Add Extractor class

lib/headown.rb

@@ -1,4 +1,6 @@
 require 'headown/version'
+require 'open-uri'
+require 'commonmarker'
 
 module Headown
   class NotMarkdownError < StandardError
@@ -7,4 +9,32 @@ def initialize(file_path:)
       super(msg)
     end
   end
+
+  class Extractor
+    attr_reader :headers
+
+    def initialize(file_path)
+      raise Headown::NotMarkdownError.new(file_path: file_path) if File.extname(file_path) != '.md'
+
+      file_data = URI.open(file_path, &:read)
+      extract_headers(file_data)
+    end
+
+    private
+
+    def extract_headers(file_data)
+      @headers = header_nodes(file_data).map { |node| build_header(node) }
+    end
+
+    def header_nodes(data)
+      doc = CommonMarker.render_doc(data)
+      [].tap { |nodes| doc.walk { |node| nodes << node if node.type == :header } }
+    end
+
+    def build_header(node)
+      text = ''
+      node.each { |subnode| text = subnode.string_content if subnode.type == :text }
+      '#' * node.header_level + " #{text}"
+    end
+  end
 end

lib/headown/cli.rb

@@ -1,42 +1,17 @@
 require 'thor'
-require 'commonmarker'
-require 'open-uri'
 
 module Headown
   class CLI < Thor
     desc 'extract <path>', 'extract headers from file path'
 
     def extract(file_path)
-      raise Headown::NotMarkdownError.new(file_path: file_path) if File.extname(file_path) != '.md'
-
-      file_data = URI.open(file_path, &:read)
-      puts_headers(file_data)
+      extractor = Headown::Extractor.new(file_path)
+      puts extractor.headers
     rescue Headown::NotMarkdownError => e
       puts <<~MSG
       #{e.class}:
         #{e.message}
       MSG
     end
-
-    private
-
-    def header_nodes(data)
-      doc = CommonMarker.render_doc(data)
-      [].tap { |nodes| doc.walk { |node| nodes << node if node.type == :header } }
-    end
-
-    def build_header(node)
-      text = ''
-      node.each { |subnode| text = subnode.string_content if subnode.type == :text }
-      '#' * node.header_level + " #{text}"
-    end
-
-    def extract_headers(file_data)
-      header_nodes(file_data).map { |node| build_header(node) }
-    end
-
-    def puts_headers(file_data)
-      puts extract_headers(file_data)
-    end
   end
 end

spec/headown/cli_spec.rb

@@ -1,46 +1,6 @@
 RSpec.describe Headown::CLI do
   let(:headown) { described_class.new }
 
-  describe '#extract_headers' do
-    context 'when it finds a markdown file' do
-      it 'extracts headers' do
-        file_data = URI.open('spec/headown/sample.md', &:read)
-        expect(headown.send(:extract_headers, file_data)).to eq [
-             '# h1',
-             '## h2',
-             '### h3',
-             '#### h4',
-             '##### h5',
-             '###### h6'
-           ]
-      end
-    end
-
-    context 'when it finds a markdown file online' do
-      it 'extracts headers' do
-        file_data = URI.open('https://raw.githubusercontent.com/noriyotcp/headown/main/spec/headown/sample.md', &:read)
-        expect(headown.send(:extract_headers, file_data)).to eq [
-             '# h1',
-             '## h2',
-             '### h3',
-             '#### h4',
-             '##### h5',
-             '###### h6'
-           ]
-      end
-    end
-
-    # cf. https://spec.commonmark.org/0.29/#atx-headings
-    describe 'interrupting paragraphs' do
-      context 'when ATX headings are not separated from surrounding content by blank lines' do
-        it 'extracts headers' do
-          file_data = URI.open('spec/headown/sample2.md', &:read)
-          expect(headown.send(:extract_headers, file_data)).to eq ['# baz']
-        end
-      end
-    end
-  end
-
   describe '#extract' do
     context 'when it can NOT find a markdown file' do
       it 'can NOT extract headers' do

spec/headown_spec.rb

@@ -2,4 +2,28 @@
   it 'has a version number' do
     expect(Headown::VERSION).not_to be nil
   end
+
+  describe 'Headown::Extractor' do
+    subject { Headown::Extractor.new(file_path).headers }
+
+    describe '#headers' do
+      context 'when it finds a markdown file' do
+        let(:file_path) { 'spec/headown/sample.md' }
+        it { is_expected.to eq ['# h1', '## h2', '### h3', '#### h4', '##### h5', '###### h6'] }
+      end
+
+      context 'when it finds a markdown file online' do
+        let(:file_path) { 'https://raw.githubusercontent.com/noriyotcp/headown/main/spec/headown/sample.md' }
+        it { is_expected.to eq ['# h1', '## h2', '### h3', '#### h4', '##### h5', '###### h6'] }
+      end
+
+      # cf. https://spec.commonmark.org/0.29/#atx-headings
+      describe 'interrupting paragraphs' do
+        context 'when ATX headings are not separated from surrounding content by blank lines' do
+          let(:file_path) { 'spec/headown/sample2.md' }
+          it { is_expected.to eq ['# baz'] }
+        end
+      end
+    end
+  end
 end