Fix #21894: Wrap constructor to Python to create initialized cuda::BufferPool object.

modules/python/test/test_cuda.py

@@ -45,5 +45,15 @@ class cuda_test(NewOpenCVTests):
         asyncstream = cv.cuda_Stream(1)  # cudaStreamNonBlocking
         self.assertTrue(asyncstream.cudaPtr() != 0)
 
+    def test_cuda_buffer_pool(self):
+        cv.cuda.setBufferPoolUsage(True)
+        cv.cuda.setBufferPoolConfig(cv.cuda.getDevice(), 1024 * 1024 * 64, 2)
+        stream_a = cv.cuda.Stream()
+        pool_a = cv.cuda.BufferPool(stream_a)
+        cuMat = pool_a.getBuffer(1024, 1024, cv.CV_8UC3)
+        cv.cuda.setBufferPoolUsage(False)
+        self.assertEqual(cuMat.size(), (1024, 1024))
+        self.assertEqual(cuMat.type(), cv.CV_8UC3)
+
 if __name__ == '__main__':
     NewOpenCVTests.bootstrap()