fix sqrt unittest. test=develop (#17440)

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

@@ -96,8 +96,8 @@ class TestLeakyReluDoubleGradCheck(unittest.TestCase):
 class TestSqrtDoubleGradCheck(unittest.TestCase):
     @prog_scope()
     def func(self, place):
-        shape = [7, 9]
-        eps = 0.005
+        shape = [3, 7]
+        eps = 0.0001
         dtype = np.float64
 
         x = layers.data('x', shape, False, dtype)
@@ -107,9 +107,9 @@ class TestSqrtDoubleGradCheck(unittest.TestCase):
         x_arr = np.random.uniform(0.1, 1, shape).astype(dtype)
 
         gradient_checker.double_grad_check(
-            [x], y, x_init=x_arr, place=place, eps=eps, rtol=1e-2, atol=1e-2)
+            [x], y, x_init=x_arr, place=place, eps=eps)
 
-    def no_test_grad(self):
+    def test_grad(self):
         places = [fluid.CPUPlace()]
         if core.is_compiled_with_cuda():
             places = [fluid.CUDAPlace(0)]