Zero-dim support of histogram kernel, test=develop (#49884)

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

@@ -153,6 +153,14 @@ class TestHistogramOp(OpTest):
         self.check_output(check_eager=True)
 
 
+class TestHistogramOp_ZeroDim(TestHistogramOp):
+    def init_test_case(self):
+        self.in_shape = []
+        self.bins = 5
+        self.min = 1
+        self.max = 5
+
+
 if __name__ == "__main__":
     paddle.enable_static()
     unittest.main()

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

@@ -917,6 +917,11 @@ class TestSundryAPI(unittest.TestCase):
         self.assertEqual(out.grad.shape, [1])
         self.assertEqual(x.grad.shape, [])
 
+    def test_histogram(self):
+        x = paddle.rand([])
+        out = paddle.histogram(x, bins=5, min=1, max=5)
+        self.assertEqual(out.shape, [5])
+
     def test_scale(self):
         x = paddle.rand([])
         x.stop_gradient = False
@@ -1658,6 +1663,16 @@ class TestSundryAPIStatic(unittest.TestCase):
         self.assertEqual(res[1].shape, ())
         self.assertEqual(res[2].shape, (1,))
 
+    @prog_scope()
+    def test_histogram(self):
+        x = paddle.full([], 1, 'float32')
+        out = paddle.histogram(x, bins=5, min=1, max=5)
+
+        prog = paddle.static.default_main_program()
+        res = self.exe.run(prog, feed={}, fetch_list=[out])
+
+        self.assertEqual(res[0].shape, (5,))
+
     @prog_scope()
     def test_scale(self):
         x = paddle.rand([])