Move the check to Pipeline.allowed_to_create?

So that we could use it for the schedule before
trying to use CreatePipelineService

app/models/ci/pipeline.rb

@@ -162,6 +162,20 @@ module Ci
       where.not(duration: nil).sum(:duration)
     end
 
+    def self.allowed_to_create?(user, project, ref)
+      repo = project.repository
+      access = Gitlab::UserAccess.new(user, project: project)
+
+      Ability.allowed?(user, :create_pipeline, project) &&
+        if repo.ref_exists?("#{Gitlab::Git::BRANCH_REF_PREFIX}#{ref}")
+          access.can_merge_to_branch?(ref)
+        elsif repo.ref_exists?("#{Gitlab::Git::TAG_REF_PREFIX}#{ref}")
+          access.can_create_tag?(ref)
+        else
+          false
+        end
+    end
+
     def stage(name)
       stage = Ci::Stage.new(self, name: name)
       stage unless stage.statuses_count.zero?

app/models/ci/pipeline_schedule.rb

@@ -37,7 +37,7 @@ module Ci
     end
 
     def runnable_by_owner?
-      Ability.allowed?(owner, :create_pipeline, project)
+      Ci::Pipeline.allowed_to_create?(owner, project, ref)
     end
 
     def set_next_run_at

app/services/ci/create_pipeline_service.rb

@@ -27,10 +27,8 @@ module Ci
         return error('Reference not found')
       end
 
-      if tag?
-        return error("#{ref} is protected") unless access.can_create_tag?(ref)
-      else
-        return error("#{ref} is protected") unless access.can_merge_to_branch?(ref)
+      unless Ci::Pipeline.allowed_to_create?(current_user, project, ref)
+        return error("Insufficient permissions for protected #{ref}")
       end
 
       unless commit
@@ -53,6 +51,12 @@ module Ci
         return error('No builds for this pipeline.')
       end
 
+      process!
+    end
+
+    private
+
+    def process!
       Ci::Pipeline.transaction do
         update_merge_requests_head_pipeline if pipeline.save
 
@@ -66,8 +70,6 @@ module Ci
       pipeline.tap(&:process!)
     end
 
-    private
-
     def update_merge_requests_head_pipeline
       return unless pipeline.latest?
 
@@ -100,10 +102,6 @@ module Ci
       @commit ||= project.commit(origin_sha || origin_ref)
     end
 
-    def access
-      @access ||= Gitlab::UserAccess.new(current_user, project: project)
-    end
-
     def sha
       commit.try(:id)
     end
@@ -121,11 +119,17 @@ module Ci
     end
 
     def branch?
-      project.repository.ref_exists?(Gitlab::Git::BRANCH_REF_PREFIX + ref)
+      return @is_branch if defined?(@is_branch)
+
+      @is_branch =
+        project.repository.ref_exists?(Gitlab::Git::BRANCH_REF_PREFIX + ref)
     end
 
     def tag?
-      project.repository.ref_exists?(Gitlab::Git::TAG_REF_PREFIX + ref)
+      return @is_tag if defined?(@is_tag)
+
+      @is_tag =
+        project.repository.ref_exists?(Gitlab::Git::TAG_REF_PREFIX + ref)
     end
 
     def ref

spec/models/ci/pipeline_spec.rb

@@ -28,6 +28,103 @@ describe Ci::Pipeline, models: true do
   it { is_expected.to respond_to :git_author_email }
   it { is_expected.to respond_to :short_sha }
 
+  describe '.allowed_to_create?' do
+    let(:user) { create(:user) }
+    let(:project) { create(:project, :repository) }
+    let(:ref) { 'master' }
+
+    subject { described_class.allowed_to_create?(user, project, ref) }
+
+    context 'when user is a developer' do
+      before do
+        project.add_developer(user)
+      end
+
+      it { is_expected.to be_truthy }
+
+      context 'when the branch is protected' do
+        let!(:protected_branch) do
+          create(:protected_branch, project: project, name: ref)
+        end
+
+        it { is_expected.to be_falsey }
+
+        context 'when developers are allowed to merge' do
+          let!(:protected_branch) do
+            create(:protected_branch,
+                   :developers_can_merge,
+                   project: project,
+                   name: ref)
+          end
+
+          it { is_expected.to be_truthy }
+        end
+      end
+
+      context 'when the tag is protected' do
+        let(:ref) { 'v1.0.0' }
+
+        let!(:protected_tag) do
+          create(:protected_tag, project: project, name: ref)
+        end
+
+        it { is_expected.to be_falsey }
+
+        context 'when developers are allowed to create the tag' do
+          let!(:protected_tag) do
+            create(:protected_tag,
+                   :developers_can_create,
+                   project: project,
+                   name: ref)
+          end
+
+          it { is_expected.to be_truthy }
+        end
+      end
+    end
+
+    context 'when user is a master' do
+      before do
+        project.add_master(user)
+      end
+
+      it { is_expected.to be_truthy }
+
+      context 'when the branch is protected' do
+        let!(:protected_branch) do
+          create(:protected_branch, project: project, name: ref)
+        end
+
+        it { is_expected.to be_truthy }
+      end
+
+      context 'when the tag is protected' do
+        let(:ref) { 'v1.0.0' }
+
+        let!(:protected_tag) do
+          create(:protected_tag, project: project, name: ref)
+        end
+
+        it { is_expected.to be_truthy }
+
+        context 'when no one can create the tag' do
+          let!(:protected_tag) do
+            create(:protected_tag,
+                   :no_one_can_create,
+                   project: project,
+                   name: ref)
+          end
+
+          it { is_expected.to be_falsey }
+        end
+      end
+    end
+
+    context 'when owner cannot create pipeline' do
+      it { is_expected.to be_falsey }
+    end
+  end
+
   describe '#source' do
     context 'when creating new pipeline' do
       let(:pipeline) do