#12429 uses pytest fixture to create resource group, eventhub namespace and eventhubs for the event hubs tests.
It doesn't work with resource preparer, which requires all test methods to be in a subclass of AzureMgmtTestCase, a descendent of unittest.TestCase.

There are two options in the future:

1. Update event hub tests to be in a subclass of AzureMgmtTestCase.
2. Make resource preparer to be compatible with pytest fixtures.