fix Uniform sample method (PaddlePaddle#37823)

python/paddle/distribution.py

@@ -305,7 +305,8 @@ def sample(self, shape, seed=0):
         else:
             output_shape = shape + batch_shape
             output = nn.uniform_random(
-                output_shape, seed=seed, dtype=self.dtype) * (tensor.zeros(
+                output_shape, dtype=self.dtype, min=0., max=1.,
+                seed=seed) * (tensor.zeros(
                     output_shape, dtype=self.dtype) + (self.high - self.low))
             output = elementwise_add(output, self.low, name=name)
             if self.all_arg_is_float:

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

@@ -336,6 +336,29 @@ def init_static_data(self, batch_size, dims):
                 name='values', shape=[dims], dtype='float32')
 
 
+class UniformTestSample(unittest.TestCase):
+    def setUp(self):
+        self.init_param()
+
+    def init_param(self):
+        self.low = 3.0
+        self.high = 4.0
+
+    def test_uniform_sample(self):
+        paddle.disable_static()
+        uniform = Uniform(low=self.low, high=self.high)
+        s = uniform.sample([100])
+        self.assertTrue((s >= self.low).all())
+        self.assertTrue((s < self.high).all())
+        paddle.enable_static()
+
+
+class UniformTestSample2(UniformTestSample):
+    def init_param(self):
+        self.low = -5.0
+        self.high = 2.0
+
+
 class NormalNumpy(DistributionNumpy):
     def __init__(self, loc, scale):
         self.loc = np.array(loc)