JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.min.css">
<button>
  <div class="container">
    <i class="fa fa-file-pdf-o" aria-hidden="true"></i>
    <span>TestTestTestTestTestTestTestTestTestTestTestTestTestTestTestTestTestTestTestTestTestTestTestTestTestTestTestTestTestTestTestTestTestTestTestTestTestTestTestTestTestTestTestTestTestTestTestTestTestTestTestTestTestTestTestTestTestTestTestTestTestTestTestTest</span>
    <i class="fa fa-file-pdf-o" aria-hidden="true"></i>
  </div>
</button>

SCSS

body, button {
  max-width: 100px;
}

.container {
  width: 100%;
  display: -webkit-box;      /* OLD - iOS 6-, Safari 3.1-6 */
  display: -moz-box;         /* OLD - Firefox 19- (buggy but mostly works) */
  display: -ms-flexbox;      /* TWEENER - IE 10 */
  display: -webkit-flex;     /* NEW - Chrome */
  display: flex;             /* NEW, Spec - Opera 12.1, Firefox 20+ */
  
  span {
    flex: 1;
    -ms-flex: 1 0 auto;
    overflow: hidden;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
  }
}