Added an elementary unit test for CSP (#8340)

* Added an elementary test case for CSP

* removed input

* Rename test file to avoid running in CI

* Fix YAPF error

* Remove one line function handler

python/paddle/v2/fluid/tests/notest_csp.py

+#   Copyright (c) 2018 PaddlePaddle Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import unittest
+import paddle.v2.fluid as fluid
+
+
+class TestCSPFramework(unittest.TestCase):
+    def daisy_chain(self):
+        n = 10000
+        leftmost = fluid.make_channel(dtype=int)
+        right = leftmost
+        left = leftmost
+        with fluid.While(steps=n):
+            right = fluid.make_channel(dtype=int)
+            with fluid.go():
+                fluid.send(left, 1 + fluid.recv(right))
+            left = right
+
+        with fluid.go():
+            fluid.send(right, 1)
+        fluid.Print(fluid.recv(leftmost))
+
+
+if __name__ == '__main__':
+    unittest.main()