<!-- Pass, as aria IDREFs is not required here. Required things will be tested by other rules -->
<div aria-controls="missing">hi</div>
<!-- Incomplete, aria IDREFs is not required here, but this can be a real problem -->
<div aria-owns="missing">hi</div>
<div aria-describedby="missing">hi</div>
<div aria-labelledby="missing">hi</div>

<div role="tablist">
  <!-- Pass, no control expected -->
  <button aria-controls="missing" role="tab" aria-selected="false">hi</button>
  <!-- Pass, aria-selected default = false -->
  <button aria-controls="missing" role="tab">hi</button>
  <!-- Incomplete, because aria-controls is not required here -->
  <button aria-controls="missing" role="tab" aria-selected="true">hi</button>
  <!-- Invalid value defaults to "true" (weird that it doesn't default to the default) -->
  <button aria-controls="missing" role="tab" aria-selected="selected">hi</button>
</div>

<!-- Pass, no control expected -->
<input aria-controls="missing" role="combobox" aria-expanded="false" />
<!-- Pass. Axe will raise that aria-expanded is required -->
<input aria-controls="missing" role="combobox" />
<!-- Fail, control required -->
<input aria-controls="missing" role="combobox" aria-expanded="true" />

<!-- Pass, no control expected -->
<input aria-owns="missing" role="combobox" aria-expanded="false" />
<!-- Pass. Axe will raise that aria-expanded is required -->
<input aria-owns="missing" role="combobox" />
<!-- Fail, control required -->
<input aria-owns="missing" role="combobox" aria-expanded="true" />

<!--
  Pass:
  - aria-controls explicitly allows for elements that may not be present
  - ...and unlike the "selected tab" case, there is no role-based guidance that suggests it should most likely be otherwise
-->
<div aria-controls="missing">hi</div>

<!--
  Incomplete:
  - arguably, "ID reference" is required to be an ID of another element in the same document, so this should fail
  - ...but the history from issues #1524/#2621/#1151 convinces me that incomplete is ok.
  - Maybe we should double check AT impact and consider making these fail a separate best-practice rule
-->
<div aria-owns="missing">hi</div>
<div aria-describedby="missing">hi</div>
<div aria-labelledby="missing">hi</div>

<!-- Pass (I'm pretty sure you intended these to be implied already, just clarifying) -->
<div aria-controls="present">hi</div>
<div aria-owns="present">hi</div>
<div aria-describedby="present">hi</div>
<div aria-labelledby="present">hi</div>