ActiveModel::Lint for rspec

active_model_lint.rb

# Provides an rspec version https://github.com/rails/rails/blob/master/activemodel/lib/active_model/lint.rb
# Approaches like https://gist.github.com/msgehard/910773 do not seem to work with
# current versions of minitest.
#
# Usage:
# 1. Put file in spec/support
# 2. Add it_behaves_like 'ActiveModel' in your spec file
shared_examples_for 'ActiveModel' do

  let(:model) { subject }

  describe '#to_key' do
    it 'returns nil if not persisted' do
      expect(model).to respond_to :to_key

      model.stub(:persisted?).and_return(false)
      expect(model.to_key).to be_nil
    end
  end

  describe '#to_param' do
    it 'returns nil if not persisted' do
      expect(model).to respond_to :to_param

      model.stub(:persisted?).and_return(false)
      expect(model.to_param).to be_nil
    end
  end

  describe '#to_partial_path' do
    it 'returns a string' do
      expect(model.to_partial_path).to be_kind_of String
    end
  end

  describe '#persisted?' do
    it 'returns a boolean' do
      expect(model.persisted?).to satisfy { |b| [true, false].include?(b) }
    end
  end

  describe '.model_name' do
    it 'responds to to_str' do
      expect(model.class.model_name).to respond_to :to_str
    end
    
    [:human, :singular, :plural].each do |o|
      it "#{o} responds to to_str" do
        expect(model.class.model_name.send(o)).to respond_to :to_str
      end
    end
  end

  describe '#errors' do
    it 'returns a hash with arrays' do
      expect(model.errors[:hello]).to be_a Array
    end
  end

end