basic_erb_templating.rb

require 'erb'

expected = %{
<ul>
  <li>1</li>
  <li>2</li>
  <li>3</li>
</ul>
}

template_unindented = %{
<ul>
<% list = [1,2,3] %>
<% for item in list %>
<% if item %>
<li><%= item %></li>
<% end %>
<% end %>
</ul>
 } # space is needed for correct formating

template_indented = %{
<ul>
  <% list = [1,2,3] %>
  <% for item in list %>
  <% if item %>
  <li><%= item %></li>
  <% end %>
  <% end %>
</ul>
}

template_indented_with_surrounded_dash = %{
<ul>
  <%- list = [1,2,3] -%>
  <%- for item in list -%>
  <%- if item -%>
  <li><%= item %></li>
  <%- end -%>
  <%- end -%>
</ul>
}

template_indented_with_ending_dash = %{
<ul>
  <% list = [1,2,3] -%>
  <% for item in list -%>
  <% if item -%>
  <li><%= item %></li>
  <% end -%>
  <% end -%>
</ul>
}

templates = [
  {
    name: 'template_unindented',
    trim_mode: '<>',
    content: template_unindented
  },
  {
    name: 'template_indented',
    trim_mode: '<>',
    content: template_indented
  },
  {
    name: 'template_indented',
    trim_mode: '%>',
    content: template_indented
  },
  {
    name: 'template_indented',
    trim_mode: '-',
    content: template_indented
  },
  {
    name: 'template_indented_with_surrounded_dash',
    trim_mode: '-',
    content: template_indented_with_surrounded_dash
  },
  {
    name: 'template_indented_with_ending_dash',
    trim_mode: '-',
    content: template_indented_with_ending_dash
  }
]

templates.each do |template|
  puts "🎲  With trim_mode: #{template[:trim_mode]}, for #{template[:name]}\n\n"
  pp ERB.new(template[:content], trim_mode: template[:trim_mode]).result
  puts
end

puts "🎲  Expected\n\n"

pp expected

🎲  With trim_mode: <>, for template_unindented

"\n" +
"<ul>\n" +
"<li>1</li>\n" +
"<li>2</li>\n" +
"<li>3</li>\n" +
"</ul>\n" +
" "

🎲  With trim_mode: <>, for template_indented

"\n" +
"<ul>\n" +
"  \n" +
"  \n" +
"  \n" +
"  <li>1</li>\n" +
"  \n" +
"  \n" +
"  \n" +
"  <li>2</li>\n" +
"  \n" +
"  \n" +
"  \n" +
"  <li>3</li>\n" +
"  \n" +
"  \n" +
"</ul>\n"

🎲  With trim_mode: %>, for template_indented

"\n" +
"<ul>\n" +
"        <li>1</li>\n" +
"        <li>2</li>\n" +
"        <li>3</li>\n" +
"    </ul>\n"

🎲  With trim_mode: -, for template_indented

"\n" +
"<ul>\n" +
"  \n" +
"  \n" +
"  \n" +
"  <li>1</li>\n" +
"  \n" +
"  \n" +
"  \n" +
"  <li>2</li>\n" +
"  \n" +
"  \n" +
"  \n" +
"  <li>3</li>\n" +
"  \n" +
"  \n" +
"</ul>\n"

🎲  With trim_mode: -, for template_indented_with_surrounded_dash

"\n" +
"<ul>\n" +
"  <li>1</li>\n" +
"  <li>2</li>\n" +
"  <li>3</li>\n" +
"</ul>\n"

🎲  With trim_mode: -, for template_indented_with_ending_dash

"\n" +
"<ul>\n" +
"        <li>1</li>\n" +
"        <li>2</li>\n" +
"        <li>3</li>\n" +
"    </ul>\n"

🎲  Expected

"\n" +
"<ul>\n" +
"  <li>1</li>\n" +
"  <li>2</li>\n" +
"  <li>3</li>\n" +
"</ul>\n"