `scope=assigned_to_me`. _([Introduced][ce-13004] in GitLab 9.5)_ |
diff --git a/doc/api/issues_statistics.md b/doc/api/issues_statistics.md
index 1eeb1338104..82bc9c142cc 100644
--- a/doc/api/issues_statistics.md
+++ b/doc/api/issues_statistics.md
@@ -28,14 +28,14 @@ GET /issues_statistics?confidential=true
 
 | Attribute           | Type             | Required   | Description                                                                                                                                         |
 | ------------------- | ---------------- | ---------- | --------------------------------------------------------------------------------------------------------------------------------------------------- |
-| `labels`            | string           | no         | Comma-separated list of label names, issues must have all labels to be returned. `None` lists all issues with no labels. `Any` lists all issues with at least one label. `No+Label` (Deprecated) lists all issues with no labels. Predefined names are case-insensitive. |
+| `labels`            | string           | no         | Comma-separated list of label names, issues must have all labels to be returned. `None` lists all issues with no labels. `Any` lists all issues with at least one label. |
 | `milestone`         | string           | no         | The milestone title. `None` lists all issues with no milestone. `Any` lists all issues that have an assigned milestone.                             |
-| `scope`             | string           | no         | Return issues for the given scope: `created_by_me`, `assigned_to_me` or `all`. Defaults to `created_by_me`<br> For versions before 11.0, use the now deprecated `created-by-me` or `assigned-to-me` scopes instead.<br> _([Introduced][ce-13004] in GitLab 9.5. [Changed to snake_case][ce-18935] in GitLab 11.0)_ |
-| `author_id`         | integer          | no         | Return issues created by the given user `id`. Mutually exclusive with `author_username`. Combine with `scope=all` or `scope=assigned_to_me`. _([Introduced][ce-13004] in GitLab 9.5)_ |
-| `author_username`   | string           | no         | Return issues created by the given `username`. Simillar to `author_id` and mutually exclusive with `author_id`. |
-| `assignee_id`       | integer          | no         | Return issues assigned to the given user `id`. Mutually exclusive with `assignee_username`. `None` returns unassigned issues. `Any` returns issues with an assignee. _([Introduced][ce-13004] in GitLab 9.5)_ |
-| `assignee_username` | Array[String]    | no         | Return issues assigned to the given `username`. Simillar to `assignee_id` and mutually exclusive with `assignee_id`. In CE version `assignee_username` array should only contain a single value or an invalid param error will be returned otherwise. |
-| `my_reaction_emoji` | string           | no         | Return issues reacted by the authenticated user by the given `emoji`. `None` returns issues not given a reaction. `Any` returns issues given at least one reaction. _([Introduced][ce-14016] in GitLab 10.0)_ |
+| `scope`             | string           | no         | Return issues for the given scope: `created_by_me`, `assigned_to_me` or `all`. Defaults to `created_by_me` |
+| `author_id`         | integer          | no         | Return issues created by the given user `id`. Mutually exclusive with `author_username`. Combine with `scope=all` or `scope=assigned_to_me`. |
+| `author_username`   | string           | no         | Return issues created by the given `username`. Similar to `author_id` and mutually exclusive with `author_id`. |
+| `assignee_id`       | integer          | no         | Return issues assigned to the given user `id`. Mutually exclusive with `assignee_username`. `None` returns unassigned issues. `Any` returns issues with an assignee. |
+| `assignee_username` | Array[String]    | no         | Return issues assigned to the given `username`. Similar to `assignee_id` and mutually exclusive with `assignee_id`. In CE version `assignee_username` array should only contain a single value or an invalid param error will be returned otherwise. |
+| `my_reaction_emoji` | string           | no         | Return issues reacted by the authenticated user by the given `emoji`. `None` returns issues not given a reaction. `Any` returns issues given at least one reaction. |
 | `iids[]`            | Array[integer]   | no         | Return only the issues having the given `iid`                                                                                                       |
 | `search`            | string           | no         | Search issues against their `title` and `description`                                                                                               |
 | `in`                | string           | no         | Modify the scope of the `search` attribute. `title`, `description`, or a string joining them with comma. Default is `title,description`             |
@@ -63,13 +63,9 @@ Example response:
 }
 ```
 
-**Note**: `assignee` column is deprecated, now we show it as a single-sized array `assignees` to conform to the GitLab EE API.
