Imo you always need to test error cases with web sites and apis specially. It&#x27;s just stupid that some API returns &quot;200: OK&quot;, {&quot;result&quot;: {&quot;error&quot;: &quot;result not found&quot;}}.<p>But I guess this is mainly about point of view. I used to be a developer, but now I&#x27;m employed full time as tester, so I have very different views on what needs to be tested than developers I know.