Add api endpoint to retrieve resource weight events

Also extract base class for ResourceEventsFinder and update specs.

doc/api/resource_weight_events.md

+---
+stage: Plan
+group: Project Management
+info: To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/engineering/ux/technical-writing/#designated-technical-writers
+---
+
+# Resource weight events API
+
+Resource weight events keep track of what happens to GitLab [issues](../user/project/issues/).
+
+Use them to track which weight was set, who did it, and when it happened.
+
+## Issues
+
+### List project issue weight events
+
+Gets a list of all weight events for a single issue.
+
+```plaintext
+GET /projects/:id/issues/:issue_iid/resource_weight_events
+```
+
+| Attribute   | Type           | Required | Description                                                                     |
+| ----------- | -------------- | -------- | ------------------------------------------------------------------------------- |
+| `id`        | integer/string | yes      | The ID or [URL-encoded path of the project](README.md#namespaced-path-encoding) |
+| `issue_iid` | integer        | yes      | The IID of an issue                                                             |
+
+Example request:
+
+```shell
+curl --header "PRIVATE-TOKEN: <your_access_token>" "https://gitlab.example.com/api/v4/projects/5/issues/11/resource_weight_events"
+```
+
+Example response:
+
+```json
+[
+  {
+    "id": 142,
+    "user": {
+      "id": 1,
+      "name": "Administrator",
+      "username": "root",
+      "state": "active",
+      "avatar_url": "https://www.gravatar.com/avatar/e64c7d89f26bd1972efa854d13d7dd61?s=80&d=identicon",
+      "web_url": "http://gitlab.example.com/root"
+    },
+    "created_at": "2018-08-20T13:38:20.077Z",
+    "issue_id": 253,
+    "weight": 3
+  },
+  {
+    "id": 143,
+    "user": {
+      "id": 1,
+      "name": "Administrator",
+      "username": "root",
+      "state": "active",
+      "avatar_url": "https://www.gravatar.com/avatar/e64c7d89f26bd1972efa854d13d7dd61?s=80&d=identicon",
+      "web_url": "http://gitlab.example.com/root"
+    },
+    "created_at": "2018-08-21T14:38:20.077Z",
+    "issue_id": 253,
+    "weight": 2
+  }
+]
+```
+
+### Get single issue weight event
+
+Returns a single weight event for a specific project issue
+
+```plaintext
+GET /projects/:id/issues/:issue_iid/resource_weight_events/:resource_weight_event_id
+```
+
+Parameters:
+
+| Attribute                     | Type           | Required | Description                                                                     |
+| ----------------------------- | -------------- | -------- | ------------------------------------------------------------------------------- |
+| `id`                          | integer/string | yes      | The ID or [URL-encoded path](README.md#namespaced-path-encoding) of the project |
+| `issue_iid`                   | integer        | yes      | The IID of an issue                                                             |
+| `resource_weight_event_id`    | integer        | yes      | The ID of a weight event                                                     |
+
+Example request:
+
+```shell
+curl --header "PRIVATE-TOKEN: <your_access_token>" "https://gitlab.example.com/api/v4/projects/5/issues/11/resource_weight_events/143"
+```
+
+Example response:
+
+```json
+{
+"id": 143,
+"user": {
+  "id": 1,
+  "name": "Administrator",
+  "username": "root",
+  "state": "active",
+  "avatar_url": "https://www.gravatar.com/avatar/e64c7d89f26bd1972efa854d13d7dd61?s=80&d=identicon",
+  "web_url": "http://gitlab.example.com/root"
+},
+"created_at": "2018-08-21T14:38:20.077Z",
+"issue_id": 253,
+"weight": 2
+}
+```

ee/changelogs/unreleased/add-resource-weight-events-api-endpoint-pd.yml

+---
+title: Add api endpoint to retrieve resource weight events
+merge_request: 32542
+author:
+type: added

ee/lib/api/resource_weight_events.rb

+# frozen_string_literal: true
+
+module API
+  class ResourceWeightEvents < Grape::API
+    include PaginationParams
+    helpers ::API::Helpers::NotesHelpers
+
+    before { authenticate! }
+
+    params do
+      requires :id, type: String, desc: "The ID of a project"
+    end
+    resource :projects, requirements: API::NAMESPACE_OR_PROJECT_REQUIREMENTS do
+      desc "Get a list of issue resource weight events" do
+        success EE::API::Entities::ResourceWeightEvent
+      end
+      params do
+        requires :eventable_id, types: [Integer, String], desc: 'The ID of the eventable'
+        use :pagination
+      end
+
+      get ":id/issues/:eventable_id/resource_weight_events" do
+        eventable = find_noteable(Issue, params[:eventable_id])
+
+        events = if Ability.allowed?(current_user, :read_issue, eventable)
+                   eventable.resource_weight_events
+                 else
+                   ResourceWeightEvent.none
+                 end
+
+        present paginate(events), with: EE::API::Entities::ResourceWeightEvent
+      end
+
+      desc "Get a single issue resource weight event" do
+        success EE::API::Entities::ResourceWeightEvent
+      end
+      params do
+        requires :event_id, type: String, desc: 'The ID of a resource weight event'
+        requires :eventable_id, types: [Integer, String], desc: 'The ID of the eventable'
+      end
+      get ":id/issues/:eventable_id/resource_weight_events/:event_id" do
+        eventable = find_noteable(Issue, params[:eventable_id])
+
+        event = eventable.resource_weight_events.find(params[:event_id])
+
+        not_found!('ResourceWeightEvent') unless can?(current_user, :read_issue, event.issue)
+
+        present event, with: EE::API::Entities::ResourceWeightEvent
+      end
+    end
+  end
+end