+## Get group issues statistics
 
-**Note**: The `closed_by` attribute was [introduced in GitLab 10.6][ce-17042]. This value will only be present for issues which were closed after GitLab 10.6 and when the user account that closed the issue still exists.
-
-## List group issues
-
-Get a list of a group's issues.
+Gets issues count statistics for given group.
 
 ```
 GET /groups/:id/issues_statistics
@@ -89,15 +85,15 @@ GET /groups/:id/issues_statistics?confidential=true
 | Attribute           | Type             | Required   | Description                                                                                                                   |
 | ------------------- | ---------------- | ---------- | ----------------------------------------------------------------------------------------------------------------------------- |
 | `id`                | integer/string   | yes        | The ID or [URL-encoded path of the group](README.md#namespaced-path-encoding) owned by the authenticated user                 |
-| `labels`            | string           | no         | Comma-separated list of label names, issues must have all labels to be returned. `None` lists all issues with no labels. `Any` lists all issues with at least one label. `No+Label` (Deprecated) lists all issues with no labels. Predefined names are case-insensitive. |
+| `labels`            | string           | no         | Comma-separated list of label names, issues must have all labels to be returned. `None` lists all issues with no labels. `Any` lists all issues with at least one label. |
 | `iids[]`            | Array[integer]   | no         | Return only the issues having the given `iid`                                                                                 |
 | `milestone`         | string           | no         | The milestone title. `None` lists all issues with no milestone. `Any` lists all issues that have an assigned milestone.       |
-| `scope`             | string           | no         | Return issues for the given scope: `created_by_me`, `assigned_to_me` or `all`.<br> For versions before 11.0, use the now deprecated `created-by-me` or `assigned-to-me` scopes instead.<br> _([Introduced][ce-13004] in GitLab 9.5. [Changed to snake_case][ce-18935] in GitLab 11.0)_ |
-| `author_id`         | integer          | no         | Return issues created by the given user `id`. Mutually exclusive with `author_username`. Combine with `scope=all` or `scope=assigned_to_me`. _([Introduced][ce-13004] in GitLab 9.5)_ |
-| `author_username`   | string           | no         | Return issues created by the given `username`. Simillar to `author_id` and mutually exclusive with `author_id`. |
-| `assignee_id`       | integer          | no         | Return issues assigned to the given user `id`. Mutually exclusive with `assignee_username`. `None` returns unassigned issues. `Any` returns issues with an assignee. _([Introduced][ce-13004] in GitLab 9.5)_ |
-| `assignee_username` | Array[String]    | no         | Return issues assigned to the given `username`. Simillar to `assignee_id` and mutually exclusive with `assignee_id`. In CE version `assignee_username` array should only contain a single value or an invalid param error will be returned otherwise. |
-| `my_reaction_emoji` | string           | no         | Return issues reacted by the authenticated user by the given `emoji`. `None` returns issues not given a reaction. `Any` returns issues given at least one reaction. _([Introduced][ce-14016] in GitLab 10.0)_ |
+| `scope`             | string           | no         | Return issues for the given scope: `created_by_me`, `assigned_to_me` or `all`. |
+| `author_id`         | integer          | no         | Return issues created by the given user `id`. Mutually exclusive with `author_username`. Combine with `scope=all` or `scope=assigned_to_me`. |
+| `author_username`   | string           | no         | Return issues created by the given `username`. Similar to `author_id` and mutually exclusive with `author_id`. |
+| `assignee_id`       | integer          | no         | Return issues assigned to the given user `id`. Mutually exclusive with `assignee_username`. `None` returns unassigned issues. `Any` returns issues with an assignee. |
+| `assignee_username` | Array[String]    | no         | Return issues assigned to the given `username`. Similar to `assignee_id` and mutually exclusive with `assignee_id`. In CE version `assignee_username` array should only contain a single value or an invalid param error will be returned otherwise. |
+| `my_reaction_emoji` | string           | no         | Return issues reacted by the authenticated user by the given `emoji`. `None` returns issues not given a reaction. `Any` returns issues given at least one reaction. |
 | `search`            | string           | no         | Search group issues against their `title` and `description`                                                                   |
 | `created_after`     | datetime         | no         | Return issues created on or after the given time                                                                              |
 | `created_before`    | datetime         | no         | Return issues created on or before the given time                                                                             |
@@ -123,13 +119,9 @@ Example response:
 }
 ```
 
-**Note**: `assignee` column is deprecated, now we show it as a single-sized array `assignees` to conform to the GitLab EE API.
