Fix select with nil option (#120)

hanami-helpers.gemspec

@@ -23,7 +23,7 @@ Gem::Specification.new do |spec|
   spec.add_dependency 'hanami-utils', '~> 1.1'
 
   spec.add_development_dependency 'bundler',    '~> 1.6'
+  spec.add_development_dependency 'dry-struct', '~> 0.3'
   spec.add_development_dependency 'rake',       '~> 12'
   spec.add_development_dependency 'rspec',      '~> 3.7'
-  spec.add_development_dependency 'dry-struct', '~> 0.3'
 end

lib/hanami/helpers/form_helper/form_builder.rb

@@ -1206,8 +1206,9 @@ def select(name, values, attributes = {}) # rubocop:disable Metrics/AbcSize, Met
           super(attributes) do
             option(prompt) unless prompt.nil?
 
+            already_selected = nil
             values.each do |content, value|
-              if _select_option_selected?(value, selected, _value(name), attributes[:multiple])
+              if (attributes[:multiple] || !already_selected) && (already_selected = _select_option_selected?(value, selected, _value(name), attributes[:multiple]))
                 option(content, { value: value, selected: SELECTED }.merge(options))
               else
                 option(content, { value: value }.merge(options))
@@ -1547,8 +1548,10 @@ def _select_input_name(name, multiple)
         # rubocop:disable Metrics/CyclomaticComplexity
         # rubocop:disable Metrics/PerceivedComplexity
         def _select_option_selected?(value, selected, input_value, multiple)
-          value == selected || (multiple && (selected.is_a?(Array) && selected.include?(value))) ||
-            value.to_s == input_value.to_s || (multiple && (input_value.is_a?(Array) && input_value.include?(value)))
+          value == selected ||
+            (multiple && (selected.is_a?(Array) && selected.include?(value))) ||
+            value.to_s == input_value.to_s ||
+            (multiple && (input_value.is_a?(Array) && input_value.include?(value)))
         end
         # rubocop:enable Metrics/PerceivedComplexity
         # rubocop:enable Metrics/CyclomaticComplexity

spec/unit/hanami/helpers/form_helper_spec.rb

@@ -2427,6 +2427,34 @@
         expect(actual).to include(%(<select name="book[store]" id="book-store">\n<option value="it" selected="selected">Italy</option>\n<option value="us">United States</option>\n</select>))
       end
     end
+
+    describe 'with nil as a value' do
+      let(:option_values) { Hash['Italy' => 'it', 'United States' => 'us', 'N/A' => nil] }
+
+      it "sets nil option as selected by default" do
+        actual = view.form_for(:book, action) do
+          select :store, option_values
+        end.to_s
+
+        expect(actual).to include(%(<select name="book[store]" id="book-store">\n<option value="it">Italy</option>\n<option value="us">United States</option>\n<option value="" selected="selected">N&#x2F;A</option>\n</select>))
+      end
+
+      it "set as selected the option with nil value" do
+        actual = view.form_for(:book, action) do
+          select :store, option_values, options: { selected: nil }
+        end.to_s
+
+        expect(actual).to include(%(<select name="book[store]" id="book-store">\n<option value="it">Italy</option>\n<option value="us">United States</option>\n<option value="" selected="selected">N&#x2F;A</option>\n</select>))
+      end
+
+      it "set as selected the option with a value" do
+        actual = view.form_for(:book, action) do
+          select :store, option_values, options: { selected: 'it' }
+        end.to_s
+
+        expect(actual).to include(%(<select name="book[store]" id="book-store">\n<option value="it" selected="selected">Italy</option>\n<option value="us">United States</option>\n<option value="">N&#x2F;A</option>\n</select>))
+      end
+    end
   end
 
   describe '#datalist' do