ee/lib/ee/api/api.rb

@@ -59,6 +59,7 @@ module EE
         mount ::API::Analytics::CodeReviewAnalytics
         mount ::API::Analytics::GroupActivityAnalytics
         mount ::API::ProtectedEnvironments
+        mount ::API::ResourceWeightEvents
 
         version 'v3', using: :path do
           # Although the following endpoints are kept behind V3 namespace,

ee/lib/ee/api/entities/resource_weight_event.rb

+# frozen_string_literal: true
+
+module EE
+  module API
+    module Entities
+      class ResourceWeightEvent < Grape::Entity
+        expose :id
+        expose :user, using: ::API::Entities::UserBasic
+        expose :created_at
+        expose :issue_id
+        expose :weight
+      end
+    end
+  end
+end

ee/spec/requests/api/resource_weight_events_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe ::API::ResourceWeightEvents do
+  let_it_be(:user) { create(:user) }
+  let_it_be(:project, reload: true) { create(:project, :public, namespace: user.namespace) }
+  let_it_be(:issue) { create(:issue, project: project, author: user) }
+
+  before do
+    project.add_developer(user)
+  end
+
+  describe "GET /projects/:id/issues/:noteable_id/resource_weight_events" do
+    let!(:event) { create_event }
+
+    it "returns an array of resource weight events" do
+      get api("/projects/#{project.id}/issues/#{issue.iid}/resource_weight_events", user)
+
+      expect(response).to have_gitlab_http_status(:ok)
+      expect(response).to include_pagination_headers
+      expect(json_response).to be_an Array
+      expect(json_response.first['id']).to eq(event.id)
+    end
+
+    it "returns a 404 error when issue id not found" do
+      get api("/projects/#{project.id}/issues/#{non_existing_record_id}/resource_weight_events", user)
+
+      expect(response).to have_gitlab_http_status(:not_found)
+    end
+
+    it "returns 404 when not authorized" do
+      project.update!(visibility_level: Gitlab::VisibilityLevel::PRIVATE)
+      private_user = create(:user)
+
+      get api("/projects/#{project.id}/issues/#{issue.iid}/resource_weight_events", private_user)
+
+      expect(response).to have_gitlab_http_status(:not_found)
+    end
+  end
+
+  describe "GET /projects/:id/issues/:noteable_id/resource_weight_events/:event_id" do
+    let!(:event) { create_event }
+
+    it "returns a resource weight event by id" do
+      get api("/projects/#{project.id}/issues/#{issue.iid}/resource_weight_events/#{event.id}", user)
+
+      expect(response).to have_gitlab_http_status(:ok)
+      expect(json_response['id']).to eq(event.id)
+    end
+
+    it "returns 404 when not authorized" do
+      project.update!(visibility_level: Gitlab::VisibilityLevel::PRIVATE)
+      private_user = create(:user)
+
+      get api("/projects/#{project.id}/issues/#{issue.iid}/resource_weight_events/#{event.id}", private_user)
+
+      expect(response).to have_gitlab_http_status(:not_found)
+    end
+
+    it "returns a 404 error if resource weight event not found" do
+      get api("/projects/#{project.id}/issues/#{issue.iid}/resource_weight_events/#{non_existing_record_id}", user)
+
+      expect(response).to have_gitlab_http_status(:not_found)
+    end
+  end
+
+  describe 'pagination' do
+    let!(:event1) { create_event }
+    let!(:event2) { create_event }
+
+    # https://gitlab.com/gitlab-org/gitlab/-/issues/220192
+    it "returns the second page" do
+      get api("/projects/#{project.id}/issues/#{issue.iid}/resource_weight_events?page=2&per_page=1", user)
+
+      expect(response).to have_gitlab_http_status(:ok)
+      expect(json_response.count).to eq(1)
+      expect(json_response.first['id']).to eq(event2.id)
+    end
+  end
+
+  def create_event
+    create(:resource_weight_event, issue: issue, weight: 2)
+  end
+end