Add specs for `TokenAuthenticatable` concern

spec/models/concerns/token_authenticatable_spec.rb

+require 'spec_helper'
+
+shared_examples 'TokenAuthenticatable' do
+  describe 'dynamically defined methods' do
+    it { expect(described_class).to be_private_method_defined(:generate_token_for) }
+    it { expect(described_class).to respond_to("find_by_#{token_field}") }
+    it { is_expected.to respond_to("ensure_#{token_field}") }
+    it { is_expected.to respond_to("reset_#{token_field}!") }
+  end
+end
+
+describe User, 'TokenAuthenticatable' do
+  let(:token_field) { :authentication_token }
+  it_behaves_like 'TokenAuthenticatable'
+
+  describe 'ensured authentication token' do
+    subject { create(:user).send(token_field) }
+    it { is_expected.to be_a String }
+  end
+end
+
+describe ApplicationSetting, 'TokenAuthenticatable' do
+  let(:token_field) { :runners_registration_token }
+  it_behaves_like 'TokenAuthenticatable'
+
+  describe 'generating new token' do
+    subject { described_class.new }
+    let(:token) { subject.send(token_field) }
+
+    context 'token is not generated yet' do
+      it { expect(token).to be nil }
+    end
+
+    context 'token is generated' do
+      before { subject.send("reset_#{token_field}!") }
+      it { expect(token).to be_a String }
+    end
+  end
+
+  describe 'multiple token fields' do
+    before do
+      described_class.send(:add_authentication_token_field, :yet_another_token)
+    end
+
+    describe '.token_fields' do
+      subject { described_class.authentication_token_fields }
+      it { is_expected.to include(:runners_registration_token, :yet_another_token) }
+    end
+  end
+end