If the length is not 0, then compare the actual string, eg:

```
EXPECT_EQ("whatever it be", res.responseVector.get(0)->errorCode.reasonPhrase);
```

However, I think this a consequence of using "Ununitialized" as reasonPhase (see previous comment at https://github.com/telefonicaid/fiware-orion/pull/211#discussion_r9457510)