Merge branch 'add_commit_stats' into 'master'

Add commit stats

## What does this MR do?
When getting commit by SHA in api it returns commit stats

## Are there points in the code the reviewer needs to double check?
Not sure about test I added do we need separate test or we can just shove stats assertion in test above

## Why was this MR needed?
So api users/clients can get statistics on single commit

## What are the relevant issue numbers?
#20307 

## Screenshots (if relevant)

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [x] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [x] API support added
- Tests
  - [x] Added for this feature/bug
  - [x] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !5517

CHANGELOG

@@ -22,6 +22,7 @@ v 8.11.0 (unreleased)
   - Add the `sprockets-es6` gem
   - Multiple trigger variables show in separate lines (Katarzyna Kobierska Ula Budziszewska)
   - Profile requests when a header is passed
+  - Add commit stats in commit api. !5517 (dixpac)
   - Make error pages responsive (Takuya Noguchi)
   - Change requests_profiles resource constraint to catch virtually any file
 

doc/api/commits.md

@@ -81,6 +81,11 @@ Example response:
   "parent_ids": [
     "ae1d9fb46aa2b07ee9836d49862ec4e2c46fbbba"
   ],
+  "stats": {
+    "additions": 15,
+    "deletions": 10,
+    "total": 25
+  },
   "status": "running"
 }
 ```

lib/api/entities.rb

@@ -149,8 +149,13 @@ module API
       expose :safe_message, as: :message
     end
 
+    class RepoCommitStats < Grape::Entity
+      expose :additions, :deletions, :total
+    end
+
     class RepoCommitDetail < RepoCommit
       expose :parent_ids, :committed_date, :authored_date
+      expose :stats, using: Entities::RepoCommitStats
       expose :status
     end
 

spec/requests/api/commits_spec.rb

@@ -73,9 +73,13 @@ describe API::API, api: true  do
     context "authorized user" do
       it "should return a commit by sha" do
         get api("/projects/#{project.id}/repository/commits/#{project.repository.commit.id}", user)
+
         expect(response).to have_http_status(200)
         expect(json_response['id']).to eq(project.repository.commit.id)
         expect(json_response['title']).to eq(project.repository.commit.title)
+        expect(json_response['stats']['additions']).to eq(project.repository.commit.stats.additions)
+        expect(json_response['stats']['deletions']).to eq(project.repository.commit.stats.deletions)
+        expect(json_response['stats']['total']).to eq(project.repository.commit.stats.total)
       end
 
       it "should return a 404 error if not found" do