API 0.1 unit testing

[iranroman]

we need unit tests with full coverage of this API version, as it will be the first functional one, and we currently have no tests. Parameterized testing with pytest is recommended.

[iranroman]

We will continue making progress on this, but as of #52 we are still in need to work on unit testing. This is also related to #44

[iranroman]

Some new end-to-end tests are added in #60 . More work remains to be done.