Raise exception if positional arguments are used for Choice elements

See mvantellingen#439

Author: mvantellingen

CHANGES

@@ -3,8 +3,13 @@
  - Default values of optional elements are not set by default anymore (#423)
  - The call signature for Client.create_message() was changed. It now requires
    the service argument:
+
      ``Client.create_message(service, operation_name, *args, **kwargs)``
 
+ - Choice elements now only work with keyword arguments and raise an exception
+   if positional arguments are passed (#439)
+
+
 1.6.0 (2017-04-27)
 ------------------
  - Implement ValueObject.__json__ for json serialization (#258)

src/zeep/xsd/elements/indicators.py

@@ -106,6 +106,14 @@ def accept(self, values):
         return max(results)
 
     def parse_args(self, args, index=0):
+
+        # If the sequence contains an choice element then we can't convert
+        # the args to kwargs since Choice elements don't work with position
+        # arguments
+        for name, elm in self.elements_nested:
+            if isinstance(elm, Choice):
+                raise TypeError("Choice elements only work with keyword arguments")
+
         result = {}
         for name, element in self.elements:
             if index >= len(args):
@@ -283,6 +291,10 @@ def parse_xmlelements(self, xmlelements, schema, name=None, context=None):
 class Choice(OrderIndicator):
     """Permits one and only one of the elements contained in the group."""
 
+    def parse_args(self, args, index=0):
+        if args:
+            raise TypeError("Choice elements only work with keyword arguments")
+
     @property
     def is_optional(self):
         return True
@@ -702,4 +714,4 @@ def signature(self, schema=None, standalone=True):
             return '%s(%s)' % (
                 name, self.child.signature(schema, standalone=False))
         else:
-            return self.child.signature(schema, standalone=False)
+            return self.child.signature(schema, standalone=False)

tests/test_xsd_indicators_choice.py

@@ -95,6 +95,84 @@ def test_choice_element_second_elm():
     assert value.item_2 == 'foo'
     assert value.item_3 is None
 
+def test_choice_element_second_elm_positional():
+    node = etree.fromstring("""
+        <?xml version="1.0"?>
+        <xsd:schema
+                xmlns:xsd="http://www.w3.org/2001/XMLSchema"
+                xmlns:tns="http://tests.python-zeep.org/"
+                elementFormDefault="qualified"
+                targetNamespace="http://tests.python-zeep.org/">
+          <xsd:complexType name="type_1">
+            <xsd:sequence>
+              <xsd:element name="child_1" type="xsd:string"/>
+              <xsd:element name="child_2" type="xsd:string"/>
+            </xsd:sequence>
+          </xsd:complexType>
+          <xsd:complexType name="type_2">
+            <xsd:sequence>
+              <xsd:element name="child_1" type="xsd:string"/>
+              <xsd:element name="child_2" type="xsd:string"/>
+            </xsd:sequence>
+          </xsd:complexType>
+          <xsd:element name="container">
+            <xsd:complexType>
+              <xsd:choice>
+                <xsd:element name="item_1" type="tns:type_1" />
+                <xsd:element name="item_2" type="tns:type_2" />
+              </xsd:choice>
+            </xsd:complexType>
+          </xsd:element>
+          <xsd:element name="containerArray">
+            <xsd:complexType>
+              <xsd:sequence>
+                <xsd:choice>
+                    <xsd:element name="item_1" type="tns:type_1" />
+                    <xsd:element name="item_2" type="tns:type_2" />
+                </xsd:choice>
+              </xsd:sequence>
+            </xsd:complexType>
+          </xsd:element>
+        </xsd:schema>
+    """.strip())
+    schema = xsd.Schema(node)
+
+    child = schema.get_type('ns0:type_2')(child_1='ha', child_2='ho')
+
+    element = schema.get_element('ns0:container')
+    with pytest.raises(TypeError):
+        value = element(child)
+    value = element(item_2=child)
+
+    element = schema.get_element('ns0:containerArray')
+    with pytest.raises(TypeError):
+        value = element(child)
+    value = element(item_2=child)
+
+    element = schema.get_element('ns0:container')
+    value = element(item_2=child)
+    assert value.item_1 is None
+    assert value.item_2 == child
+
+    expected = """
+      <document>
+        <ns0:container xmlns:ns0="http://tests.python-zeep.org/">
+          <ns0:item_2>
+            <ns0:child_1>ha</ns0:child_1>
+            <ns0:child_2>ho</ns0:child_2>
+          </ns0:item_2>
+        </ns0:container>
+      </document>
+    """
+    node = etree.Element('document')
+    element.render(node, value)
+    assert_nodes_equal(expected, node)
+
+    value = element.parse(node[0], schema)
+    assert value.item_1 is None
+    assert value.item_2.child_1 == 'ha'
+    assert value.item_2.child_2 == 'ho'
+
 
 def test_choice_element_multiple():
     node = etree.fromstring("""