Make sure that servicex can be called by default

We can now call with a default ctor and not worry about configuration settings.

Workign on #111

Author: gordonwatts

servicex/servicex.py

@@ -95,10 +95,6 @@ def __init__(self,
                              status_callback_factory,
                              )
 
-        # Make sure the arguments are reasonable
-        if backend_type is None and servicex_adaptor is None:
-            raise ServiceXException('Specify backend_type or servicex_adaptor')
-
         # Get the local settings
         config = config_adaptor if config_adaptor is not None \
             else ServiceXConfigAdaptor()
@@ -110,7 +106,6 @@ def __init__(self,
 
         if not servicex_adaptor:
             # Given servicex adaptor is none, this should be ok. Fixes type checkers
-            assert backend_type is not None
             end_point, email, password = config.get_servicex_adaptor_config(backend_type)
             servicex_adaptor = ServiceXAdaptor(end_point, email, password)
         self._servicex_adaptor = servicex_adaptor

tests/test_servicex.py

@@ -41,11 +41,19 @@ def test_default_ctor(mocker):
     config.get_default_returned_datatype.assert_called_with('uproot-ftw')
 
 
-def test_default_ctor_no_type():
-    with pytest.raises(ServiceXException) as e:
-        fe.ServiceXDataset('localds://dude')
+def test_default_ctor_no_type(mocker):
+    '''Test the default ctor. This requires that a .servicex file be present to work,
+    so we are going to dummy it out.
+    '''
+    config = mocker.MagicMock(spec=ServiceXConfigAdaptor)
+    config.settings = Configuration('servicex', 'servicex')
+    config.get_servicex_adaptor_config.return_value = ('http://no-way.dude', 'j@yaol.com',
+                                                       'no_spoon_there_is')
+
+    fe.ServiceXDataset('localds://dude', config_adaptor=config)
 
-    assert "type" in str(e.value)
+    config.get_servicex_adaptor_config.assert_called_with(None)
+    config.get_default_returned_datatype.assert_called_with(None)
 
 
 @pytest.mark.asyncio