-
-**Note**: The `closed_by` attribute was [introduced in GitLab 10.6][ce-17042]. This value will only be present for issues which were closed after GitLab 10.6 and when the user account that closed the issue still exists.
-
-## List project issues
+## Get project issues statistics
 
-Get a list of a project's issues.
+Gets issues count statistics for given project.
 
 ```
 GET /projects/:id/issues_statistics
@@ -150,14 +142,14 @@ GET /projects/:id/issues_statistics?confidential=true
 | ------------------- | ---------------- | ---------- | ----------------------------------------------------------------------------------------------------------------------------- |
 | `id`                | integer/string   | yes        | The ID or [URL-encoded path of the project](README.md#namespaced-path-encoding) owned by the authenticated user               |
 | `iids[]`            | Array[integer]   | no         | Return only the milestone having the given `iid`                                                                              |
-| `labels`            | string           | no         | Comma-separated list of label names, issues must have all labels to be returned. `None` lists all issues with no labels. `Any` lists all issues with at least one label. `No+Label` (Deprecated) lists all issues with no labels. Predefined names are case-insensitive. |
+| `labels`            | string           | no         | Comma-separated list of label names, issues must have all labels to be returned. `None` lists all issues with no labels. `Any` lists all issues with at least one label. |
 | `milestone`         | string           | no         | The milestone title. `None` lists all issues with no milestone. `Any` lists all issues that have an assigned milestone.       |
-| `scope`             | string           | no         | Return issues for the given scope: `created_by_me`, `assigned_to_me` or `all`.<br> For versions before 11.0, use the now deprecated `created-by-me` or `assigned-to-me` scopes instead.<br> _([Introduced][ce-13004] in GitLab 9.5. [Changed to snake_case][ce-18935] in GitLab 11.0)_ |
-| `author_id`         | integer          | no         | Return issues created by the given user `id`. Mutually exclusive with `author_username`. Combine with `scope=all` or `scope=assigned_to_me`. _([Introduced][ce-13004] in GitLab 9.5)_ |
-| `author_username`   | string           | no         | Return issues created by the given `username`. Simillar to `author_id` and mutually exclusive with `author_id`. |
-| `assignee_id`       | integer          | no         | Return issues assigned to the given user `id`. Mutually exclusive with `assignee_username`. `None` returns unassigned issues. `Any` returns issues with an assignee. _([Introduced][ce-13004] in GitLab 9.5)_ |
-| `assignee_username` | Array[String]    | no         | Return issues assigned to the given `username`. Simillar to `assignee_id` and mutually exclusive with `assignee_id`. In CE version `assignee_username` array should only contain a single value or an invalid param error will be returned otherwise. |
-| `my_reaction_emoji` | string           | no         | Return issues reacted by the authenticated user by the given `emoji`. `None` returns issues not given a reaction. `Any` returns issues given at least one reaction. _([Introduced][ce-14016] in GitLab 10.0)_ |
+| `scope`             | string           | no         | Return issues for the given scope: `created_by_me`, `assigned_to_me` or `all`. |
+| `author_id`         | integer          | no         | Return issues created by the given user `id`. Mutually exclusive with `author_username`. Combine with `scope=all` or `scope=assigned_to_me`. |
+| `author_username`   | string           | no         | Return issues created by the given `username`. Similar to `author_id` and mutually exclusive with `author_id`. |
+| `assignee_id`       | integer          | no         | Return issues assigned to the given user `id`. Mutually exclusive with `assignee_username`. `None` returns unassigned issues. `Any` returns issues with an assignee. |
+| `assignee_username` | Array[String]    | no         | Return issues assigned to the given `username`. Similar to `assignee_id` and mutually exclusive with `assignee_id`. In CE version `assignee_username` array should only contain a single value or an invalid param error will be returned otherwise. |
+| `my_reaction_emoji` | string           | no         | Return issues reacted by the authenticated user by the given `emoji`. `None` returns issues not given a reaction. `Any` returns issues given at least one reaction. |
 | `search`            | string           | no         | Search project issues against their `title` and `description`                                                                 |
 | `created_after`     | datetime         | no         | Return issues created on or after the given time                                                                              |
 | `created_before`    | datetime         | no         | Return issues created on or before the given time                                                                             |
@@ -183,8 +175,3 @@ Example response:
   }
 }
 ```
-
-**Note**: `assignee` column is deprecated, now we show it as a single-sized array `assignees` to conform to the GitLab EE API.
