Stop updating method parameter takes arguments, and check this behaviour

The method writeable attribute should now be used to check if a method
takes parameter is writeable

malcolm/core/models.py

@@ -832,11 +832,6 @@ def __init__(self,
         self.elements = self.set_elements(elements if elements else {})
         self.required = self.set_required(required)
 
-    def set_writeable(self, writeable):
-        # type: (AWriteable) -> None
-        for v in self.elements.values():
-            v.set_writeable(writeable)
-
     def set_elements(self, elements):
         # type: (AElements) -> AElements
         deserialized = OrderedDict()
@@ -885,11 +880,6 @@ def __init__(self,
         self.defaults = self.set_defaults(defaults if defaults else {})
         super(MethodModel, self).__init__(description, tags, writeable, label)
 
-    def set_writeable(self, writeable):
-        # type: (AWriteable) -> AWriteable
-        self.takes.set_writeable(writeable)
-        return super(MethodModel, self).set_writeable(writeable)
-
     def set_takes(self, takes):
         # type: (ATakes) -> ATakes
         takes = deserialize_object(takes, MapMeta)

tests/test_modules/test_builtin/test_statefulcontroller.py

@@ -96,6 +96,8 @@ def test_init(self):
         self.start_process()
         assert list(self.b) == ['meta', 'health', 'state', 'disable', 'reset']
         assert self.b.state.value == "Ready"
+        assert self.b.disable.writeable is True
+        assert self.b.reset.writeable is False
 
     def test_reset_fails_from_ready(self):
         self.start_process()

tests/test_modules/test_scanning/test_runnablecontroller.py

@@ -173,9 +173,17 @@ def prepare_half_run(self, duration=0.01, exception=0):
             generator=compound, axesToMove=['x'], exceptionStep=exception)
 
     def test_configure_run(self):
+        assert self.b.configure.writeable is True
+        assert self.b.configure.takes.elements["generator"].writeable is True
+        assert self.b.validate.takes.elements["generator"].writeable is True
+        assert self.b.validate.returns.elements["generator"].writeable is False
         self.prepare_half_run()
         self.checkSteps(2, 0, 6)
         self.checkState(self.ss.ARMED)
+        assert self.b.configure.writeable is False
+        assert self.b.configure.takes.elements["generator"].writeable is True
+        assert self.b.validate.takes.elements["generator"].writeable is True
+        assert self.b.validate.returns.elements["generator"].writeable is False
 
         self.b.run()
         self.checkState(self.ss.ARMED)