g cases are and then add them.  Think about edge cases that could lurk in the extremes or cases that are uniquely distinguished from the provided tests, such as a completely empty string or a string composed of only non-letter characters.</p>

<p><strong>Add at least 1 new student test to expose the bug in the given implementation of <code class="language-c++ highlighter-rouge"><span class="n">lettersOnly</span></code>.</strong></p>

<p>Your goal in writing tests is to enumerate a comprehensive set of tests