[Eager] Support test_label_smooth_functional switch to eager mode (#42366)

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

@@ -19,8 +19,6 @@ import paddle.fluid.dygraph as dg
 import paddle.nn.functional as F
 import paddle.fluid.initializer as I
 import unittest
-from paddle.fluid.framework import _enable_legacy_dygraph
-_enable_legacy_dygraph()
 
 
 class LabelSmoothTestCase(unittest.TestCase):

python/paddle/nn/functional/common.py

@@ -1633,14 +1633,14 @@ def label_smooth(label, prior_dist=None, epsilon=0.1, name=None):
             #[[[0.03333334 0.93333334 0.03333334]
             #  [0.93333334 0.03333334 0.93333334]]]
     """
+    if epsilon > 1. or epsilon < 0.:
+        raise ValueError("The value of epsilon must be between 0 and 1.")
+
     if in_dygraph_mode():
         return _C_ops.final_state_label_smooth(label, prior_dist,
                                                float(epsilon))
 
-    if epsilon > 1. or epsilon < 0.:
-        raise ValueError("The value of epsilon must be between 0 and 1.")
-
-    if paddle.in_dynamic_mode():
+    elif paddle.in_dynamic_mode():
         return _C_ops.label_smooth(label, prior_dist, 'epsilon', float(epsilon))
 
     check_variable_and_dtype(label, 'label', ['float32', 'float64'],