add testing environment

app/views/icons/_api.html.erb

@@ -0,0 +1,7 @@
+<svg xmlns="http://www.w3.org/2000/svg" class="<%= local_assigns[:class] %>" width="44" height="44" viewBox="0 0 24 24" stroke-width="1.5" stroke="currentColor" fill="none" stroke-linecap="round" stroke-linejoin="round">
+  <path stroke="none" d="M0 0h24v24H0z" fill="none" />
+  <path d="M4 13h5" />
+  <path d="M12 16v-8h3a2 2 0 0 1 2 2v1a2 2 0 0 1 -2 2h-3" />
+  <path d="M20 8v8" />
+  <path d="M9 16v-5.5a2.5 2.5 0 0 0 -5 0v5.5" />
+</svg>