Introduce PrawnHtml::Instance class to preserve the context

Author: blocknotes

lib/prawn-html.rb

@@ -156,10 +156,7 @@ module PrawnHtml
   }.freeze
 
   def append_html(pdf, html)
-    pdf_wrapper = PdfWrapper.new(pdf)
-    renderer = DocumentRenderer.new(pdf_wrapper)
-    html_parser = PrawnHtml::HtmlParser.new(renderer)
-    html_parser.process(html)
+    PrawnHtml::Instance.new(pdf).append(html: html)
   end
 
   module_function :append_html
@@ -179,3 +176,4 @@ def append_html(pdf, html)
 require 'prawn_html/pdf_wrapper'
 require 'prawn_html/document_renderer'
 require 'prawn_html/html_parser'
+require 'prawn_html/instance'

lib/prawn_html/instance.rb

@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+module PrawnHtml
+  class Instance
+    attr_reader :html_parser, :pdf_wrapper, :renderer
+
+    def initialize(pdf)
+      @pdf_wrapper = PrawnHtml::PdfWrapper.new(pdf)
+      @renderer = PrawnHtml::DocumentRenderer.new(@pdf_wrapper)
+      @html_parser = PrawnHtml::HtmlParser.new(@renderer)
+    end
+
+    def append(html:)
+      html_parser.process(html)
+    end
+  end
+end

spec/units/prawn_html/instance_spec.rb

@@ -0,0 +1,39 @@
+# frozen_string_literal: true
+
+RSpec.describe PrawnHtml::Instance do
+  describe 'initialize' do
+    subject(:instance) { described_class.new(pdf) }
+
+    let(:pdf) { instance_double(Prawn::Document) }
+
+    before do
+      allow(PrawnHtml::PdfWrapper).to receive(:new)
+      allow(PrawnHtml::DocumentRenderer).to receive(:new)
+      allow(PrawnHtml::HtmlParser).to receive(:new)
+    end
+
+    it 'initializes the required entities', :aggregate_failures do
+      instance
+      expect(PrawnHtml::PdfWrapper).to have_received(:new)
+      expect(PrawnHtml::DocumentRenderer).to have_received(:new)
+      expect(PrawnHtml::HtmlParser).to have_received(:new)
+    end
+  end
+
+  describe '#append' do
+    subject(:append) { described_class.new(pdf).append(html: html) }
+
+    let(:html) { '<h1>Some HTML</h1>' }
+    let(:html_parser) { instance_double(PrawnHtml::HtmlParser, process: nil) }
+    let(:pdf) { instance_double(Prawn::Document) }
+
+    before do
+      allow(PrawnHtml::HtmlParser).to receive(:new).and_return(html_parser)
+    end
+
+    it 'sends a process message to the html parser' do
+      append
+      expect(html_parser).to have_received(:process).with(html)
+    end
+  end
+end