-
-**Note**: The `closed_by` attribute was [introduced in GitLab 10.6][ce-17042]. This value will only be present for issues which were closed after GitLab 10.6 and when the user account that closed the issue still exists.
-
diff --git a/lib/api/entities.rb b/lib/api/entities.rb
index 1f10dc6c0fc..625fada4f08 100644
--- a/lib/api/entities.rb
+++ b/lib/api/entities.rb
@@ -542,10 +542,15 @@ module API
     class IssueBasic < ProjectEntity
       expose :closed_at
       expose :closed_by, using: Entities::UserBasic
-      expose :labels do |issue|
-        # Avoids an N+1 query since labels are preloaded
-        issue.labels.map(&:title).sort
+
+      expose :labels do |issue, options|
+        if options[:with_labels_details]
+          ::API::Entities::LabelBasic.represent(issue.labels.sort_by(&:title))
+        else
+          issue.labels.map(&:title).sort
+        end
       end
+
       expose :milestone, using: Entities::Milestone
       expose :assignees, :author, using: Entities::UserBasic
 
@@ -573,15 +578,6 @@ module API
     class Issue < IssueBasic
       include ::API::Helpers::RelatedResourcesHelpers
 
-      expose :labels do |issue, options|
-        # Avoids an N+1 query since labels are preloaded
-        if options[:with_labels_data]
-          ::API::Entities::LabelBasic.represent(issue.labels.sort_by(&:title))
-        else
-          issue.labels.map(&:title).sort
-        end
-      end
-
       expose(:has_tasks) do |issue, _|
         !issue.task_list_items.empty?
       end
diff --git a/lib/api/helpers/issues_helpers.rb b/lib/api/helpers/issues_helpers.rb
index fb791691069..fc66cec5341 100644
--- a/lib/api/helpers/issues_helpers.rb
+++ b/lib/api/helpers/issues_helpers.rb
@@ -31,12 +31,10 @@ module API
       end
 
       def find_issues(args = {})
-        # rubocop: disable CodeReuse/ActiveRecord
         finder = issue_finder(args)
         issues = finder.execute.with_api_entity_associations
 
-        issues.reorder(order_options_with_tie_breaker)
-        # rubocop: enable CodeReuse/ActiveRecord
+        issues.reorder(order_options_with_tie_breaker) # rubocop: disable CodeReuse/ActiveRecord
       end
 
       def issues_statistics(args = {})
diff --git a/lib/api/issues.rb b/lib/api/issues.rb
index 9fd2d959c22..0b4da01f3c8 100644
--- a/lib/api/issues.rb
+++ b/lib/api/issues.rb
@@ -51,7 +51,7 @@ module API
       end
 
       params :issues_params do
-        optional :with_labels_data, type: Boolean, desc: 'Return more label data than just lable title', default: false
+        optional :with_labels_details, type: Boolean, desc: 'Return more label data than just lable title', default: false
         optional :state, type: String, values: %w[opened closed all], default: 'all',
                  desc: 'Return opened, closed, or all issues'
         optional :order_by, type: String, values: %w[created_at updated_at], default: 'created_at',
@@ -80,15 +80,13 @@ module API
     desc "Get currently authenticated user's issues statistics"
     params do
       use :issues_stats_params
-      optional :scope, type: String, values: %w[created-by-me assigned-to-me created_by_me assigned_to_me all], default: 'created_by_me',
+      optional :scope, type: String, values: %w[created_by_me assigned_to_me all], default: 'created_by_me',
                        desc: 'Return issues for the given scope: `created_by_me`, `assigned_to_me` or `all`'
     end
     get '/issues_statistics' do
       authenticate! unless params[:scope] == 'all'
 
-      stats = issues_statistics
-
-      present stats, with: Grape::Presenters::Presenter
+      present issues_statistics, with: Grape::Presenters::Presenter
     end
 
     resource :issues do
@@ -106,7 +104,7 @@ module API
 
