Added methods to read excel properties from excel files

[breucode]

This PR enables the possibility to read excel properties (but only from XLSX files!).

Solves #151

[breucode]

Currently missing:

• Unit tests
• Readme update
• List of "core properties" (e.g. Properties, which excel has by default), which can be read
• Proper JavaDocs

[coveralls]

Coverage decreased (-1.4%) to 91.184% when pulling c331a89 on breucode:master into 81f0ab2 on ozlerhakan:master.

[ozlerhakan]

Hi @breucode , thanks for the changes! at first glance, we need to improve the code coverage a bit more :)

[breucode]

Hi @breucode , thanks for the changes! at first glance, we need to improve the code coverage a bit more :)

Hi @ozlerhakan :). As far as I can see, the only new untested code are private constructors and exception handling.

Should we add testing for exception handling to Poiji? If we do so, we could add a mocking framework for non-static calls. However, a lot of calls are static (e.g. OPCPackage.open(...)), so we either need to find a parameter, which triggers the exception. Alternatively, we need to go a functional way, where we can switch real method with a method, which throws the needed exception.

What would you say @ozlerhakan ?

[ozlerhakan]

I think we need to refrain ourselves to use/create static methods.

[breucode]

I think we need to refrain ourselves to use/create static methods.

I agree, but I don't see a way to replace calls like OPCPackage.open(...), which come from an external library.

[ozlerhakan]

I will look at it this weekend @breucode