Update existing protected branch

This sets the option to require code owner approval on an existing
protected branch instead of deleting it and creating it again.

qa/qa/resource/protected_branch.rb

@@ -61,6 +61,8 @@ module QA
       end
 
       def fabricate_via_api!
+        resource_web_url(api_get)
+      rescue ResourceNotFoundError
         populate_new_branch_if_required
 
         super
@@ -75,7 +77,11 @@ module QA
       end
 
       def api_delete_path
-        "/projects/#{project.id}/protected_branches/#{branch_name}"
+        api_get_path
+      end
+
+      def api_put_path
+        api_get_path
       end
 
       def api_post_path
@@ -107,6 +113,16 @@ module QA
         # this particular resource does not expose a web_url property
       end
 
+      def set_require_code_owner_approval(require = true)
+        response = patch(Runtime::API::Request.new(api_client, api_put_path).url, { code_owner_approval_required: require })
+        return if response.code == HTTP_STATUS_OK
+
+        raise(
+          ResourceUpdateFailedError,
+          "Could not update code_owner_approval_required to #{require}. Request returned (#{response.code}): `#{response}`."
+        )
+      end
+
       class Roles
         NO_ONE = { description: 'No one', access_level: 0 }.freeze
         DEVS_AND_MAINTAINERS = { description: 'Developers + Maintainers', access_level: 30 }.freeze

qa/qa/support/api.rb

@@ -44,6 +44,18 @@ module QA
         end
       end
 
+      def patch(url, payload = nil)
+        with_retry_on_too_many_requests do
+          RestClient::Request.execute(
+            method: :patch,
+            url: url,
+            payload: payload,
+            verify_ssl: false)
+        rescue RestClient::ExceptionWithResponse => e
+          return_response_or_raise(e)
+        end
+      end
+
       def put(url, payload = nil)
         with_retry_on_too_many_requests do
           RestClient::Request.execute(

qa/spec/support/shared_examples/merge_with_code_owner_shared_examples.rb

@@ -31,19 +31,13 @@ module QA
       end
 
       # Require approval from code owners on the default branch
-      # The default branch is already protected, and we can't update a protected branch via the API (yet)
-      # so we unprotect it first and then protect it again with the desired parameters
-      Resource::ProtectedBranch.unprotect_via_api! do |protected_branch|
-        protected_branch.project = project
-        protected_branch.branch_name = project.default_branch
-      end
-
-      Resource::ProtectedBranch.fabricate_via_api! do |protected_branch|
-        protected_branch.project = project
-        protected_branch.branch_name = project.default_branch
-        protected_branch.new_branch = false
-        protected_branch.require_code_owner_approval = true
+      protected_branch = Resource::ProtectedBranch.fabricate_via_api! do |branch|
+        branch.project = project
+        branch.branch_name = project.default_branch
+        branch.new_branch = false
+        branch.require_code_owner_approval = true
       end
+      protected_branch.set_require_code_owner_approval
 
       # Push a change to the file with a CODEOWNERS rule
       Resource::Repository::Push.fabricate! do |push|