Validate configuration

lib/hotsheet.rb

@@ -15,9 +15,8 @@ def configuration
       @configuration ||= Configuration.new
     end
 
-    def configure
-      @configuration = Configuration.new
-      yield configuration
+    def configure(&block)
+      @configuration = Configuration.new.tap(&block)
     end
 
     def models

lib/hotsheet/configuration.rb

@@ -10,14 +10,46 @@ def initialize
       self.models = {}
     end
 
-    def model(name, &block)
-      model_config = ModelConfig.new
-      yield model_config if block
+    def model(name)
+      model_config = ModelConfig.new(name).tap do |config|
+        yield(config)
+        Rails.application.config.to_prepare { config.validate! }
+      end
       models[name.to_s] = model_config
     end
 
     class ModelConfig
-      attr_accessor :included_attributes, :excluded_attributes
+      attr_accessor :included_attributes, :excluded_attributes, :model_name
+
+      def initialize(model_name)
+        @model_name = model_name
+        @included_attributes = []
+        @excluded_attributes = []
+      end
+
+      def validate!
+        ensure_only_one_attribute_set
+        validate_attribute_existence
+      end
+
+      private
+
+      def ensure_only_one_attribute_set
+        return unless included_attributes.any? && excluded_attributes.any?
+
+        raise "Can only specify either included or excluded attributes for '#{model_name}'"
+      end
+
+      def validate_attribute_existence
+        model_class = model_name.to_s.constantize
+        all_attributes = model_class.column_names
+
+        (included_attributes + excluded_attributes).each do |attr|
+          unless all_attributes.include?(attr.to_s)
+            raise "Attribute '#{attr}' doesn't exist on model '#{model_name}'"
+          end
+        end
+      end
     end
   end
 end

spec/lib/configuration_spec.rb

@@ -6,21 +6,20 @@
   subject(:config) { Hotsheet.configuration }
 
   context "without model configuration" do
-    before { Hotsheet.configure {} } # rubocop:disable Lint/EmptyBlock
+    before { Hotsheet.configure {} } # reset configuration
 
     it "does NOT have any configured model" do
       expect(config.models).to eq({})
     end
   end
 
-  context "with a model configuration" do
+  context "with a valid model configuration" do
     let(:model_config) { config.models["Author"] }
 
     before do
       Hotsheet.configure do |config|
         config.model :Author do |model|
           model.included_attributes = %i[name birthdate]
-          model.excluded_attributes = %i[created_at]
         end
       end
     end
@@ -30,10 +29,84 @@
       expect(config.models["Author"]).to be_a Hotsheet::Configuration::ModelConfig
     end
 
-    it "has included and excluded attributes" do
+    it "has included attributes set correctly" do
       expect(model_config).to be_a Hotsheet::Configuration::ModelConfig
       expect(model_config.included_attributes).to eq %i[name birthdate]
-      expect(model_config.excluded_attributes).to eq %i[created_at]
+    end
+  end
+
+  describe "Hotsheet::Configuration::ModelConfig" do
+    subject(:model_config) { Hotsheet::Configuration::ModelConfig.new("Author") }
+
+    let(:model_class) do
+      Class.new do
+        def self.name
+          "Author"
+        end
+
+        def self.column_names
+          %w[id name birthdate created_at updated_at]
+        end
+      end
+    end
+
+    before do
+      stub_const("Author", model_class)
+    end
+
+    context "when only included attributes are specified" do
+      before { model_config.included_attributes = %i[name birthdate] }
+
+      it "validates without errors" do
+        expect { model_config.validate! }.not_to raise_error
+      end
+    end
+
+    context "when only excluded attributes are specified" do
+      before { model_config.excluded_attributes = %i[created_at updated_at] }
+
+      it "validates without errors" do
+        expect { model_config.validate! }.not_to raise_error
+      end
+    end
+
+    context "when both included and excluded attributes are specified" do
+      before do
+        model_config.included_attributes = %i[name birthdate]
+        model_config.excluded_attributes = %i[created_at]
+      end
+
+      it "raises an error" do
+        expect do
+          model_config.validate!
+        end.to raise_error("Can only specify either included or excluded attributes for 'Author'")
+      end
+    end
+
+    context "when included attributes contain a non-existent attribute" do
+      before { model_config.included_attributes = %i[name non_existent_attribute] }
+
+      it "raises an error indicating the attribute does not exist" do
+        expect do
+          model_config.validate!
+        end.to raise_error("Attribute 'non_existent_attribute' doesn't exist on model 'Author'")
+      end
+    end
+
+    context "when excluded attributes contain a non-existent attribute" do
+      before { model_config.excluded_attributes = %i[non_existent_attribute] }
+
+      it "raises an error indicating the attribute does not exist" do
+        expect do
+          model_config.validate!
+        end.to raise_error("Attribute 'non_existent_attribute' doesn't exist on model 'Author'")
+      end
+    end
+
+    context "when no included or excluded attributes are specified" do
+      it "validates without errors" do
+        expect { model_config.validate! }.not_to raise_error
+      end
     end
   end
 end