Add tests from Diffblue Deeptest

[paulkennethkent]

The test cases contained in this PR were automatically generated by Diffblue's Deeptest software.

Diffblue is an Oxford-based start-up that aims to automate traditional coding tasks to increase developer productivity. One of our missions is to provide useful tests to open source projects. In return, we would appreciate your feedback about our tests to help us further improve our tool.

These tests are part of a batch of 379 in total, providing an increase of 25.20% in line coverage. We would be happy to provide the remaining tests via a subsequent PR.

Results for various open source projects can be viewed at: http://diff.blue/demo

We welcome any feedback you have on these tests.