add support for concat and variadic tensor list (#40229)

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

@@ -722,13 +722,17 @@ class OpTest(unittest.TestCase):
 
         def assumption_assert_and_transform(args, argvs):
             """
-            currently only support "X" is [Tensor], don't support multi-tensor in "X"
+            transform by the following rules:
+                1. [Tensor] -> Tensor
+                2. [Tensor, Tensor, ...] -> list of Tensors
+
+            only support "X" is list of Tensor, currently don't support other structure like dict.
             """
             for inp in args:
-                assert isinstance(inp, list) and len(
-                    inp
-                ) == 1, "currently only support `X` is [Tensor], don't support multi-tensor in `X`"
-            args = [inp[0] for inp in args]
+                assert isinstance(
+                    inp, list
+                ), "currently only support `X` is [Tensor], don't support other structure."
+            args = [inp[0] if len(inp) == 1 else inp for inp in args]
             return args, argvs
 
         def cal_python_api(python_api, args, argvs, kernel_sig):
@@ -1239,15 +1243,16 @@ class OpTest(unittest.TestCase):
             dygraph_outs = self._calc_dygraph_output(
                 place, no_check_set=no_check_set)
 
+        if check_eager:
+            with _test_eager_guard():
+                eager_dygraph_outs = self._calc_dygraph_output(
+                    place, no_check_set=no_check_set)
+            # we only check end2end api when check_eager=True
             if hasattr(self, "python_api"):
                 api_outs = self._calc_python_api_output(place)
                 self._check_api_outs_by_dygraph_outs(api_outs, dygraph_outs,
                                                      place)
 
-        if check_eager:
-            with _test_eager_guard():
-                eager_dygraph_outs = self._calc_dygraph_output(
-                    place, no_check_set=no_check_set)
         outs, fetch_list = self._calc_output(place, no_check_set=no_check_set)
 
         for out_name, out_dup in Operator.get_op_outputs(self.op_type):

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

@@ -25,6 +25,7 @@ import paddle
 class TestConcatOp(OpTest):
     def setUp(self):
         self.op_type = "concat"
+        self.python_api = paddle.concat
         self.dtype = self.get_dtype()
         self.init_test_data()
         self.inputs = {'X': [('x0', self.x0), ('x1', self.x1), ('x2', self.x2)]}