fix div 0 error of NoamDecay (PaddlePaddle#49953)

* fix div 0 error of NoamDecay

* add unittest

* Update lr.py

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

@@ -0,0 +1,34 @@
+#  Copyright (c) 2023 PaddlePaddle Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import unittest
+
+import paddle
+
+
+class TestSparseEmbeddingAPIError(unittest.TestCase):
+    def test_errors(self):
+        with paddle.fluid.dygraph.guard():
+            # The size of input in sparse_embedding should not be 0.
+            def test_0_d_model():
+                schedular = paddle.optimizer.lr.NoamDecay(
+                    d_model=0, warmup_steps=0
+                )
+
+            self.assertRaises(ValueError, test_0_d_model)
+
+
+if __name__ == '__main__':
+    paddle.enable_static()
+    unittest.main()

python/paddle/optimizer/lr.py

@@ -296,6 +296,9 @@ def __init__(
         last_epoch=-1,
         verbose=False,
     ):
+        if d_model <= 0:
+            raise ValueError("d_model should be grater than 0")
+
         self.d_model = d_model
         self.warmup_steps = warmup_steps
         super().__init__(learning_rate, last_epoch, verbose)