add sub tag

Gemfile.lock

@@ -1,7 +1,7 @@
 PATH
   remote: .
   specs:
-    matestack-ui-core (0.7.0)
+    matestack-ui-core (0.7.1)
       cells-haml
       cells-rails
       haml

app/concepts/matestack/ui/core/sub/sub.haml

@@ -0,0 +1,5 @@
+%sub{@tag_attributes}
+  - if options[:text].nil? && block_given?
+    = yield
+  - else
+    = options[:text]

app/concepts/matestack/ui/core/sub/sub.rb

@@ -0,0 +1,5 @@
+module Matestack::Ui::Core::Sub
+  class Sub < Matestack::Ui::Core::Component::Static
+
+  end
+end

docs/components/sub.md

@@ -0,0 +1,47 @@
+# matestack core component: Sub
+
+Show [specs](../../spec/usage/components/sub_spec.rb)
+
+The HTML sub tag implemented in ruby.
+
+## Parameters
+
+This component can take 2 optional configuration params and either yield content or display what gets passed to the `text` configuration param.
+
+#### # id (optional)
+Expects a string with all ids the sub should have.
+
+#### # class (optional)
+Expects a string with all classes the sub should have.
+
+#### # text (optional)
+Expects a string with the text that should go into the `<sub>` tag.
+
+## Example 1: Yield a given block
+
+```ruby
+sub id: "foo", class: "bar" do
+  plain 'Hello World' # optional content
+end
+```
+
+returns
+
+```html
+<sub id="foo" class="bar">
+  Hello World
+</sub>
+```
+
+## Example 2: Render options[:text] param
+
+```ruby
+sub id: "foo", class: "bar", text: 'Hello World'
+```
+
+returns
+
+```html
+<sub id="foo" class="bar">
+  Hello World
+</sub>

spec/usage/components/sub_spec.rb

@@ -0,0 +1,66 @@
+require_relative "../../support/utils"
+include Utils
+
+describe 'Sub Component', type: :feature, js: true do
+
+  it 'Example 1 - yield, no options[:text]' do
+
+    class ExamplePage < Matestack::Ui::Page
+
+      def response
+        components {
+          # simple sub
+          sub do
+            plain 'I am simple'
+          end
+
+          # enhanced sub
+          sub id: 'my-id', class: 'my-class' do
+            plain 'I am enhanced'
+          end
+        }
+      end
+
+    end
+
+    visit '/example'
+
+    static_output = page.html
+
+    expected_static_output = <<~HTML
+    <sub>I am simple</sub>
+    <sub id="my-id" class="my-class">I am enhanced</sub>
+    HTML
+
+    expect(stripped(static_output)).to include(stripped(expected_static_output))
+  end
+
+  it 'Example 2 - render options[:text]' do
+
+    class ExamplePage < Matestack::Ui::Page
+
+      def response
+        components {
+          # simple sub
+          sub text: 'I am simple'
+
+          # enhanced sub
+          sub id: 'my-id', class: 'my-class',text: 'I am enhanced'
+        }
+      end
+
+    end
+
+    visit '/example'
+
+    static_output = page.html
+
+    expected_static_output = <<~HTML
+    <sub>I am simple</sub>
+    <sub id="my-id" class="my-class">I am enhanced</sub>
+    HTML
+
+    expect(stripped(static_output)).to include(stripped(expected_static_output))
+  end
+
+end