function</span><span class="special">&lt;</span><span class="keyword">void</span><span class="special">()&gt;&amp;</span> <span class="identifier">teardown</span> <span class="special">=</span> <span class="special">{});</span>

<span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Fx</span><span class="special">&gt;</span>
  <span class="identifier">fixture</span><span class="special">&lt;</span><span class="identifier">Fx</spa