Expose whether current user can push into a branch on branches API

changelogs/unreleased/dm-branch-api-can-push.yml

+---
+title: Expose whether current user can push into a branch on branches API
+merge_request:
+author:
+type: added

doc/api/branches.md

@@ -29,6 +29,7 @@ Example response:
     "protected": true,
     "developers_can_push": false,
     "developers_can_merge": false,
+    "can_push": true,
     "commit": {
       "author_email": "john@example.com",
       "author_name": "John Smith",
@@ -76,6 +77,7 @@ Example response:
   "protected": true,
   "developers_can_push": false,
   "developers_can_merge": false,
+  "can_push": true,
   "commit": {
     "author_email": "john@example.com",
     "author_name": "John Smith",
@@ -140,7 +142,8 @@ Example response:
   "merged": false,
   "protected": true,
   "developers_can_push": true,
-  "developers_can_merge": true
+  "developers_can_merge": true,
+  "can_push": true
 }
 ```
 
@@ -188,7 +191,8 @@ Example response:
   "merged": false,
   "protected": false,
   "developers_can_push": false,
-  "developers_can_merge": false
+  "developers_can_merge": false,
+  "can_push": true
 }
 ```
 
@@ -231,7 +235,8 @@ Example response:
   "merged": false,
   "protected": false,
   "developers_can_push": false,
-  "developers_can_merge": false
+  "developers_can_merge": false,
+  "can_push": true
 }
 ```
 

lib/api/entities.rb

@@ -349,6 +349,10 @@ module API
       expose :developers_can_merge do |repo_branch, options|
         options[:project].protected_branches.developers_can?(:merge, repo_branch.name)
       end
+
+      expose :can_push do |repo_branch, options|
+        Gitlab::UserAccess.new(options[:current_user], project: options[:project]).can_push_to_branch?(repo_branch.name)
+      end
     end
 
     class TreeObject < Grape::Entity

spec/fixtures/api/schemas/public_api/v4/branch.json

@@ -14,7 +14,8 @@
     "merged": { "type": "boolean" },
     "protected": { "type": "boolean" },
     "developers_can_push": { "type": "boolean" },
-    "developers_can_merge": { "type": "boolean" }
+    "developers_can_merge": { "type": "boolean" },
+    "can_push": { "type": "boolean" }
   },
   "additionalProperties": false
 }