Add tests for MetaInfo

MetaInfo.cc is one of the main component with untested code paths:

------------------------------------------------------------------------------
                           GCC Code Coverage Report
Directory: .
------------------------------------------------------------------------------
File                                       Lines    Exec  Cover   Missing
------------------------------------------------------------------------------
...
src/MetaInfo.cc                              268     161    60%   28-29,43,53,57,62,69,89,91,93-95,97,99-100,102-103,105-110,112-116,118-120,122-126,129-131,134,136-139,144-146,148-151,154-157,160,162-164,167-168,183-185,207,210,212,217-218,221-222,227-229,257,266,279-280,282-283,285-287,329-330,336-337,354,356-358,360-363,390-391,395-396,411,421,423,425,427,437,441-442
...
------------------------------------------------------------------------------
TOTAL                                       1857    1515    81%
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This represents almost 30% of the blind spots in our testing, so we should try and improve the situation.