Added error entities

ee/lib/ee/gitlab/scim/error.rb

+# frozen_string_literal: true
+
+module EE
+  module Gitlab
+    module Scim
+      class Error < EE::Gitlab::Scim::NotFound
+        def status
+          409
+        end
+      end
+    end
+  end
+end

ee/lib/ee/gitlab/scim/not_found.rb

+# frozen_string_literal: true
+
+module EE
+  module Gitlab
+    module Scim
+      class NotFound < Grape::Entity
+        expose :schemas
+        expose :detail, safe: true
+        expose :status
+
+        private
+
+        DEFAULT_SCHEMA = 'urn:ietf:params:scim:api:messages:2.0:Error'
+
+        def schemas
+          [DEFAULT_SCHEMA]
+        end
+
+        def status
+          404
+        end
+      end
+    end
+  end
+end

ee/spec/lib/gitlab/scim/error_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe ::EE::Gitlab::Scim::Error do
+  let(:params) { { detail: 'error' } }
+  let(:entity) do
+    described_class.new(params)
+  end
+
+  subject { entity.as_json }
+
+  it 'contains the schemas' do
+    expect(subject[:schemas]).not_to be_empty
+  end
+
+  it 'contains the detail' do
+    expect(subject[:detail]).to eq(params[:detail])
+  end
+
+  it 'contains the status' do
+    expect(subject[:status]).to eq(409)
+  end
+end

ee/spec/lib/gitlab/scim/not_found_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe ::EE::Gitlab::Scim::NotFound do
+  let(:entity) do
+    described_class.new({})
+  end
+
+  subject { entity.as_json }
+
+  it 'contains the schemas' do
+    expect(subject[:schemas]).not_to be_empty
+  end
+
+  it 'contains the detail' do
+    expect(subject[:detail]).to be_nil
+  end
+
+  it 'contains the status' do
+    expect(subject[:status]).to eq(404)
+  end
+end