Check `help_page_url` by documentation link linter

Related issue: https://gitlab.com/gitlab-org/gitlab/-/issues/208354
Previou implementation MR:
https://gitlab.com/gitlab-org/gitlab/-/merge_requests/35351

**Problem**

The documentation link linter checks links defined by `help_page_path`
helper, however it ignores links from `help_page_url`.

**Solution**

Extend the pattern to match both `help_page_path` and `help_page_url`
helper methods

haml_lint/linter/documentation_links.rb

@@ -13,7 +13,7 @@ class DocumentationLinks < Linter
       DOCS_DIRECTORY = File.join(File.expand_path('../..', __dir__), 'doc')
 
       HELP_PATH_LINK_PATTERN = <<~PATTERN
-      `(send nil? :help_page_path $...)
+      `(send nil? {:help_page_url :help_page_path} $...)
       PATTERN
 
       MARKDOWN_HEADER = %r{\A\#{1,6}\s+(?<header>.+)\Z}.freeze

spec/haml_lint/linter/documentation_links_spec.rb

@@ -8,75 +8,85 @@
 RSpec.describe HamlLint::Linter::DocumentationLinks do
   include_context 'linter'
 
-  context 'when link_to points to the existing file path' do
-    let(:haml) { "= link_to 'Description', help_page_path('README.md')" }
+  shared_examples 'link validation rules' do |link_pattern|
+    context 'when link_to points to the existing file path' do
+      let(:haml) { "= link_to 'Description', #{link_pattern}('README.md')" }
 
-    it { is_expected.not_to report_lint }
-  end
+      it { is_expected.not_to report_lint }
+    end
 
-  context 'when link_to points to the existing file with valid anchor' do
-    let(:haml) { "= link_to 'Description', help_page_path('README.md', anchor: 'overview'), target: '_blank'" }
+    context 'when link_to points to the existing file with valid anchor' do
+      let(:haml) { "= link_to 'Description', #{link_pattern}('README.md', anchor: 'overview'), target: '_blank'" }
 
-    it { is_expected.not_to report_lint }
-  end
+      it { is_expected.not_to report_lint }
+    end
 
-  context 'when link_to points to the existing file path without .md extension' do
-    let(:haml) { "= link_to 'Description', help_page_path('README')" }
+    context 'when link_to points to the existing file path without .md extension' do
+      let(:haml) { "= link_to 'Description', #{link_pattern}('README')" }
 
-    it { is_expected.not_to report_lint }
-  end
+      it { is_expected.not_to report_lint }
+    end
 
-  context 'when anchor is not correct' do
-    let(:haml) { "= link_to 'Description', help_page_path('README.md', anchor: 'wrong')" }
+    context 'when anchor is not correct' do
+      let(:haml) { "= link_to 'Description', #{link_pattern}('README.md', anchor: 'wrong')" }
 
-    it { is_expected.to report_lint }
+      it { is_expected.to report_lint }
 
-    context 'when help_page_path has multiple options' do
-      let(:haml) { "= link_to 'Description', help_page_path('README.md', key: :value, anchor: 'wrong')" }
+      context "when #{link_pattern} has multiple options" do
+        let(:haml) { "= link_to 'Description', #{link_pattern}('README.md', key: :value, anchor: 'wrong')" }
+
+        it { is_expected.to report_lint }
+      end
+    end
+
+    context 'when file path is wrong' do
+      let(:haml) { "= link_to 'Description', #{link_pattern}('wrong.md'), target: '_blank'" }
 
       it { is_expected.to report_lint }
     end
-  end
 
-  context 'when file path is wrong' do
-    let(:haml) { "= link_to 'Description', help_page_path('wrong.md'), target: '_blank'" }
+    context 'when link with wrong file path is assigned to a variable' do
+      let(:haml) { "- my_link = link_to 'Description', #{link_pattern}('wrong.md')" }
 
-    it { is_expected.to report_lint }
-  end
+      it { is_expected.to report_lint }
+    end
 
-  context 'when link with wrong file path is assigned to a variable' do
-    let(:haml) { "- my_link = link_to 'Description', help_page_path('wrong.md')" }
+    context 'when it is a broken code' do
+      let(:haml) { "= I am broken! ]]]]" }
 
-    it { is_expected.to report_lint }
-  end
+      it { is_expected.not_to report_lint }
+    end
 
-  context 'when it is a broken code' do
-    let(:haml) { "= I am broken! ]]]]" }
+    context 'when anchor belongs to a different element' do
+      let(:haml) { "= link_to 'Description', #{link_pattern}('README.md'), target: (anchor: 'blank')" }
 
-    it { is_expected.not_to report_lint }
-  end
+      it { is_expected.not_to report_lint }
+    end
 
-  context 'when anchor belongs to a different element' do
-    let(:haml) { "= link_to 'Description', help_page_path('README.md'), target: (anchor: 'blank')" }
+    context "when a simple #{link_pattern}" do
+      let(:haml) { "- url = #{link_pattern}('wrong.md')" }
 
-    it { is_expected.not_to report_lint }
-  end
+      it { is_expected.to report_lint }
+    end
 
-  context 'when a simple help_page_path' do
-    let(:haml) { "- url = help_page_path('wrong.md')" }
+    context 'when link is not a string' do
+      let(:haml) { "- url = #{link_pattern}(help_url)" }
 
-    it { is_expected.to report_lint }
-  end
+      it { is_expected.not_to report_lint }
+    end
 
-  context 'when link is not a string' do
-    let(:haml) { "- url = help_page_path(help_url)" }
+    context 'when link is a part of the tag' do
+      let(:haml) { ".data-form{ data: { url: #{link_pattern}('wrong.md') } }" }
 
-    it { is_expected.not_to report_lint }
+      it { is_expected.to report_lint }
+    end
   end
 
-  context 'when link is a part of the tag' do
-    let(:haml) { ".data-form{ data: { url: help_page_path('wrong.md') } }" }
+  context 'help_page_path' do
+    it_behaves_like 'link validation rules', 'help_page_path'
+  end
 
-    it { is_expected.to report_lint }
+  context 'help_page_url' do
+    it_behaves_like 'link validation rules', 'help_page_url'
   end
 end