         options = {
           with: Entities::Issue,
-          with_labels_data: declared_params[:with_labels_data],
+          with_labels_details: declared_params[:with_labels_details],
           current_user: current_user,
           issuable_metadata: issuable_meta_data(issues, 'Issue')
         }
@@ -132,7 +130,7 @@ module API
 
         options = {
           with: Entities::Issue,
-          with_labels_data: declared_params[:with_labels_data],
+          with_labels_details: declared_params[:with_labels_details],
           current_user: current_user,
           issuable_metadata: issuable_meta_data(issues, 'Issue')
         }
@@ -147,9 +145,7 @@ module API
       get ":id/issues_statistics" do
         group = find_group!(params[:id])
 
-        stats = issues_statistics(group_id: group.id, include_subgroups: true)
-
-        present stats, with: Grape::Presenters::Presenter
+        present issues_statistics(group_id: group.id, include_subgroups: true), with: Grape::Presenters::Presenter
       end
     end
 
@@ -172,7 +168,7 @@ module API
 
         options = {
           with: Entities::Issue,
-          with_labels_data: declared_params[:with_labels_data],
+          with_labels_details: declared_params[:with_labels_details],
           current_user: current_user,
           project: user_project,
           issuable_metadata: issuable_meta_data(issues, 'Issue')
@@ -188,9 +184,7 @@ module API
       get ":id/issues_statistics" do
         project = find_project!(params[:id])
 
-        stats = issues_statistics(project_id: project.id)
-
-        present stats, with: Grape::Presenters::Presenter
+        present issues_statistics(project_id: project.id), with: Grape::Presenters::Presenter
       end
 
       desc 'Get a single project issue' do
diff --git a/lib/api/validations/check_assignees_count.rb b/lib/api/validations/check_assignees_count.rb
index e19c88e97b1..836ec936b31 100644
--- a/lib/api/validations/check_assignees_count.rb
+++ b/lib/api/validations/check_assignees_count.rb
@@ -6,12 +6,8 @@ module API
       def self.coerce
         lambda do |value|
           case value
-          when String
-            [value]
-          when Array
-            value
-          when CheckAssigneesCount
-            value
+          when String, Array
+            Array.wrap(value)
           else
             []
           end
@@ -19,11 +15,11 @@ module API
       end
 
       def validate_param!(attr_name, params)
-        unless param_allowed?(attr_name, params)
-          raise Grape::Exceptions::Validation,
-                params: [@scope.full_name(attr_name)],
-                message: "allows one value, but found #{params[attr_name].size}: #{params[attr_name].join(", ")}"
-        end
+        return if param_allowed?(attr_name, params)
+
+        raise Grape::Exceptions::Validation,
+              params: [@scope.full_name(attr_name)],
+              message: "allows one value, but found #{params[attr_name].size}: #{params[attr_name].join(", ")}"
       end
 
       private
diff --git a/spec/requests/api/issues/issues_spec.rb b/spec/requests/api/issues/issues_spec.rb
index 24c53d9c68f..9b9cc778fb3 100644
--- a/spec/requests/api/issues/issues_spec.rb
+++ b/spec/requests/api/issues/issues_spec.rb
@@ -122,25 +122,25 @@ describe API::Issues do
         expect_paginated_array_response([issue.id, closed_issue.id])
       end
 
-      it 'returns authentication error without any scope' do
-        get api('/issues_statistics')
+      context 'issues_statistics' do
+        it 'returns authentication error without any scope' do
+          get api('/issues_statistics')
 
-        expect(response).to have_http_status(401)
-      end
