Permit to remove a specific rule/value from the context styles

Author: blocknotes

lib/prawn_html/attributes.rb

@@ -76,6 +76,18 @@ def merge_text_styles!(text_styles, options: {})
       process_styles(hash_styles, options: options) unless hash_styles.empty?
     end
 
+    # Remove an attribute value from the context styles
+    #
+    # @param context_styles [Hash] hash of the context styles that will be updated
+    # @param rule [Hash] rule from the STYLES_LIST to lookup in the context style for value removal
+    def remove_value(context_styles, rule)
+      if rule[:set] == :append_styles
+        context_styles[rule[:key]] -= rule[:values] if context_styles[:styles]
+      else
+        context_styles.delete(rule[:key])
+      end
+    end
+
     # Update context styles applying the initial rules (if set)
     #
     # @param context_styles [Hash] hash of the context styles that will be updated

spec/units/prawn_html/attributes_spec.rb

@@ -71,6 +71,28 @@
     end
   end
 
+  describe '#remove_value' do
+    subject(:remove_value) { attributes.remove_value(context_styles, rule) }
+
+    let(:context_styles) { { size: 9.6, styles: %i[bold italic] } }
+
+    context 'with a missing rule' do
+      let(:rule) { { key: :color, set: :convert_color } }
+
+      it "doesn't change the context styles" do
+        expect { remove_value }.not_to change(context_styles, :values)
+      end
+    end
+
+    context 'with an applied rule' do
+      let(:rule) { { key: :styles, set: :append_styles, values: %i[bold] } }
+
+      it "changes the context styles" do
+        expect { remove_value }.to change(context_styles, :values).from([9.6, %i[bold italic]]).to([9.6, %i[italic]])
+      end
+    end
+  end
+
   describe '.merge_attr!' do
     context 'with an empty key' do
       let(:key) { nil }