<p><code>String "enormous", "large" "medium" or "small",
default is "medium"; optional</code></p>

<p>How "heavy" the test is.</p>

<p>A classification of the test's "heaviness": how much time/resources
it needs to run.</p>

<p>Unittests are considered "small", integration tests "medium", and
end-to-end tests "large" or "enormous". Bazel uses the size only
to determine a default timeout.</p>
