Unit test for hosting

[sachalevy]

We need to implement some unit tests for hosting requests posted by the user. Similar to #10, where mock HTTP streaming requests are required, we need to simulate a server response upon publishing a get request at a given producer channel. The tests should include verifying that the method handles ill-formed queries, fails gracefully, as well as can successfully process well-formed queries.

Note that here, in addition to mocking the HTTP streaming request, we'll need to mock the query posting request on result successful result retrieval from the pipeline.