Convert relevant tests to testscenarios

Python's testscenarios support allows us to remove boiler plate code in some tests, and in other cases to report more unique errors. An example scenario test:

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from testscenarios import TestWithScenarios

scenario1 = ('basic', {'attribute': 'value'})
scenario2 = ('advanced', {'attribute': 'value2'})

class SampleWithScenarios(TestWithScenarios):

    scenarios = [scenario1, scenario2]

    def test_demo(self):
        self.assertIsInstance(self.attribute, str)

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This blueprint is to track changes which are converting tests to scenarios.