Enhance add_parameter check for dygraph layer (#26188)

* enhance add parameter check for layer

* add unittest for coverage

* remove uninit test case

* enrich unittest ccase

* trigger ci check

python/paddle/fluid/dygraph/layers.py

@@ -553,7 +553,10 @@ class Layer(core.Layer):
                 "The name of buffer should be a string, but received {}.".
                 format(type(name).__name__))
         elif '.' in name:
-            raise KeyError("The name of buffer can not contain \".\"")
+            raise KeyError(
+                "The name of buffer can not contain `.`, "
+                "because when you access the newly added buffer in the "
+                "form of `self.**.**`, it will cause AttributeError.")
         elif name == '':
             raise KeyError("The name of buffer can not be empty.")
         elif hasattr(self, name) and name not in self._buffers:
@@ -736,15 +739,33 @@ class Layer(core.Layer):
         Returns:
             Parameter: the parameter passed in.
         """
+        if '_parameters' not in self.__dict__:
+            raise RuntimeError(
+                "super(YourLayer, self).__init__() should be called firstly.")
+        elif not isinstance(name, six.string_types):
+            raise TypeError(
+                "The name of parameter should be a string, but received {}.".
+                format(type(name).__name__))
+        elif '.' in name:
+            raise KeyError(
+                "The name of parameter can not contain `.`, "
+                "because when you access the newly added parameter in the "
+                "form of `self.**.**`, it will cause AttributeError.")
+        elif name == '':
+            raise KeyError("The name of parameter can not be empty.")
+        elif hasattr(self, name) and name not in self._parameters:
+            raise KeyError("The parameter '{}' already exists.".format(name))
+        elif parameter is not None and not isinstance(parameter,
+                                                      framework.Parameter):
+            raise TypeError(
+                "The parameter to be added should be a Parameter, but received {}.".
+                format(type(parameter).__name__))
+        else:
             if parameter is None:
                 self._parameters[name] = None
-        elif not isinstance(parameter, framework.Parameter):
-            raise TypeError(
-                "parameter assignment requires Parameter or None, but got '{}'"
-                .format(type(parameter).__name__))
 
             if len(self._loaddict_holder) > 0:
-            assert parameter.name in self._loaddict_holder, "Parameter not found, Can't not find [ {} ] in stat_dict".format(
+                assert parameter.name in self._loaddict_holder, "Parameter not found, Can't not find [ {} ] in state_dict".format(
                     parameter.name)
 
                 parameter.set_value(self._loaddict_holder[parameter.name])

python/paddle/fluid/tests/unittests/test_base_layer.py

@@ -86,6 +86,31 @@ class TestBaseLayer(unittest.TestCase):
             ret = l()
             self.assertTrue(np.allclose(ret.numpy(), 0.8 * np.ones([2, 2])))
 
+    def test_add_parameter_with_error(self):
+        with fluid.dygraph.guard():
+            net = fluid.Layer()
+            param = net.create_parameter(shape=[1])
+
+            with self.assertRaises(TypeError):
+                net.add_parameter(10, param)
+
+            with self.assertRaises(KeyError):
+                net.add_parameter("param.name", param)
+
+            with self.assertRaises(KeyError):
+                net.add_parameter("", param)
+
+            with self.assertRaises(KeyError):
+                net.test_param = 10
+                net.add_parameter("test_param", param)
+
+            with self.assertRaises(TypeError):
+                net.add_parameter("no_param", 10)
+
+            load_param = net.create_parameter(shape=[1])
+            net._loaddict_holder[load_param.name] = load_param
+            net.add_parameter("load_param", load_param)
+
 
 class BufferLayer(fluid.Layer):
     def __init__(self):