move token validity to trusted_device_token

spec/models/trusted_device_token_spec.rb

@@ -0,0 +1,15 @@
+RSpec.describe TrustedDeviceToken, type: :model do
+  describe '#token_valid?' do
+    let(:token) { TrustedDeviceToken.create }
+
+    context 'when the token is create after login_token_validity' do
+      it { expect(token.token_valid?).to be true }
+    end
+
+    context 'when the token is create before login_token_validity' do
+      before { token.update(created_at: (TrustedDeviceToken::LOGIN_TOKEN_VALIDITY + 1.minute).ago) }
+
+      it { expect(token.token_valid?).to be false }
+    end
+  end
+end