Increasing the test coverage a bit

This PR increases a bit the global test coverage by providing a few more tests and test cases.
For me, test coverage go from:

Statements: 93.95% (606 / 645)
Branches: 91.63% (372 / 406)
Functions: 96.79% (181 / 187)
Lines: 93.95% (606 / 645) 

to:

Statements: 94.42% (609 / 645)
Branches: 91.87% (373 / 406)
Functions: 97.33% (182 / 187)
Lines: 94.42% (609 / 645)