Add tests to check that invalid module specifications fail

features/examples/modules/invalid_both_defaults.py

@@ -0,0 +1,6 @@
+from wysdom import UserObject, UserProperty
+
+
+class Person(UserObject):
+    first_name: str = UserProperty(str)
+    last_name: str = UserProperty(str, default="", default_function=lambda x: x.first_name)

features/examples/modules/invalid_required_and_default.py

@@ -0,0 +1,6 @@
+from wysdom import UserObject, UserProperty
+
+
+class Person(UserObject):
+    first_name: str = UserProperty(str)
+    last_name: str = UserProperty(str, default="", optional=False)

features/invalid.feature

@@ -0,0 +1,17 @@
+Feature: Test that invalid module specifications fail
+
+  Scenario: Fail if both default and default_function are set
+
+    When we try to load the Python module invalid_both_defaults.py
+    Then a ValueError is raised with text:
+      """
+      Cannot use both default and default_function.
+      """
+
+  Scenario: Fail if both default is set and optional is set to False
+
+    When we try to load the Python module invalid_required_and_default.py
+    Then a ValueError is raised with text:
+      """
+      Cannot set optional to False if default or default_function are specified.
+      """

features/steps/steps.py

@@ -10,7 +10,7 @@
 
 
 @given("the Python module {module}.py")
-def step_impl(context, module):
+def load_python_module(context, module):
     spec = importlib.util.spec_from_file_location(
         module,
         os.path.join(
@@ -23,7 +23,30 @@ def step_impl(context, module):
     globals()[module] = loaded_module
 
 
-@step(u"the following string, {variable_name}")
+@when("we try to load the Python module {module}.py")
+def step_impl(context, module):
+    try:
+        load_python_module(context, module)
+        context.load_python_module_error = None
+    except Exception as e:
+        context.load_python_module_error = e
+
+
+@then("a {exception_type} is raised with text")
+def step_impl(context, exception_type):
+    if context.load_python_module_error is None:
+        raise Exception("No exception was raised.")
+    if exception_type != context.load_python_module_error.__class__.__name__:
+        raise Exception(
+            f"Expected exception type {exception_type}, got {type(context.load_python_module_error)}."
+        )
+    if context.text.strip() != str(context.load_python_module_error).strip():
+        raise Exception(
+            f"Expected error message '{context.text}', got '{context.load_python_module_error}'."
+        )
+
+
+@given(u"the following string, {variable_name}")
 def step_impl(context, variable_name):
     globals()[variable_name] = context.text