+          expect(response).to have_http_status(401)
+        end
 
-      it 'returns authentication error when scope is assigned-to-me' do
-        get api('/issues_statistics'), params: { scope: 'assigned-to-me' }
+        it 'returns authentication error when scope is assigned_to_me' do
+          get api('/issues_statistics'), params: { scope: 'assigned_to_me' }
 
-        expect(response).to have_http_status(401)
-      end
+          expect(response).to have_http_status(401)
+        end
 
-      it 'returns authentication error when scope is created-by-me' do
-        get api('/issues_statistics'), params: { scope: 'created-by-me' }
+        it 'returns authentication error when scope is created_by_me' do
+          get api('/issues_statistics'), params: { scope: 'created_by_me' }
 
-        expect(response).to have_http_status(401)
-      end
+          expect(response).to have_http_status(401)
+        end
 
-      context 'issues_statistics' do
         context 'no state is treated as all state' do
           let(:params) { {} }
           let(:counts) { { all: 2, closed: 1, opened: 1 } }
@@ -386,6 +386,31 @@ describe API::Issues do
       end
 
       context 'filter by labels or label_name param' do
+        context 'N+1' do
+          let(:label_b) { create(:label, title: 'foo', project: project) }
+          let(:label_c) { create(:label, title: 'bar', project: project) }
+
+          before do
+            create(:label_link, label: label_b, target: issue)
+            create(:label_link, label: label_c, target: issue)
+          end
+          it 'tests N+1' do
+            control = ActiveRecord::QueryRecorder.new do
+              get api('/issues', user), params: { labels: [label.title, label_b.title, label_c.title] }
+            end
+
+            label_d = create(:label, title: 'dar', project: project)
+            label_e = create(:label, title: 'ear', project: project)
+            create(:label_link, label: label_d, target: issue)
+            create(:label_link, label: label_e, target: issue)
+
+            expect do
+              get api('/issues', user), params: { labels: [label.title, label_b.title, label_c.title] }
+            end.not_to exceed_query_limit(control)
+            expect(issue.labels.count).to eq(5)
+          end
+        end
+
         it 'returns an array of labeled issues' do
           get api('/issues', user), params: { labels: label.title }
 
diff --git a/spec/support/shared_examples/requests/api/issues_shared_example_spec.rb b/spec/support/shared_examples/requests/api/issues_shared_example_spec.rb
index d1c8e2208a3..1133e95e44e 100644
--- a/spec/support/shared_examples/requests/api/issues_shared_example_spec.rb
+++ b/spec/support/shared_examples/requests/api/issues_shared_example_spec.rb
@@ -28,15 +28,15 @@ shared_examples 'labeled issues with labels and label_name params' do
     it_behaves_like 'returns label names'
   end
 
-  context 'when with_labels_data provided' do
+  context 'when with_labels_details provided' do
     context 'array of labeled issues when all labels match' do
-      let(:params) { { labels: "#{label.title},#{label_b.title},#{label_c.title}", with_labels_data: true } }
+      let(:params) { { labels: "#{label.title},#{label_b.title},#{label_c.title}", with_labels_details: true } }
 
       it_behaves_like 'returns basic label entity'
     end
 
     context 'array of labeled issues when all labels match with labels param as array' do
-      let(:params) { { labels: [label.title, label_b.title, label_c.title], with_labels_data: true } }
+      let(:params) { { labels: [label.title, label_b.title, label_c.title], with_labels_details: true } }
 
       it_behaves_like 'returns basic label entity'
     end